Venkata Narasimham Nori- Unsteady Flow in a Mixed-Compression Inlet at Mach 3.5

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UNSTEADY FLOW IN A MIXED-COMPRESSION INLETAT MACH 3.5

By

VENKATA NARASIMHAM NORI

A THESIS PRESENTED TO THE GRADUATE SCHOOLOF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT

OF THE REQUIREMENTS FOR THE DEGREE OF

MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2003



Copyright 2003

by

Venkata Narasimham Nori



To the One and only One.



ACKNOWLEDGMENTS

I would like to sincerely thank Dr. Corin Segal for providing me this opportunity

and guiding me carefully on this path. Without his advice and incredible patience, this

work would not have been possible. I would like to thank Dr. David Mikolaitis and Dr.

Bruce Carroll for their advice and valuable suggestions to improve the quality of work.

This work was supported both by the Office of Naval Research with Dr. Gabriel

Roy as the technical monitor, and NASA Glenn Research Center under the supervision of

Rene Fernandez.

I would like to thank Jonas for helping me so much in virtually all stages of this

work. It was a great pleasure learning from him that with patience, perseverance and

enthusiastic attitude any problem is surmountable. His wit and sense of humor restored

tranquility amidst a raging storm and maintained poise in the lab.

Then there is Nelson who was adept in solving practical problems of any kind.

Without him, the sting support would have bent and the model would have had hundreds

of test flights in the wind tunnel! He modified Nike’s punch line to “Don’t think! Just Do

It” which made us rapidly converge to a working experimental setup. I am happy to have

worked with such a cheerful and pragmatic guy.

Abhilash demonstrating the “shocking truth” whenever he ran a test, Danny

fiddling with his Scram “jet set” facility and Jayanth figuring out ways to detect “leaks”

using mass spectrometer also contributed in maintaining the tempo of the group.

iv



I thank Sudarshan for sharing his experiences and also suggesting ways to

troubleshoot some problems. I sincerely thank Ron Brown for his timely suggestions and

neat fixes in times of calamities, the climax being a clever temporary solution for the

Wind Tunnel. He was always eager to help and always enquired about the progress of the

project. I thank Ken Reed for his brilliant machinist skills and professionalism without

which the models would not be so good.

My heartfelt thanks go to Srikanth (SV) who has taken the pains to wake me up

every day, early in the morning making a long distance call. With encouraging words and

thoughts of strength, he recharged my batteries.

I am grateful to my roommates Gopal, Saurav and Archit who were very

understanding and supportive. Laudable are their efforts to adjust and accommodate a

guy like me. Thanks to their enthusiasm, I had sumptuous food at the end of the day.

They always offered a lending hand whenever I was troubled and confused.

I thank Priya kutti and Jose for their encouragement and their concern about the

progress of the project.

A million thanks go to Charan, Anand, Sasidhar, Sai Shankar, Naveen, Chakri,

Sriram, Sai Krishna, Anurag, Rax, Hari, Ryan, Quentin, Weizhong, Amith, Sujith, Balaji,

Bolt, Ahmed, Sampath and many more. Last but not least, cheers go to the people of

gatorland who by their friendly smiles kept me in “high spirits,” making my stay in

Gainesville a very enjoyable and memorable experience.

Really speaking, these words are still insufficient to convey my heartfelt wishes to

all the people mentioned above.

v



TABLE OF CONTENTS

page

ACKNOWLEDGMENTS ................................................................................................. iv

LIST OF TABLES........................................................................................................... viii

LIST OF FIGURES ........................................................................................................... ix

LIST OF OBJECTS ........................................................................................................... xi

ABSTRACT...................................................................................................................... xii

CHAPTERS

1 INTRODUCTION ...........................................................................................................1

1.1 Review of Relevant Literature on Inlet Flow Oscillations ....................................... 21.2 Motivation for Current Study.................................................................................... 8

1.2.1 A New Engine Concept-Pulse Detonation Engine.......................................... 8

1.2.2 Intent and Scope of Work ............................................................................. 11

2 EXPERIMENTAL SETUP............................................................................................12

2.1 Introduction............................................................................................................. 12

2.2 Basic Inlet Geometry .............................................................................................. 12

2.3 Backpressure Excitation Mechanism...................................................................... 172.4 Description of the Wind Tunnel ............................................................................. 22

2.5 Instrumentation ....................................................................................................... 24

2.6 Schlieren Setup ....................................................................................................... 26

2.7 Oil Flow Visualization............................................................................................ 26

3 RESULTS ......................................................................................................................28

3.1 Introduction............................................................................................................. 283.2 Flow Field Inside the Inlet ...................................................................................... 28

3.2.1 The Supersonic Inlet ..................................................................................... 28

3.2.2 The Supercritical Inlet................................................................................... 293.3 Preliminary Calibration........................................................................................... 30

3.4 Static and Stagnation Pressure Measurements........................................................ 31

3.4.1 Effects of Injection Configuration ................................................................ 323.4.2 Effects of Mass Injection .............................................................................. 41

vi



3.4.3 Frequency Effects.......................................................................................... 50

3.4.4 Exit Stagnation Pressure ............................................................................... 513.5 Implications of Design and Size ............................................................................. 54

4 SUMMARY...................................................................................................................55

APPENDIX

A DATA ACQUISITION PROGRAM............................................................................57

B MATLAB PROGRAM FOR DATA REDUCTION ....................................................93

C INLET DRAWINGS...................................................................................................114

D SCHLIEREN MOVIES ..............................................................................................120

LIST OF REFERENCES.................................................................................................130

BIOGRAPHICAL SKETCH ...........................................................................................132

vii



LIST OF TABLES

Table page

2-1. Coordinates of points that make the ramp profile ......................................................13

2.2 Location of wall static pressure taps............................................................................16

C-1. Coordinates of points relative to the leading edge of the ramp that make the ramp

profile...................................................................................................................116

D-1. List of schlieren movies...........................................................................................121

viii



LIST OF FIGURES

Figure page

1-1. PDE cycle schematic showing the events typical of operation of a single detonationtube.........................................................................................................................10

2-1. Views of the inlet showing the main components and the provision for backpressureexcitation................................................................................................................12

2-2. Shock structure as calculated from simple oblique shock relations ...........................14

2-3. Inlet schematic showing the location of static pressure taps and bleed plenums.......14

2-4. Oil flow test on the ramp. ...........................................................................................15

2-5. Top view of the ramp showing the bleed holes and the static tap locations...............16

2-6. CAD drawings ............................................................................................................17

2-7. Frontal and rear view of the exit injection block........................................................18

2-8. Illustration of the exit injection block with the port designations and the injection

configurations below..............................................................................................19

2-9. Layout of the key components of the air injection mechanism..................................21

2-10. Schematic of the pulse generator circuit...................................................................23

2-11. Schematic of tunnel valve control.26

.........................................................................25

2-12. Schematic of the schlieren system.26

........................................................................27

3-1. Comparison of mean static pressures in the inlet for the blocked and the unblockedconfiguration..........................................................................................................29

3-2. Schlieren images.........................................................................................................30

3-3. Comparison between the ramp and the cowl mean normalized static pressures........31

3-4. Views of the exit injection block with the stagnation pressure rake embedded in itwith the probe designations. ..................................................................................32

ix



3-5. Plots for comparing the excited and the unexcited inlet, for Minj=20% and

Frequency = 5 Hz case...........................................................................................35

3-6. Schlieren images for the 5 Hz and 20% mass injection36

3-7. Comparing the effects of injection configuration on the inlet flowfield. ...................38

3-8. Comparing the effects of mass injection for two different injection mass flows-20%

and 40% of capture. ...............................................................................................43

3-9. Schlieren images for comparing the 20% and 40% mass injection cases. .................46

3-10. Static pressure –time trace for the AS-2 coupling, 20% mass injection and 5 Hz

case.........................................................................................................................47

3-11. Static pressure –time trace for the AS-2 coupling, 40% mass injection and 5 Hz

case.........................................................................................................................49

3-12. Comparing the effects of two different excitation frequencies-5 Hz & 10 Hz.........52

A-1. Flowchart showing the data acquisition and experimental automation.26

.................58

C-1. The cowl...................................................................................................................114

C-2. The inlet ramp. .........................................................................................................115

C-3. The sideplates...........................................................................................................117

C-4. The sting...................................................................................................................117

C-5. The exit injection block. ..........................................................................................118

C-6. The inlet assembly. ..................................................................................................119

x



LIST OF OBJECTS

Object page

D-1.S-2 Coupling, Minj=20.7%, F=10 Hz. .....................................................................122

D-2. AS-2 Coupling, Minj=20.7%, F=10 Hz. .................................................................122

D-3. 90 Phase Coupling, Minj=20%, F=10Hz.................................................................123

D-4. AS-2 Coupling, Minj=18.5%, F=5 Hz. ...................................................................123

D-5. S-2 Coupling, Minj=18.5%, F=5 Hz. ......................................................................124

D-6. S-1 Coupling, Minj=19.5%, F=5 Hz. ......................................................................124

D-7. AS-3 Coupling, Minj=19.5%, F=5 Hz. ...................................................................125

D-8. 90 Phase Coupling, Minj=23%, F=5 Hz..................................................................125

D-9. S-1 Coupling, Minj=39%, F=5 Hz. .........................................................................126

D-10. AS-3 Coupling, Minj=39%, F=5 Hz. ....................................................................126

D-11. S-2 Coupling, Minj=39%, F=5 Hz. .......................................................................127

D-12. AS-2 Coupling, Minj=39%, F=5 Hz. ....................................................................127

D-13. 90 Phase Coupling, Minj=39%, F=5 Hz................................................................128

D-14. Zoomed view of terminal shock for the S-2 Coupling, Minj=23%, F=5 Hz case.128

D-15. Zoomed view at capture for the 90 Phase Coupling, Minj=47%, F=5 Hz case. ...129

xi



Abstract of Thesis Presented to the Graduate School

of the University of Florida in Partial Fulfillment of the

Requirements for the Degree of Master of Science

UNSTEADY FLOW IN A MIXED-COMPRESSION INLETAT MACH 3.5

By

Venkata Narasimham Nori

May 2003

Chair: Corin Segal

Major Department: Mechanical and Aerospace Engineering

A study of flow field in a two dimensional, mixed compression, supersonic inlet

under periodically varying external excitation of the backpressure was conducted at a

freestream Mach number of 3.5. The aim of the study was to simulate the effects of

combustion tube detonations due to a pulse detonation engine on the inlet. Four air

disturbance ports located at the corners of the exit cross-section simulated the pressure

perturbations. The frequency, coupling of the disturbance ports and the airflow rates

through the ports were varied. A terminal normal shock in the diffuser was observed in

the unexcited inlet whose oscillations during the backpressure excitation caused the

associated pressure oscillations. The mean levels of static pressure downstream of the

throat increased in all the test conditions due to mass injection. The schlieren and oil flow

visualization images confirmed the existence of a large separation bubble on the second

wedge of the ramp, which caused a complex shock and wave system. Large injection

mass flows result in inlet flow oscillations measured throughout the entire inlet, yet did

xii



not cause inlet unstart. Except for the 90 Phase coupling, there was no effect of injection

mass flows on the mean levels of static pressure but higher pressure oscillations were

observed for the larger injection mass flows. Pressure data and schlieren images showed

that the lower frequencies of excitation result in greater pressure oscillations. The 90

Phase coupling produced the highest mean levels of static pressure but generated the

lowest levels of pressure oscillations when compared to other injection configurations.

The mean stagnation pressure recovery at the exit was about 0.32 and the static pressure

rise in the inlet was about 15.

xiii



CHAPTER 1INTRODUCTION

The function of the inlet is to provide appropriate mass flow and velocity to the

engine with high total pressure recovery, flow uniformity and flow stability, all of which

are important to the overall engine efficiency. The leading edge shock system, the

terminal shock boundary layer interaction, the decelerating subsonic flow and the

associated rapidly growing boundary layers combine to form typical inlet flows. Stability

of flow is one of the major considerations in designing supersonic inlets. The interaction

between the inlet and the engine flowfield may cause instability for the entire system.

Analysis of supersonic inlet flows are complicated by the presence of mixed subsonic and

supersonic flows, shock boundary layer interactions that may or may not cause

separation. The disturbances/transients in the inlet or the engine can be decomposed in to

three components: entropy generation, vorticity and acoustic modes. The response

generated may contain all the three disturbance types. However, the entropy and vorticity

disturbances are always convected downstream and only the acoustic response has an

upstream moving part. It is this response that actually affects the inlet flow.1

The pressure

oscillations generated by unsteady combustion may induce shock wave oscillations in the

inlet duct. These oscillations can grow, causing large distortions in the shock structure

leading to dramatic degradation of the engine performance. This work examines the

effect of pressure oscillations arising from the combustion tube detonations due to a pulse

detonation engine on the flowfield, in a two dimensional, mixed compression, supersonic

inlet.

1



2

1.1 Review of Relevant Literature on Inlet Flow Oscillations

Over the past few decades, theoretical and experimental research on both self

excited and externally excited flow oscillations in air intakes have been conducted to

identify the flow patterns and parameters that induce instabilities that decrease engine

performance. Most of the research on the inlet-engine interactions focused on instabilities

arising from the combustion chambers of Ramjet engines and confined to transonic

diffuser flows. This chapter reviews the study on pressure oscillations in air intakes by a

selected few researchers, followed by the motivation for this study.

Mullagiri et al.2, 3

have experimentally investigated the effects of a PDE on the air

induction system on two-dimensional and axisymmetric inlets at freestream Mach

numbers of 2.5 and 2.1. The pressure perturbations at the diffuser exit have been

simulated by mechanically varying the exit area resulting in a sinusoidal excitation of the

backpressure, both spatially and temporally. The excitation was varied from 15 to 50 Hz

and the amplitude was varied by increasing the blockage at the exit plane. It was

observed that the pressure oscillations were confined to the downstream of the throat in

both the cases. Also, a decrease in the amplitude of the pressure perturbations with

increase of excitation frequency was observed. Moreover, increase in the amplitude of

excitation caused an increase in the mean pressure field in the diffuser.

Chen et al., Bogar et al., and Sajben et al.4–8

conducted a series of experimental

investigations into inlet diffuser flows with pressure oscillations, to better understand the

unsteady flow behavior in a Ramjet engine. Various unsteady flow phenomena, such as

shock induced separated flows and shock/acoustic wave interactions under self excited

and forced oscillations were treated in detail. From the experiments of supercritical

transonic diffuser flows displaying self-excited fluctuations, it was found that the bulk of



3

the fluctuation energy was contained in the frequency range of shock oscillations, which

were below 300 Hz. The diffuser was run at a supercritical condition at Mach numbers

ranging form 1.1 to 1.5. Depending on the Mach number, two different flow patterns

were identified. At lower Mach numbers, a flow separation was caused by adverse

pressure gradients (weak shock case) whereas at higher Mach numbers shock induced

separation was observed (strong shock case). For the weak shock case the peak

oscillation frequency decreased with shock strength whereas for the strong shock case

peak frequencies, pressure and shock oscillation amplitude both increased with shock

strength. For the weak shock case the characteristic frequencies observed follow the

acoustic predictions and frequencies upto third harmonic were observed but for the strong

shock case the single characteristic frequency observed does not follow acoustic

predictions.

Forced oscillation experiments on the same model were conducted to investigate

the role of oscillations induced in inlets of Ramjets by combustor instabilities. The

pressure oscillations were simulated asymmetrically by mechanical modulation of the

diffuser cross sectional area near the channel exhaust. A triangular prism shaped rotor

was rotated to simulate excitation frequencies in the range of 15-330 Hz. The pressure

perturbation amplitudes arising from the combustor can reach upto 20% of the local mean

pressure causing the expulsion of the shock train resulting in an inlet unstart. However,

this mechanism resulted in rms intensities, which varied between 0.5- 2% of the local

static pressures. Shock displacement and pressure amplitudes decreased with increasing

frequency at all Mach numbers, although the effect was more pronounced in weaker

shock systems. In weak shock systems, the pressure and velocity perturbations behaved



4

as one dimensional acoustic waves, while the interaction of the perturbation with the

shock structure and the boundary layer is more complex compared at higher Mach

numbers. A very interesting observation was the lack of resonance conditions in the inlet,

even when the natural and excitation frequencies were equal. It was conjectured that the

method of excitation led to oscillation modes different from those existing in natural

conditions. To the existing two dimensional transonic channel, a ramp/cowl configuration

was incorporated to simulate inlet flows. Supercritical oscillations are dominated by

shock boundary layer interaction’s (SBLI) and displayed broadband spectral character,

while oscillations involving sub and non critical states, produced significant periodic

spectral contributions in dual mode and a rigorously periodic intense oscillation in the

triple mode (when the shock position range overlaps all 3 ranges of criticality, viz.

subcritical, critical and supercritical). With mechanically generated downstream

perturbations, in super critical operations the pressure varied linearly with the fluctuations

at the exit station even for large exit station amplitudes (8% of exit mean static pressure).

However, in subcritical condition, the excitation interacted nonlinearly with the naturally

present, highly periodic oscillations by either modifying the natural frequency, if the

excitation was near a natural harmonic, or by having the excitation modulate the naturally

occurring oscillation.

However, Laser Doppler Velocimeter studies by Bogar 9

on self excited

oscillations to ascertain the differences in natural and forced oscillations in the

supercritical transonic diffuser showed similar flow patterns in both excited and

unexcited inlets. It was suggested that the gross motion is a vertical oscillation of the core

flow, causing an oscillation in the boundary layer thickness. It was also inferred that the



5

separation bubble appears to be a more effective medium for propagating shock

generated disturbances downstream than the high-speed core flow.

Hongprapas et al.10

investigated the phenomenon of supersonic inlet buzz on a

generic axisymmetric, external compression inlet at a Mach number of 2.4. The model

had the provision to control the exit area in order to vary the inlet operating condition.

Varying the exit area produced steady operation for larger exit area and inlet buzz for

smaller exit area. Dailey’s type of buzz11

was observed. During buzz supersonic inlets

exhibit considerable oscillation of the shock system in front of the inlet and

corresponding large pressure fluctuations downstream. It was stated that the separated

flow inside the inlet had a substantial influence on the onset of instability.

Wie et al.12

studied a small-scale rectangular inlet at Mach 3. cowl length and

cowl height parameters were studied for their effect on the inlet starting characteristics.

Inlet unstarts were classified as “hard” or “soft.” Hard unstarts appear to occur when the

flow at the inlet throat chokes while soft unstarts occur as large-scale separation develop

within the inlet. For shorter cowls and higher cowl heights, hard unstarts are prevalent

whereas the softer unstarts occur for the longer cowl lengths and lower cowl heights. In

our present model “soft” unstarts were observed due to separation at the compression

corner at the second wedge.

Fernandez and Nenni13

performed tests on a two dimensional, mixed compression

inlet from which the present inlet of study was designed. The main flow entering the inlet

had substantial amount of boundary layer and had to be bleeded out. In the supercritical

case the cowl shock was almost perfectly cancelled by the throat shoulder with only weak



6

oblique shocks occurring in the downstream flow. The wind tunnel Mach number was 3.5

and the total pressure recovery was 0.37.

Theoretical studies were carried out, focussing mostly in transonic regimes and

Ramjet inlet/combustor interactions. These analyses mostly assumed simple geometries,

inviscid flows and small amplitude oscillations, while the solution methods involved

acoustic, asymptotic methods, and (or) linear stability analysis. Some of them were

numerical studies solving the Navier-Stokes equations for transonic/supersonic flows in

order to study the experimental results of Sajben et al.4-8

Nevertheless, results predicted

the experimental results quite accurately.

Culick and Rogers14

analyzed the stability of normal shocks in the diverging

section of inlets for Ramjet engines. The inviscid flow analysis showed that the shock

waves always attenuated the pressure fluctuations while the shock wave may act to drive

the oscillation over a broad range of low frequencies and high Mach numbers in the

viscous analysis. It was determined that stability of the normal shocks in diverging

channels could be unfavorably influenced by the separation region created downstream of

the shock. According to these results, the physical origin of the instabilities arises from a

reduction in pressure recovery due to the separated region downstream of the shock.

Hsieh et al.15-17

studied the flow field within an unsteady two-dimensional inlet.

The unsteady cases calculated were performed with exit plane pressure variations on the

order of 14% of the mean static pressure. The resulting flow field contained notable

features such as curved terminal shocks that disappeared and reformed, more than one

normal shock coexisting in the inlet at once (shock trains) and separation region

bifurcation, formation and disappearance. Unfortunately, experimental data was not



7

available to check the accuracy of the calculation. So, in order to check their assumptions

and calculations they performed numerical simulations of self excited oscillations in a

two dimensional transonic diffuser flow (experiments of the Sajben group5-9

). They

agreed well with the experimental results though qualitatively; i.e. the computation

accurately predicts the length of the separation pocket but underpredicts its thickness.

Similarly on the downstream side of the separation pocket, the experiment indicates a

fully developed channel flow, whereas the calculation features an inviscid core region.

They also investigated the unsteady flow of a two-dimensional Ramjet diffuser by

introducing unsteadiness in the form of a sinusoidal exit plane pressure disturbance with

amplitude 20% of the mean exit pressure. Both acoustic theory and small perturbation

models predict that the sinusoidal pressures at the exit plane will generate sinusoidal

velocity of the same frequency, but with altered phase angle and amplitude. But here a

sinusoidal large amplitude pressure fluctuation generates non-sinusoidal variation in exit

plane velocity and recovery pressure. However the accuracy of the calculations remains

to be determined, as the experimental data was not available for comparison.

Biedron and Adamson18

have analyzed unsteady flow through a two dimensional

supersonic diffuser with a normal shock wave using asymptotic methods. It was shown

that the low frequency back pressure fluctuation or the large amplitude fluctuations were

equally capable of causing an inlet unstart, which was detrimental to the diffuser

performance. These results also implied that separated flow can play an important role in

phenomena like self sustained shock wave oscillations.

Hsieh and Yang19

investigated the unsteady flow structures in a supersonic

Ramjet engine by treating both the internal flowfield in an axisymmetric mixed



8

compression inlet (at a Mach number of 2.1) and a coaxial dump combustor. The

calculations revealed a low frequency pressure oscillation at 135 Hz with a peak to peak

approximately at 20% of the average pressure in the combustor. The terminal shock in

the inlet diffuser oscillates at the same frequency, but out of phase with the pressure

fluctuations in the combustor, suggesting a strong coupling between inlet and combustor.

Large vortical motions, coupled with acoustic motions, were observed in the combustion

chamber, which in turn modified the inlet flow structures.

Pegg et al.20

analyzed a mixed compression inlet design concept for a PDE for the

Mach 3 condition. They simulated the operation of multi duct PDE rotary valves by an

array of four sonic nozzles (valves) in which the flow areas were rapidly varied in various

opening/closing combinations. They indicate that a terminal shock train can be stabilized

in the isolator and that the pressure perturbations and the expansion waves caused by

simulated PDE valve area changes do not disturb the terminal shock system, thereby not

effecting the inlet’s operability or performance. Computed internal inlet stagnation

pressure recovery was roughly 70%.

1.2 Motivation for Current Study

1.2.1 A New Engine Concept-Pulse Detonation Engine

The present study deals with the flowfield in a supersonic inlet of a pulse

detonation engine (PDE). PDEs are currently attracting considerable research and

development attention because they promise performance improvements over existing air

breathing propulsive devices. The drivers for all this work are the promises of high

efficiencies, lighter weight and less complexity than existing gas turbine engines21, 22

. The

ideal thermodynamic cycle efficiency is higher than that of a Brayton cycle, and the rapid

detonation processes in the PDE produce larger combustion chamber pressures thus



9

generating more thrust than the Gas Turbine engines.23, 24

The fact that the PDE has far

less moving parts than a typical Gas Turbine engine facilitates ease of maintenance and

service. If one compares a PDE system to a Ramjet system, which has a similar level of

lightweight and simplicity, the PDE has the added benefit of being able to generate static

thrust. The potential for vector thrust with no mechanical throttling motion or nozzle

adjustments is yet another advantage. In addition, PDEs can be fabricated at low cost

from off the shelf materials using standard manufacturing methods.

PDE development is still in early stages of development with many key issues to

resolve. Some of the issues concerning the development of the PDEs are: the integration

of the supersonic air induction system with the unsteady flow PDE cycle; arrangement of

the PDEs for a stable system; short, stable and repeatable ignition cycles; and good

sealing at high temperatures and pressures.

One of the primary characteristics of the PDE is the unsteady nature of the

combustion process. A representative PDE cycle of an individual pulse detonation tube

comprises of the following three phases: 22, 25

1. Filling Phase

2. Detonation Phase

3. Blowdown Phase

In the filling phase of the cycle, the fuel is injected into the duct and the right amount of

the incoming air is scooped from the flow, before the upstream valve is closed. In the

detonation phase of the cycle, the fuel air mixture is ignited initiating a detonation at the

closed end that propagates downstream. The products of combustion are pumped out of

the duct’s exhaust system in the subsequent blowdown phase. Positive axial thrust is



10

produced in phases 2 and 3.

Rarefaction waves

Detonation Initiation

Patm

V = 0 Patm

RarefactionsPatmPatm

Exhaust

PCJPCJ

Patm

P1

Rarefactions

Fuel-air mixture

PoM = 0

PatmPo VdetPo

P3

1a 1b 1c

2b 2c 3a 3b

V = 0 V = 0

V = 0

Figure 1-1. PDE cycle schematic showing the events typical of operation of a single

detonation tube.

The focus of this study was the PDE inlet. The PDE inlet is subjected to the

upstream travelling pressure and expansion waves generated by the operation of the PDE

valves. In order to reduce the effect of intermittent combustion on the air induction

system, it is necessary for the PDE module to be made up of a group, or cluster of pulse

detonation ducts that operate out of phase such that the airflow rate in the PDE module’s

common inlet duct is relatively constant. However, such configuration can cause severe

effects on the backpressure and affect the operation of the inlet including the potential of

hammershock and unstaring of the inlet. The pressure oscillations arising in the diffuser

because of the operation of the PDE valves are spatially non-uniform and periodic in

nature. A single inlet acting as a plenum for multiple detonation tubes reduces the effect

of backpressure on the inlet flow field allowing for flow transfer from the blocked

channels to the open ones. The calculations based on CFD techniques22

indicate that

during the transient flow at the inlet exit, produced by the valving system of a stack of

detonation tubes, the time available for the transfer of air between adjacent tubes is O (10

µs), which is significantly shorter than the time required to from the hammershock (O (10



11

ms)), thus supporting the plenum inlet concept. These backpressure fluctuations at the

exit of the inlet, although not causing inlet unstart, can lead to flow separation in the

diffuser, resulting in stagnation pressure losses and affecting the operation of the

detonation tubes present in the wake of the separated region.

1.2.2 Intent and Scope of Work

Most of the researches on inlet-engine interactions dealt with studies on

oscillations from the combustion chamber, wherein the oscillations were assumed to be

uniform across the cross-section of the inlet. However, the inlet of a PDE experiences

non-uniform oscillations both temporally and spatially. The present study deals with the

experimental simulation of the effects, due to the operation of an array of adjacent PDEs

on the flowfield of a supersonic inlet.

Chapter 2 describes the modeling of the backpressure excitation mechanism, the

experimental set up and instrumentation. Experimental results are reported in chapter 3

followed by the summary of the results obtained in chapter 4.



CHAPTER 2EXPERIMENTAL SETUP

2.1 Introduction

This chapter describes the supersonic inlet model, simulating the opening and

closing of the PDE detonation valves, experimental facility, instrumentation and the data

acquisition system used.

2.2 Basic Inlet Geometry

The present inlet is a modified version of the two dimensional, supersonic, mixed

compression inlet investigated by Fernandez and Nenni13

. The leading edge of the ramp

was modified as the inlet was designed to operate at a Mach number of 3.5. Figure 2-1

shows the inlet model with the 4 disturbance ports at the exit. The two-dimensional

compression system consisted of two 50

wedges on the ramp, and the cowl. The cowl is

inclined at a constant, -40

relative to the horizontal.

Plexiglass sideplates Cowl static taps

Air injection tubesExit stagnation rake

Cowl

Ramp

Static Taps onramp

Bleed Tubes

Exit injection block

Figure 2-1. Views of the inlet showing the main components and the provision for backpressure excitation.

12



13

The throat height, H is 0.2442.” The coordinates of the points, with respect to the

leading edge of the ramp that make the ramp profile are given in Table 2-1. The

contraction ratio (defined as the ratio of the areas at the throat that at the capture) is 0.6,

which is well within the self start limits at Mach 3.5, described in reference 12. The

diffuser section that follows the throat is 10.27 H long and the model is L=21.73 H long.

Table 2-1. Coordinates of points that make the ramp profile

Point X(in) Y(in) Point X(in) Y(in)

1 0 0 12 3 0.348

2 0.5 0.05 13 3.25 0.325

3 1 0.125 14 3.5 0.295

4 1.25 0.168 15 3.75 0.26

5 1.5 0.212 16 4 0.223

6 1.75 0.254 17 4.25 0.186

7 1.865 0.276 18 4.5 0.151

8 2 0.294 19 4.75 0.121

9 2.25 0.325 20 5 0.1

10 2.5 0.353 21 5.25 0.087

11 2.75 0.359

The sidewalls are made of Plexiglas to allow for full optical access. The position

of the leading edge of the cowl is such that the area of the captured stream tube is 98% of

the area of the stream tube at subsonic Mach number of 0.38. This allows a 2% spillage

of the air mass flow at the entrance. Figure 2-2 illustrates the mixed-compression inlet

with shocks occurring both outside and inside of the inlet as calculated from the oblique

shock relations. The dashed vertical line in the figure represents the geometric throat

location. However, because of viscous effects, a separation region was observed between

tap locations 1 and 3 due to which there is increased spillage at the inlet entrance. To

mitigate this problem of flow separation, bleed plenums were incorporated accordingly.



14

Figure 2-2. Shock structure as calculated from simple oblique shock relations

Figure 2-3. Inlet schematic showing the location of static pressure taps and bleed plenums

The locations of the wall static pressure taps and the bleed plenums are shown in

Figure 2-3. The bleed plenums act as low-pressure chambers and aid in the removal of

the separated boundary layer, upstream of the throat. A separation region spanning from

the location of tap 1 to tap 3 was observed. Figure 2-4 shows a picture from an oil flow

test where the flow separation region could be identified. As a consequence, the shock

angles at both the wedges increased, leading to increased spillage at the inlet entrance.

Moreover, the efficiency of the inlet would go down due to the accompanied stagnation

pressure losses. The bleed locations are at X/L=0.276 and X/L=0.427, where X/L is the

non-dimensional axial coordinate measured from the leading edge of the inlet. Three



15

rows of 0.01” diameter holes (20 holes per row) were drilled on the ramp surface as

shown in Figure 2-5. The air from these holes was then emptied into a bleed plenum,

which was connected to the vacuum line outside the wind tunnel through a set of Tygon

tubes. The total area of the bleed holes is 0.00945-in2. An estimated amount of 6% of the

inlet capture is bleeded out

Flow Separation

region

Figure 2-4. Oil flow test on the ramp.

The geometric throat of the inlet is located between the taps 5 and 6. The

distances of the static pressure ports from the leading edge of the inlet normalized with

the length of the inlet are given in Table 2.2. Static pressure measurements were also

taken on the cowl at 4 locations corresponding to the last 4 taps on the ramp to compare

and check if there was any discrepancy in the pressure distribution, aft of the terminal

shock in the separated region. The static taps on the ramp lie along a common axis, which

is at a distance of 0.4125” from the inlet centerline. This had to be done so that the inlet

could be well supported by the sting passing through the inlet centerline.

The inlet exit is also a crucial factor as the exit pressure (backpressure) dictates

the flow characteristics in the inlet. The backpressure can be manipulated by blocking the

flow exit accordingly. For this purpose an exit injection block was used, which also had



16

provision for air injection. Initially an injection block with 4 circular holes whose total

area was 20% more than the calculated area that required to choke the flow at the exit

Figure 2-5. Top view of the ramp showing the bleed holes and the static tap locations.

Table 2.2 Location of wall static pressure taps.

Tap X / L Tap X / L

1 0.226 7 0.66

2 0.321 8 0.735

3 0.396 9 0.811

4 0.471 10 0.886

5 0.547 11 0.9626 0.584

was used. Incidentally, this area requirement made the diameter of the circular holes very

close to the height of the exit section. It was observed that this arrangement increased the

backpressure to such an extent that it unstarted the inlet, which is undesirable for the

engine operation. So, a two-dimensional injection block was made with the same exit

area requirement as that of the injection block with 4 circular holes. This block has a

converging section, which brings down the area from that of the inlet exit to the required

injection block exit area. Even this arrangement caused an inlet unstart, because of which

the injection block exit area was increased by 25%. This enabled the inlet to start and a



17

terminal shock was observed at X/L~0.73. AutoCAD drawings for both the injection

blocks are shown in Figure 2-6.

(a)

(b)

Figure 2-6. CAD drawings. (a) the injection block with 4 circular holes and (b) the two-dimensional injection block.

2.3 Backpressure Excitation Mechanism

The purpose of this study was to simulate the effect of pressure oscillations

arising from the opening and closing of the PDE valves. When there are a stack of PDEs,

each operating at different phases but drawing air from the same inlet, the pressure

perturbations at the exit vary both in space and time. In previous studies, these



18

oscillations at the exit were simulated by mechanically varying the exit area2, 3, 5-9

. In the

present study fluidic injection was used to simulate these perturbations. The present inlet

(derived from an existing NASA inlet13

) was designed such that the flow was supersonic

throughout with an oblique shock train terminating well beyond the geometric throat. The

airstream entering the detonation chambers has to be low subsonic for efficient operation

of the PDE. An injection block was mounted at the exit of the inlet as a means of

blocking the flow, thereby increasing the backpressure, which, in turn produces a normal

shock downstream of the throat, and decelerates the flow to subsonic speeds. Moreover,

the injection block also housed the air disturbance ports, which were located at the 4

corners of the exit cross section of the inlet. Air is injected along the diagonals of the

rectangular exit cross section Figure 2-7 shows the injection block as viewed from the

front and as viewed from the back.

Figure 2-7. Frontal and rear view of the exit injection block.

The intent is to parametrically vary the operation of these disturbance ports to

observe as to how the inlet reacts to periodically varying pulsed disturbances. Air

injection through the inlet exit corers was done in the configurations shown in Figure 2-8.

The words injection configuration and coupling are used interchangeably. Note that (1,2)

means that port 1 and 2 inject air in phase. The operating frequency of any port was the

same and was either 5 Hz or 10 Hz depending on the test conditions.



19

1 2

3 4

Figure 2-8. Illustration of the exit injection block with the port designations and the

injection configurations below.

1. Antisymmetric-1 (AS-1) coupling. Ports (1,2) inject air.

2. Antisymmetric-3 (AS-3) coupling. Ports (3,4) inject air.

3. Symmetric-1 (S-1) coupling. Ports (1,3) inject air.

4. Antisymmetric-2 (AS-2) coupling. Ports (1,2) and (3,4) inject air, 1800 out of phase.

5. Symmetric-2 (S-2) coupling. Ports (1,3) and (2,4) inject air, 1800

out of phase.

6. 900

phase offset (90 Phase) coupling. Each port injects air at 900

out of phase with the

neighboring ports.

Figure 2-9 depicts the layout of the air injection mechanism. Air was supplied

from an Industrial grade Nitrogen cylinder (2500 psi). The airstream is then split into 4

paths along which it is filtered using inline filters, and then recombined back into a single

stream using the manifold as shown in the figure. This filtered air is then led through a

TESCOM regulator. The outlet of the regulator is connected to a manifold. A set of 4

solenoid valves is connected to this manifold with the help of 4 Rubber hoses. These set

of solenoids are used to inject air into the inlet through the disturbance ports. We also

find another set of 4 solenoids, which are connected to a vacuum line (2” ID Galvanized

Iron pipe). The air in the vacuum line is removed using a vacuum pump (capacity of ~0.7

SCFM) and pressures as low as 0.5 psi can be obtained in the vacuum line. Each of the

disturbance ports in the back body is connected via a Teflon tube, to an injection solenoid

and a vacuum solenoid. Pressure transducers were installed along the injection solenoid



20

line to measure the pressure upstream and downstream of the injection solenoid. From

these measured pressures and the known Cv of the injection solenoid the amount of mass

injected per solenoid can be estimated. The plan was to use the vacuum solenoids to

“start” the inlet (which might be difficult with the exit blockage) and then initiating the

pulsed disturbances at the exit, with the injection solenoids. The amplitude of the

oscillations is directly related to the flow rate of the injected air. Changing the regulator

setting varies the flow rate. Frequency and coupling of the injection solenoids were

varied using a pulse generator circuit that is described in the next section.

The pulse generator circuit can be considered as the heart of the backpressure

excitation system. The circuit diagram is shown in Figure 2-10. This circuit modifies the

signal from a Leader LFG-1300S Function Generator and then converts this modified

signal into the opening and closing of the solenoid valves. The Leader LFG-1300S

Function Generator is adjusted to produce a square wave with a 50% duty cycle. The

NTE 7493A (4-bit counter), the NTE 7404 (NOT gate) and the NTE 7408 (AND gate)

TTL chips change the frequency of the square wave and produce 4 output signals with

900

phase offset state. These outputs are connected to a set of 4 OAC-5 P&B solid state

relays which energize the injection solenoid valves accordingly. The analog signal from

the computer determines the operation of either the vacuum solenoids or the injection

solenoids. Relay 1 and Relay 2 (both general-purpose relays) are activated by 2.7 volt and

8.3 volt signal respectively. Relay 1, when activated, connects the square wave signal

from the Function Generator into the TTL circuit. Relay 2 supplies the AC power to both

sets of injection and vacuum solenoids. Both Relay 1 and Relay 2 should be activated in



TESCOM Regulator

Pin=3000psi, Pout=150psi S

4 x Injectionsolenoids

Backbody connectedto the Inlet

Pressure Manifolds

3/8” OD, 1/4” ID Teflon tubes.

Operating pressure=250 psi.

4 x Vacuum Solenoids

ASCO; Cv=3

2” G.I Pipe

To Vacuum tank

Figure 2-9. Layout of the key components of the air injection mechanism



22

sets of injection and vacuum solenoids. Both Relay 1 and Relay 2 should be activated in

order to open and close the injection solenoid valves accordingly. The vacuum solenoid

valves open when Relay 2 is deactivated. The transistor circuits were made to amplify the

current of the analog signal so as to activate the relays. Thus, changing the frequency

setting on the Function Generator and by clubbing the signal outputs from the TTL

circuit, the desired changes in frequency and the coupling of the injection solenoids could

be produced. Two frequencies of excitation were attempted: 5 Hz and 10 Hz. The

response of the solenoids deviates from the input square wave for frequencies higher than

20 Hz.

2.4 Description of the Wind Tunnel

The tests were carried out in the Mach 4 wind tunnel at the Department of MAE

at the University of Florida. The test section Mach number can be varied from 1.5 to 4.

The wind tunnel has a sliding lower wall made of aluminum block and mounted on a

worm gear. The position of the lower wall can be changed, affecting the throat area of the

wind tunnel throat, for different test section Mach numbers. The test section Mach

number is calibrated with a block position counter. In our case, the counter setting of 390

produces the desired test section Mach number of 3.5. The minimum stagnation pressure

required to attain this Mach number of 3.5 is 120 psi.

Two large external tanks act as reservoirs of high-pressure air for the blow down

tests. A 750 hp Quincy compressor supplies air to the reservoirs. The compressor can

compress the air to a maximum pressure of 225 psig. All the tests were run at Mach 3.5

and the available run time was about 25s.



R

R

Vcc=12 V

120 V AC line120 V AC line

120 V AC line

4 x Vacuum Solenoids

120 V AC Neutral

4 x Injection Solenoids

120 V AC Neutral

LFG-1300SSquare wave, dutyc cle 50% F Hz

Vcc=12 V

Relay 1

2.7 V Analog Signal

NTE 7493

4 bit counter TTL Circuit

NTE 7404 NOT Gate

NTE 7408

AND Gate

Figure 2-10. Schematic of the pulse generator circuit.



24

The stagnation pressure is controlled by a pneumatically operated spring-loaded

butterfly valve. A valve positioner supplies the required actuating pressure to the valve

mechanism. The valve positioner has PID logic to determine the amount of actuating

pressure that must be supplied to the valve mechanism depending on the input pressure

supplied to the postioner. The input pressure to the valve postioned is in turn supplied by

a TESCOM ER3000 electronic regulator, which also is based on PID logic. The output of

the electronic regulator can be controlled by computer commands via a serial port. A

nitrogen cylinder supplies the actuating fluid to both the ER3000 electronic regulator and

the valve positioner. The computer issues a set-point to the ER3000in the range between

400 (no output) and 3700 (maximum output). Based on this input, the ER3000 regulates

its output pressure, which acts as a set-point pressure for the valve positioner. The valve

positioner then tries to match its output pressure to the set-point pressure. This output

from the valve positioner acts on the dome-based regulator that drives the butterfly valve

mechanism. Figure 2-11 shows the schematic of the tunnel valve control.

The test section is 6” x 6” in cross section and 18” in length, with a near constant

cross-section. Optical access is provided with two 0.5” thick glass windows on the

sidewalls of the test section. The model is mounted on a C-shaped sting and the angle of

attack can be varied from –10o

to +10o

with an accuracy of 0.1o.

2.5 Instrumentation

The wall pressures were measured by using a Pressure SystemsTM

PSI 9010

Scanner and OmegaTM

PX-303 transducers. The PSI 9010 has 16 pressure ports with a

range of 0-10 psia (ports 1-4), 0-45psia(ports 5-9), 0-100psia(ports 10,11) and 0-250 psia

(ports 12-16). The PSI 9010 communicates with the serial port and the number of



25

Figure 2-11. Schematic of tunnel valve control.26

samples that are averaged before reading out the data can be set in the hardware. The

maximum scan rate reading all channels is 10 Hz and this can be increased by decreasing

the number of channels that are read. Scanner ports 5-15 were used for data acquisition

and the scan rate increased to 25 Hz, thereby capturing the pressure oscillations up to

12Hz. A National Instruments AT-MIO-16-E2 data acquisition card was used on a

Pentium II – 266 MHz computer. The card can read 16 differential inputs at a maximum

rate of 500 kHz at a maximum cumulative scan rate of 500 kHz. Two analog output

channels on the AT-MIO-16-E2 board were used to activate the Relays in the Pulse

Generator circuit. The tunnel control and data acquisition was done by a program written

in LabVIEW. The software with the relevant programs in LabVIEW are explained in

detail in Appendix A. A Matlab program was used to compile the data and for further

data reduction to produce the plots. The MATLAB program is included in Appendix B.



26

2.6 Schlieren Setup

To visualize the flowfield in the inlet, a schlieren system was set up. The

schematic of the schlieren is shown in Figure 2-12. A Mercury short arc lamp was used

as the light source and this lamp is different from the other short arc lamps, as it should

be mounted with the anode at the base, for better arc stability and longer life. The

schlieren images were recorded by a SONY camcorder. The limitation of the schlieren

system is that it produces an image, which is an integrated effect of the deflections

undergone by the light beam travelling through the flow. So, this technique is a powerful

tool in visualizing two-dimensional flows, from which we can make quantitative

estimates, for e.g., the oblique shock angles, the position of the normal shock etc.

2.7 Oil Flow Visualization

This technique serves for visualizing the flow pattern close to the surface of a

solid body exposed to airflow. The observed pattern can indicate the positions of

transition from laminar to turbulent flow in the wall boundary layer, and the positions of

the flow separation and reattachment. The surface of the ramp was coated with an oil-

based paint (white pigment) to determine the regions of separation if any.



27

Hg arc lamp

Converging lens

6” collimating mirror

Figure 2-12. Schematic of the schlieren system.26



CHAPTER 3RESULTS

3.1 Introduction

The purpose of this study was to simulate the effects of combustion tube

detonations due to a pulse detonation engine on the inlet, at a free stream Mach number

of 3.5. The backpressure fluctuations were produced by injecting air from the corners at

the exit cross section, into the inlet . The following effects were the focus of this study:

• Mass flow injected into the inlet.

• Injection configurations, which corresponds to the inlet response to periodic, variable

spatial blockage.

• Frequency of air injection. Two frequencies, 5 Hz and 10 Hz, were attempted.

Wall static pressures were measured at eleven different streamwise locations along the

inlet. Stagnation pressure measurements were taken at the exit of the inlet with a

stagnation pressure rake having three probes. The probes were stacked one over the other

and spaced equidistantly. Static pressures were measured aft of the terminal shock both

on the cowl and the ramp simultaneously in selected experiments. Schlieren images were

taken during tests.

3.2 Flow Field Inside the Inlet

3.2.1 The Supersonic Inlet

The present inlet was derived from a scaled down version of an existing NASA

inlet13

, which was designed for hypersonic Mach number of 6. The flow was fully

supersonic inside the inlet, as can be seen from the values of static pressures in Figure 3-

1.

28



29

3.2.2 The Supercritical Inlet

The PDE inlet has to decelerate the flow to low subsonic before feeding it to the

detonation tubes. Therefore, the inlet has been modified to operate supercritically with

subsonic exit flow, as required by PDE. Thus, a normal shock appeared in the diffuser. A

typical wall pressure distribution is included in Figure 3-1 for comparison with the

supersonic inlet. In both cases, boundary layer suction was actively done from the ramp

(see Figure C-2 in Appendix C) at locations X/L=0.276 and X/L=0.427, where X/L is the

non-dimensional axial coordinate measured from the leading edge of the inlet. Figure 3-

2a, shows the shock patterns set up both outside and inside of the inlet and Figure 3-2b

shows the zoomed-in picture of the normal shock in the diffuser for the non-injection

case. Figure 3-2b clearly indicates that the shock is partly normal and terminates as a

lambda shock on both the cowl and ramp walls. Therefore, the pressure rise across the

shock is about 50% of the value calculated for a normal shock that occupies the entire

cross section. The terminal shock in the inlet occurs at the location X/L ~ 0.73.

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 Supersonic Inlet

Current, Supercritical Inlet

Figure 3-1. Comparison of mean static pressures in the inlet for the blocked and the

unblocked configuration.



30

(a) (b)

Cowl

Ramp

Figure 3-2. Schlieren images. (a) The entire flowfield within the inlet without injection.(b) Zoomed in view of the terminal shock structure. The shock occurs at

X/L~0.73.

From the Figure 3-1 it can be inferred that the static pressure rise in the inlet,

defined as the ratio of the exit static pressure to the freestream static pressure, is about 15.

The inlet was operated at a backpressure ratio (ratio of mean backpressure to the

freestream stagnation pressure) of 0.2.

3.3 Preliminary Calibration

Static pressure measurements were taken on both the cowl and the ramp surfaces

at the locations immediately after the normal shock to check if there were any

discrepancies in the static pressure profile downstream of the normal shock, due to the

shock induced separation region. Figure 3-3a and b compares the mean normalized static

pressures measured on the ramp and the cowl for both the non-injection and the injection

case. In the injection case, 90 phase coupling injecting 39% of the inlet capture and

operating at a frequency of 5 Hz was used.

It can be seen that the static pressure measurements on the cowl and the ramp

agree, but with variation at X/L=0.89. In general, the static pressures measured on the



31

cowl are little bit lower than those measured on the ramp, in the non-injection case. This

may be due to the difference in shock strength along the shock, which can be imagined

(a) X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10.05

0.1

0.15

0.2

0.25 Ramp

Cowl

(b) X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10.05

0.1

0.15

0.2

0.25 Ramp

Cowl

Figure 3-3. Comparison between the ramp and the cowl mean normalized static pressures. (a) Non-injection case and (b) Injection case.

from the different degree of flow separation from the cowl and the ramp side as shown in

Figure 3-2b. In the Injection case, the shock moves upstream and thus becomes relatively

weak and therefore there is a better agreement between the cowl and the ramp static

pressure profiles in Figure 3-3b. All the static pressure measurements shown in the

following data were recorded from the ramp.

3.4 Static and Stagnation Pressure Measurements

Experiments were carried out with the following conditions:

• Six different injection configurations (as discussed in Chapter-2).

• Two different injection mass flows- 20%, 40% of inlet capture.

• Two different frequencies -5 Hz, 10 Hz.

The mass is given as a percentage of the capture mass flow. In each experiment the

injection began when the wind tunnel stagnation pressure reached a steady value of 120

psia. At this tunnel stagnation pressure the inlet capture mass flow is 0.2kgs-1

.



32

A stagnation pressure rake located at the exit section of the inlet measured

stagnation pressure. The rake had three probes stacked one over the other, which

measured stagnation pressure at Y* = 0.145,0.5 and 0.855 at the exit section. Y* is the

non-dimensional distance of the probe location from the ramp i.e.,

*0.3378

yY =

Where y is the distance of the probe from the ramp and the distance from the cowl to the

ramp is 0.3378”.

Figure 3-4 shows the exit injection block with the stagnation rake embedded in it.

The rake designations are also shown. The results obtained from the stagnation pressure

measurements are presented in section 3.4.4.

Cowl side probe

Ramp side probe Core probe

Figure 3-4. Views of the exit injection block with the stagnation pressure rake embedded

in it with the probe designations.

3.4.1 Effects of Injection Configuration

For a given injection mass flow and backpressure excitation frequency, the effect

of injection configuration on the inlet characteristics could be inferred. The 20% mass

injection and 5 Hz backpressure excitation frequency case is considered for comparing

the pressures in the unexcited inlet with those measured in the inlet during the injection



33

phase and for comparing the injection configurations as well. The assignment of exit

injection block ports, injection configurations and their abbreviations are discussed in

Chapter 2. S-2 coupling and 90 Phase coupling are considered for comparing the

unexcited inlet with that of the excited inlet and the plots shown in Figure 3-5. In cases of

Figure 3-5a and b, the first and the third plots, graph the normalized mean wall static

pressure and the fluctuation of static pressure with X/L. The fluctuation of static pressure

( ) is defined as the difference between the maximum ( P ′ Peak P ) and minimum ( )

pressures attained, to the average pressure ( ) during injection i.e.,

valley P

avg P

( ) peak valley

avg

P P P

P

−′ =

In the plots of the center column, the ordinate Y* is plotted with the normalized mean

stagnation pressure. Both the mean static pressure and the mean exit stagnation pressure

were normalized with the freestream stagnation pressure. Figure 3-7 gives the plots,

which compare the selected injection configurations.

From Figure 3-5 it can be observed that the mean levels of static pressures

downstream of the throat in the excited inlet are higher than the corresponding ones of

the unexcited inlet. The same trend is observed with the pressure oscillations produced in

the inlet. The stagnation pressure at the exit also changed because of the terminal shock

oscillations. The exit stagnation pressures follow the typical trend in that the pressure

values are lower near both the cowl and ramp walls and increasing from the walls to the

center section. It is also observed that the ramp side stagnation pressure is always lower

than the cowl side measured stagnation pressure because of the greater degree of



34

separation on the ramp side. All these phenomena can be attributed to the large-scale

terminal shock oscillations generated in the excited inlet.

Figure 3-6 compares the schlieren images for the unexcited and the excited inlets

for the S-2 and the 90 Phase injection configurations. The flow direction is from the left

side to the right. The sidewalls of the inlet, made of 0.25” Plexiglas, have beveled leading

edges to facilitate smooth airflow past them and prevent bow shocks from forming at the

entry of the inlet. These beveled regions being opaque to light appear as dark bands along

the left edge of the images. The thin tubes seen in the images are the 1/16” OD SS tubes

used for static pressure measurements while the thicker tubes are the 1/8” ID SS tubes

used for boundary layer suction. Images were taken by a SONY camcorder, which had a

frame rate of approximately 30 Hz. So, on an average 6 images were acquired during a

period of the injection cycle with excitation frequency of 5 Hz. Schlieren movies are

presented in Appendix-D to further supplement the information provided here. There was

a relative terminal shock displacement in the excited inlet when compared to the

unexcited inlet, which can be clearly seen in both the cases considered. The weakening of

the terminal shock, as it moves upstream in the excited inlet, can be observed. It can be

inferred that the shock induced separation region moves with the oscillating terminal

shock.

For understanding the effect of injection configuration on the static pressure and

stagnation pressure at the exit, Figure 3-7 is considered. From Figure 3-7a it can be

observed that the AS-2 and the S-2 injection configurations produced almost identical

levels of static pressure, stagnation pressure at the exit and their associated oscillations,



S-2 Coupling

(a)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 Without Injection

With Injection (5 Hz - 18.5%)

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1 Without InjectionWith Injection (5Hz - 18.5%)

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.6 0

0.2

0.4

0.6

0.8

1 During Injection

90 Phase Coupling

(b)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 Without InjectionF=5 Hz, Minj= 23%

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1 Without Injection

F=5Hz, Minj= 23%

X / L

( P

p

- P v ) / P a v

0 0.2 0.4 0.6 0

0.2

0.4

0.6

0.8

1 During Injection

Figure 3-5. Plots for comparing the excited and the unexcited inlet, for Minj=20% and Frequency = 5 Hz



36

(a)

Unexcited Inlet Excited Inlet

(b)

Unexcited Inlet Excited Inlet

Figure 3-6. Schlieren images for the 5 Hz and 20% mass injection. (a) 90 Phase coupling

(b) S-2 coupling.



37

during injection. The same is true with the AS-1, AS-3 and the S-1 injection

configurations as can be deduced from Figure 3-7b and c. The AS-2 and the S-2

configurations generated larger mean static pressures and their associated oscillations and

larger mean exit stagnation pressures, when compared to the AS-1, AS-3 or the S-1

configurations, as can be inferred form Figure 3-7d. But the differences in the fluctuation

Vs X/L plot for the S-2 coupling and S-1 coupling, as shown in Figure 3-7d can be

attributed to the differences in the mean pressure levels attained in the respective

injection configuration. The AS-2 and the S-2 configurations produced shock oscillations

whose effects propagated farther upstream than those of the AS-1, AS-3 or the S-1

couplings, as can be deduced from Figure 3-7d. The differences may be due to the fact

that in the AS-2 and the S-2 coupling configurations, air is injected from all the ports in

the exit injection block, which may have caused larger degree of shock displacement, and

thus all the observed effects. From Figure 3-7e, it can be inferred that among all the

injection configurations, the 90 Phase configuration produced the largest levels of mean

static pressure in the inlet. It was interesting to observe that the 90 Phase coupling

produced the lowest levels of shock oscillations and, therefore pressure oscillations. For

example, considering Figure 3-7f, the rms intensities reached to a maximum of 7%of the

local mean static pressure in the case of 90 Phase coupling while a maximum of 25% was

attained in the case of Symmetric and the Antisymmetric couplings.



S-2 & AS-2 Configurations

(a)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 S-2AS-2

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 S-2AS-2

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1S-2AS-2

AS-1 & S-1 Configurations(b)

X / L

p / P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 AS-1

S-1

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 AS-1

S-1

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1 AS-1

S-1

Figure 3-7. Comparing the effects of injection configuration on the inlet flowfield.



AS-1 & AS-3 Configurations

(c)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 AS-1AS-3

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 AS-1AS-3

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1AS-1AS-3

S-2 & S-1 Configurations(d)

X / L

p / P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 S-2

S-1

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 S-2

S-1

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1 S-2

S-1

Figure 3-7 (contd.). Comparing the effects of injection configuration on the inlet flowfield.



90 Phase and AS-2 Configurations

(e)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 90 PhaseAS-2

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 90 PhaseAS-2

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

190 PhaseAS-2

90 Phase and S-1 Configurations(f)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 90 Phase

S-1

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 90 Phase

S-1

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1 90 Phas

S-1

Figure 3-7 (contd.). Comparing the effects of injection configuration on the inlet flowfield.



41

3.4.2 Effects of Mass Injection

In the present work, the effects of injecting different quantities of mass into the

inlet were investigated as well. For a given injection configuration and backpressure

excitation frequency, the effects due to variation in injected mass flows, on the inlet

characteristics could be inferred. In the present study the injection mass flows of 20% and

40% are compared. The plots for all the 6 Injection configurations at a backpressure

excitation frequency of 5 Hz are shown in Figure 3-8. In figure 3-8a, for the 90 Phase

coupling increased quantities of mass injection leads to an increase in the mean levels of

static pressure downstream of the throat. Its interesting to note that the oscillations

produced in the 40% case are either equal or less than those produced in the 20% case.

Interestingly for the other injection configurations, as in figure 3-8b-f, the mean levels of

the static pressure are almost identical for both the injection flow cases. Nevertheless, for

the 40% case, large pressure oscillations are generated and the effect is clearly felt in the

static taps upstream of the throat, for all the Antisymmetric and Symmetric

configurations. Thus, in general, the 20% injection case produced pressure oscillations,

which were confined to the downstream of the throat, whereas the 40% injection case

produced oscillations, which effected the static pressure all the way up to the capture.

This can be clearly visualized by comparing the fluctuation Vs X/L plots for both the

cases. In the 40% case a small drop in pressure could be observed in the first three static

taps during injection. This was due to the increased spillage in the 40% injection case and

the accompanied weakening of the leading edge wave system, which can be clearly

observed in the schlieren images, as discussed below.

Figure 3-9 compares the schlieren images for the 20% and the 40% injection case,

with the aid of S-2 and 90 Phase injection configurations respectively. The flow direction



42

is from the left side to the right. From the schlieren images, the increased spillage and the

weakening of the capture wave system, in the 40% case can be clearly seen. Schlieren

movies are presented in Appendix-D to further supplement the information provided

here. In the schlieren movies of Appendix-D, one can clearly see the increased spillage,

during injection for the 40% case, in all the injection configurations. In almost all cases,

except the 90 Phase coupling, the terminal normal shock is periodically expelled from the

inlet, during the injection cycle.

The effect of mass injection on the exit stagnation pressure is not significant. In

all the injection configurations a slight drop in the exit stagnation pressure in the ramp

side probe and the core probe can be observed in the higher mass injection case when

compared to the lower mass injection case, in Figure 3-8. For the 40% case, though the

increased spillage weakened the shocks and the expansion waves in the inlet, the large

mass of relatively low momentum fluid into the inlet has a negative effect on the exit

stagnation pressure. But the compensating effect is provided by the upstream moving

normal shock and thus the exit stagnation pressure is the net resultant of these effects. For

the 20% case, as there was negligible or no spillage, only the effect of the upstream

moving normal shock is dominant and thus the level of the mean stagnation pressures at

the exit relatively increased during injection in all the injection configurations. This was

due to the weakening of the shock as it moves upstream in the diffuser section, as it

encounters a lower relative Mach number.



90 Phase Coupling

(a)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 F=5 Hz, Minj=39%F=5 Hz, Minj=23%

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 F=5 Hz, Minj=39%F=5 Hz, Minj=23%

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1F=5 Hz, MF=5 Hz, M

AS-2 Coupling(b)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 F=5 Hz, Minj=39%

F=5 Hz, Minj=18.5%

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 F=5 Hz, Minj=39%

F=5 Hz, Minj=18.5%

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1 F=5 Hz, M

F=5 Hz, M

Figure 3-8. Comparing the effects of mass injection for two different injection mass flows-20% and 40%



S-2 Coupling

(c)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 F=5 Hz, Minj=39%F=5 Hz, Minj=18.5%

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 F=5 Hz, Minj=39%F=5 Hz, Minj=18.5%

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1F=5 Hz, MF=5 Hz, M

S-1 Coupling(d)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 F=5 Hz, Minj=39%

F=5 Hz, Minj=19.5%

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 F=5 Hz, Minj=39%

F=5 Hz, Minj=19.5%

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1F=5 Hz, Minj=39

F=5 Hz, Minj=19

Figure-3.8 (contd.). Comparing the effects of mass injection for two different injection mass flows-20%



AS-1 Coupling

(e)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 F=5 Hz, Minj=39%F=5 Hz, Minj=19.5%

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 F=5 Hz, Minj=39%F=5 Hz, Minj=19.5%

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1F=5 Hz, MF=5 Hz, M

AS-3 Coupling(f)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 F=5 Hz, Minj=39%

F=5 Hz, Minj=19.5%

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 F=5 Hz, Minj=39%

F=5 Hz, Minj=19.5%

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1 F=5 Hz, M

F=5 Hz, M

Figure-3.8 (contd.). Comparing the effects of mass injection for two different injection mass flows-20%



46

S-2 Coupling

(a)

40% Mass injection 20% Mass injection

90 Phase Coupling

(b)

40% Mass injection 20% Mass injection

Figure 3-9. Schlieren images for comparing the 20% and 40% mass injection cases.

Figure 3-10 and Figure 3-11 show the staggered plots of the time trace of the

static pressures, normalized by the freestream stagnation pressure, at all the static tap

locations along the inlet for both the non-injection case and the injection case. In Figure

3-10, AS-2 coupling, injecting 20%, operating at 5 Hz is considered while in Figure 3-11,



47

AS-2 coupling, injecting 40%, operating at 5 Hz is considered. Figure 3-10 indicates that

the upstream static ports 1-4 are virtually uneffected by 20% mass injection. From the

plots of Figure 3-11, it can be seen that the upstream static taps 1-4 are effected for the

40% mass injection case. It can be observed that the induced oscillations have a

fundamental frequency that matched the excitation frequency.

Figure 3-10. Static pressure –time trace for the AS-2 coupling, 20% mass injection and 5

Hz case.



48

Figure 3-10 (contd.). Static pressure –time trace for the AS-2 coupling, 20% mass

injection and 5 Hz case.



49

Figure 3-11. Static pressure –time trace for the AS-2 coupling, 40% mass injection and 5

Hz case.



50

Figure 3-11 (contd.). Static pressure –time trace for the AS-2 coupling, 40% mass

injection and 5 Hz case.

3.4.3 Frequency Effects

Tests were conducted with the same injection mass flow i.e., 20% of the inlet

capture, but with different excitation frequency for three representative injection

configurations namely the 90 Phase coupling, AS-2 and the S-2 coupling. So, for a given

injection configuration and the same given injection mass flow, effect of excitation

frequency on the stability of the inlet could be understood.



51

Figure 3-12a, b and c compare the effects produced by the excitation frequencies

5 Hz and 10 Hz on the inlet flowfield. The change in excitation frequency has a direct

effect on the magnitude of the static pressure oscillations as can be seen in Figure 3-12.

In all the injection configurations considered here the 5 Hz excitation case produced

larger pressure oscillations than the 10 Hz case as can be seen in the fluctuation Vs X/L

plots of Figure 3-12. The change in frequency did not have any significant effect on the

mean pressure levels on the AS-2 and S-2 configurations considered but the higher

injection mass flow in the 5 Hz case produced slightly higher mean pressure levels for the

90 Phase coupling.

The mean exit stagnation pressure in the 10 Hz case was higher when compared

to those in the 5 Hz case, for all the injection configurations, as shown in Figure 3-12. It

can be observed that the ramp side stagnation pressure measurement is the same in all

cases. The movies in Appendix-D show that the terminal shock displacement on the ramp

is the same for both 10 Hz and 5 Hz cases but the curvature of the shock increases on the

cowl side for the 10 Hz case thereby increasing the pressure recovery on the cowl side

and the core stagnation probes.

3.4.4 Exit Stagnation Pressure

The injected configuration, the amount of mass injection and the backpressure

excitation frequency, as discussed in the previous sections, effected the exit stagnation

pressures. But the mean stagnation pressures in the excited inlet was not appreciably

different from the unexcited inlet. Mean total recovery of 0.3 and 0.32 were produced in

the unexcited and the excited inlet respectively. The mean total recovery is defined as the

mean of the normalized exit stagnation pressures measured with the rake. This low



90 Phase Coupling

(a)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 F=10 Hz, Minj=20%F=5 Hz, Minj=23%

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 F=10 Hz, Minj=20%F=5 Hz, Minj=23%

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1F=10Hz, MF=5 Hz, M

AS-2 Coupling(b)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 F=10 Hz, Minj=20.7%

F=5 Hz, Minj=18.5%

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 F=10 Hz, Minj=20.7%

F=5 Hz, Minj=18.5%

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1 F=10Hz, M

F=5 Hz, M

Figure 3-12. Comparing the effects of two different excitation frequencies-5 Hz & 10 Hz.



S-2 Coupling

(c)

X / L

p

/ P o 1

0 0.2 0.4 0.6 0.8 10

0.05

0.1

0.15

0.2

0.25 F=10 Hz, Minj=20.7%F=5 Hz, Minj=18.5%

Po / Po1

Y

*

0 0.1 0.2 0.3 0.4 0.50

0.2

0.4

0.6

0.8

1 F=10 Hz, Minj=20.7%F=5 Hz, Minj=18.5%

X / L

( P p

- P v ) / P a v

0 0.2 0.4 0.60

0.2

0.4

0.6

0.8

1F=10Hz, MF=5 Hz, M

Figure-3.12.(contd.) Comparing the effects of two different excitation frequencies-5 Hz & 10 Hz.



54

pressure recovery is a result of both the shock system losses and existence of large

separation zones in the inlet. A separation bubble on the second wedge, near the inlet

capture and the separation regions aft of the terminal shock are the primary separation

zones, which could be identified. Experiments on a similar inlet by Fernandez et al.13

produced a total pressure recovery of 0.37. The inlet used in their experiments has

variable geometry with adjustable ramp and cowl. Moreover the inlet was larger than the

inlet of the present study and thus has relatively lower losses.

3.5 Implications of Design and Size

The vehicle’s flight envelope largely dictates the design of the inlet. The size of

the inlet is dependent on the size of the vehicle and its mission. The size of the current

inlet would be comparable to that in a typical missile and hence the performance. The

size of the inlet would have been larger in the case of an aircraft. It would be expected

that in a larger size inlet, separation zone at the leading edge would be less severe leading

to an improved performance when compared to the current one. Furthermore, for

extended mission, bleed control may be employed reducing the adverse separation

effects.



CHAPTER 4SUMMARY

The present study evaluated the effects of mass injection in a supercritical inlet for PDE

at Mach number of 3.5. The air injection simulated the operation of several PDE tubes

placed at the inlet exit. Effects of amount of mass injected, the excitation frequency and

the injection configurations have been evaluated. The results indicated the following.

• A terminal normal shock in the diffuser induced separation on both the cowl and the

ramp. The shock is partly normal and terminates as a lambda shock on both the cowland the ramp walls. As a result the pressure rise is half of the theoretical estimate.

• A separation bubble was noted on the second wedge, which disrupts the flow and

caused a complex shock and expansion wave system.

• There was good agreement between the ramp and the cowl static pressure

measurements aft of the terminal shock.

• In general, terminal shock oscillations were observed due to air injection and the

mean levels of static pressure downstream of the throat increased during injection.

• Large amplitude pressure oscillations were observed and rms intensities as high as

25% of the local mean static pressure were attained in the Symmetric and theAntisymmetric injection configurations.

• Even when a substantial amount of the inlet capture mass was injected, i.e., 40% of

capture, the inlet remained started, though with increased spillage.

• For a given injection mass flow and excitation frequency, the 90 phase coupling

produced the lowest levels of pressure oscillations but interestingly produced thelargest levels of mean static pressure downstream of the throat, in the inlet when

compared to the Antisymmetric and the Symmetric injection configurations.

• For a given injection mass flow and excitation frequency, the Symmetric-2 and theAntisymmetric-2 injection configurations produce similar mean levels of static

pressure through out the inlet during injection. The same is true with theAntisymmetric-1, Antisymmetric-3 and the Symmetric-1 couplings, but the meanlevels of static pressure produced in these cases is slightly less than those produced by

the Antisymmetric-2 and the Symmetyric-2 couplings.

• For a given injection mass flow and excitation frequency, the Antisymmetric-2 and

the Symmetric-2 produced shock oscillations whose effects propagate farther

55



56

upstream than those of the Antisymmetric-1, Antisymmetric-3 and the Symmetric-1

couplings.

• For a given excitation frequency, the 20% injection case resulted in pressureoscillations, which were confined to the downstream of the throat, whereas the 40%

injection case produced pressure oscillations, which propagated all the way up to the

inlet capture.

• The mean levels of static pressure downstream of the throat did not differ much for both the 20% and the 40% case, except for the 90 Phase injection configuration. A

small drop in pressure could be observed in the first three static taps during injection,

for the 40% injection case.

• The stagnation pressure at the exit increased during injection for the 20% case for allthe injection configurations independent of frequency. No specific trend was

observed for the 40% injection case.

• The mean stagnation pressure recovery at the exit is 0.3. The static pressure rise in the

inlet is about 15. This low-pressure recovery is a result of both shock system lossesand presence of large separation zones in the inlet. The inlet was operated at a

backpressure ratio of 0.2.

• The pressure oscillations downstream of the throat correlated well with the

backpressure excitation frequency.

• For a given injection mass flow and an injection configuration, lower backpressureexcitation frequency produced larger pressure oscillations while the higher

backpressure excitation frequency produced higher exit stagnation pressures.

• The schlieren and the oil flow visualization images confirmed these observations.



APPENDIX ADATA ACQUISITION PROGRAM

LabVIEW programs were used to control the Wind Tunnel and the backpressure

excitation mechanism. This section describes the action of these programs in a flowchart

and later presents the front panels and block diagrams for these programs.

Start

Main

Stop

Continue

ConfigureRegister Calibration

data, channel info., etc

Channel info Acquire Data

Stop

Process DataCalibration const.

57



58

Global Data

Display

Stop?yes no

Po set point

Tunnel?no yes

Tunnel control

Inj. Control

Main

Save

Data?

File path

no yes

Stop Tunnel

yes

no Injection?

Save Data

Figure A-1. Flowchart showing the data acquisition and experimental automation.26

The six primary modules that are triggered manually are Main.vi, Display.vi,

Acquire and Save.vi, Valve control.vi, Telnet to Freedom.vi, AOcontrol.vi and Injseq.vi.

Two computers are used for acquiring pressure data. One of them (Kronos) runs the



59

Main.vi which further loads and runs the other five VI’s (modules) listed above. The

other computer (Freedom) runs the pressure scanner.vi, which handles the PSI9010

scanner pressure data. The sub-VI’s are presented in the order at which they are called.

Also, empty cases and cases where the data is passed through unchanged are not

included. The front panels and block diagrams are scaled to fit the page. The scaling is

different for each VI shown.



60

Main.vi: Opens up and runs the other VI’s on Kronos

Front panel

Block Diagram

Startup.vi



61



62



63

WriteNetVar.vi



64

Shutdown.vi

Startup.vi

Front Panel

Block Diagram

WriteNetVar.vi

Front Panel



65

Block Diagram

Shutdown.vi

Front Panel

Block Diagram



66

Display.vi: The core user interface VI with controls for the tunnel, injection

mechanism and data saving. This VI, simultaneously acquires and plots

the High speed pressure data.

Front Panel

Block Diagram



67

Msg2

Freed

Zer

Word.vi

Format

string .vi



68

Zero.vi: Resets all read pressures to atmospheric pressure on all the pressure

transducers including the pressure scanner (by sending a signal to

Freedom).

Front Panel

Block Diagram



69

Msg2Freedom.vi

Front Panel

Block Diagram

Format string.vi

Front Panel



70

Block Diagram

Word.vi: Writes log file when update log is closed on display panel.

Front Panel



71

Block Diagram



72



73

Acquire and Save: Reads blocks of 250 high-speed data rows and saves to prescribed

file.

Front panel



74

Block Diagram

Process Data.vi



75

Process Data.vi: Applies calibration to read Pressure transducer data to convert

them to psi.

Front Panel



76

Block Diagram

Valve control.vi: Controls the tunnel valve.

Front Panel

Block Diagram



77



78



79



80

Telnet to Freedom.vi: Handles Telnet communication between Kronos and

Freedom.

Front Panel

Block Diagram



81

Msg2Freedom.vi



82

Injseq.vi: Controls the Injection mechanism by actuating the injection solenoids

accordingly.

Block Diagram



83



84

AO Control.vi: Sends the Analog output (voltage) to the Relays as prescribed by

the Injseq.vi.

Front Panel



85

Block Diagram

Droplet.vi: Used for capturing schlieren images.

Front Panel

Block Diagram



86

Pressure Scanner.vi This program reads serial data from PSI9010 scanner on Freedom.



87

Block Diagram

Read Mach 4

WT PSI9010.vi



88



89



90

Read Mach 4 WT PSI 9010.vi

Front Panel

Block Diagram



91



92

Global Controls.vi

Front Panel



APPENDIX B

MATLAB PROGRAM FOR DATA REDUCTION

A MATLAB program was used to compile the pressure data obtained both from

the scanner and the High Speed Transducers (Omega). The program performs the

following operations:

1. The pressures are normalized with respect to the freestream stagnation pressure.

2. Mean and rms values of the normalized pressures are calculated for the time intervalsspecified by the user.

3. Makes the plots of wall mean static pressure and the fluctuation of static pressure,defined as the difference between the maximum and minimum pressures attained, to

the average pressure during injection, with X/L. (normalized axial coordinate

measured from the leading edge of the inlet), with the error bars.

4. Makes the plot of ordinate Y*-the non-dimensional distance of the location of thestagnation probe from the ramp, with the normalized mean stagnation pressure at the

exit, with the error bars

5. Makes the pressure time trace for all the wall static pressures measured in the inlet.

6. Plots are produced based on the transducer assignment provided by the user.

MATLAB Code

%M3_5compile.m

%reads and compiles pressure scanner and Kronos dataflnhs='F:/Raw data/11-13-02p'; %high-speed data file

dsc='//Freedom/PDE Inlet/Scanner data'; %scanner data directoryrunn=flnhs(end-8:end);

hssf=1000; %sampling frequency, high-speed data

bar=0.01; %bar length for std barsn=41; %high speed data points to calculate average over when using with scanner data

curr=cd;

%cd('curr');

% cd('C:\');

d=dir([dsc '/*' flnhs(end-8:end)]); %find matching scanner file

93



94

skipt=0; %skip no transducers in hs data - plot them all

%%Also change statv and strutv below to assign transducers to correct taps.

%

if prod(runn(1:8)=='03-20-02')|prod(runn(1:8)=='04-08-02')|prod(runn(1:8)=='04-11-02'),

mode=17;elseif prod(runn(1:8)=='04-26-02')|prod(runn(1:8)=='04-29-02')|prod(runn(1:8)=='05-20-

02')|prod(runn(1:8)=='05-21-02')...

|prod(runn(1:8)=='06-10-02')|prod(runn(1:8)=='06-13-02')|prod(runn(1:8)=='06-14-02')|prod(runn(1:8)=='06-19-02')...

|prod(runn(1:8)=='06-20-02')|prod(runn(1:8)=='06-21-02')|prod(runn(1:8)=='06-24-

02')|prod(runn(1:8)=='07-02-02')...|prod(runn(1:8)=='07-05-02')|prod(runn(1:8)=='07-15-02')|prod(runn(1:8)=='07-16-

02')|prod(runn(1:8)=='07-17-02')...


02')|prod(runn(1:8)=='09-12-02')...




02')|prod(runn(1:8)=='10-19-02')...|prod(runn(1:8)=='10-20-02')|prod(runn(1:8)=='10-28-02')|prod(runn(1:8)=='10-31-

02')|prod(runn(1:8)=='11-01-02')...

|prod(runn(1:8)=='11-09-02')|prod(runn(1:8)=='11-10-02')|prod(runn(1:8)=='11-

13-02'),

mode=18;

else

mode=99;

end;

switch modecase 17,

sc1=5;

sc2=10;xv=([0.7 1 1.4 1.8 2.2 2.65 3.1 3.1 3.6 3.6])/5.1797;

rpmcol=12;

stagcol=6;

skipt=4; %%skip first 4 transducers in hs file - scxi datacase 18, %Mach 3.5 inlet

sc1=5; % vac line connected to sc 5 06-20-02

sc2=12;%xv=([1.2 1.7 2.1 2.5 2.9 3.1 3.5 3.9 4.3 4.7 5.1 3.9 4.3 4.7 5.1])/5.3041;%added

locations for cowl static taps



95

xv=([1.2 1.7 2.1 2.5 2.9 3.1 3.5 3.9 4.3 4.7 5.1])/5.3041;

yv=[0.145 0.5 0.855]; %stag rake locations from the ramprpmcol=9;

stagcol=3;

skipt=0;

otherwise,

disp('Need parameters! Add in program for this case.'); break;

end;

if length(d)>1,disp('WARNING! More than one matching scanner file found!');

end;

flnsc=[dsc '/' d(1).name]; %file name of scanner file with search path

tsc=str2num(d.name(1:end-10)); %time stamp obtained from scanner file name

hs=load(flnhs);

sc=load(flnsc);[hsrows,hscols]=size(hs);

%scanner format: t, dt, selected ports (sc1-sc2)

%subtracting scanner start time from all time stamps in scanner data

sc(:,1)=sc(:,1)-sc(1,1);

sc(1,2)=sc(2,1)-sc(1,1);

stamp=find(hs(:,1)>0); %row numbers of rows in high-speed data carrying time stamp

(first in each batch)

ths=hs(stamp,1);

if length(tsc)==0, %for scanner files without a time stamp, use start of high-speed datatsc=ths(1);

end;

figure(1);clf;

% plot(sc(:,1)/1000,sc(:,3:end-1));

% hold on;% ha=plot((hs(stamp,1)-tsc)/1000,hs(stamp,2:end-1));

% %ha=plot((0:(length(hs(:,1))-1))/1E3,hs(:,2:end-1));

% for i=1:length(ha),

% set(ha(i),'LineWidth',2);% end;

x=(0:1:length(hs(:,1))-1)/1000;

plot(x,hs(:,2:end-1))grid on;

xlabel('t (s)');



96

ylabel('p (psi)');

title([flnhs(end-8:end)]);% legend([num2str(1:11)']);

sc(:,1)=cumsum(sc(:,2)); %replacing time stamps on scanner data with higher-precision

values

hst=(0:hsrows-1)/hssf;dt=hs(1,1)-tsc; %time difference - start of high-speed data minus start of scanner data

switch runn, %manually set offset time between scanner and high-speed data

case '05-20-02c',dt=dt+840;

case '05-20-02c',

dt=dt+454;case '05-21-02c',

dt=dt+503;

case '06-10-02a',

dt=dt+1234;

case '06-10-02b',dt=dt+1462;

case '06-13-02a',dt=dt+1306;

case '06-14-02d',

dt=dt+1260;case '06-14-02e',

dt=dt+940;

case '06-20-02d',

dt=dt+1172;case '06-21-02a',

dt=dt+1300;

case '06-21-02i',

dt=dt+1280;

case '06-24-02d',dt=dt+1201;

case '06-24-02c',

dt=dt+1325;case '06-24-02e',

dt=dt+1478;

case '06-24-02h',dt=dt+1300;

case '06-24-02i',

dt=dt+1201;

case '07-02-02d',dt=dt+1323;

case '07-05-02a',

dt=dt+785;case '07-05-02b',

dt=dt+1282;



97

case '07-15-02a',

dt=dt+1170;case '07-15-02b',

dt=dt+1328;

case '07-16-02b',

dt=dt+1587;case '07-16-02a',

dt=dt+1230;

case '07-17-02a',dt=dt+1380;

case '08-27-02a',

dt=dt+1260;case '08-28-02a',

dt=dt+1538;

case '09-08-02a',

dt=dt+246;

case '09-08-02b',dt=dt+1246+118;

case '09-12-02a',dt=dt+1297;

case '09-12-02b',

dt=dt+1575;case '09-16-02b',

dt=dt+1486;

case '09-16-02c',

dt=dt+1293;case '09-16-02d',

dt=dt+1198;

case '09-20-02a',

dt=dt+1020;

case '09-22-02a',dt=dt+1220;

case '09-22-02b',

dt=dt+1298;case '09-22-02c',

dt=dt+1268;

case '09-23-02a',dt=dt+1018;

case '09-24-02a',

dt=dt+1098;

case '09-24-02b',dt=dt+1476;

case '09-25-02a',

dt=dt+1286;case '09-25-02c',

dt=dt+1346;



98

case '09-27-02a',

dt=dt+1346;case '09-27-02c',

dt=dt+1346+147;

case '10-03-02a',

dt=dt+1303;case '10-05-02a',

dt=dt+1473;

case '10-05-02d',dt=dt+1263;

case '10-05-02e',

dt=dt+1263;case '10-05-02f',

dt=dt+1343;

case '10-05-02g',

dt=dt+1343;

case '10-05-02h',dt=dt+1343;

case '10-05-02k',dt=dt+1365;

case '10-13-02a',

dt=dt+1400;case '10-13-02b',

dt=dt+1345;

case '10-15-02i',

dt=dt+1245;case '10-15-02n',

dt=dt+1473;

case '10-19-02b',

dt=dt+1123;

case '10-19-02m',dt=dt+1203;

case '10-19-02p',

dt=dt+1736;case '10-19-02q',

dt=dt+1219;

case '10-19-02r',dt=dt+1309;

case '10-19-02s',

dt=dt+1197;

case '10-20-02c',dt=dt+1107;

case '10-20-02d',

dt=dt+1294;case '10-20-02g',

dt=dt+1219;



99

case '10-20-02i',

dt=dt+1337;case '10-28-02i',%[test e=1227,test f=1314,test g=1184,test h=1179,test i=1299]

dt=dt+1299;

case '10-31-02b',%[test b=1314 test c=1314,test f=1378,h=1137,a=1136]

dt=dt+1314;case '11-09-02n',%[a=1272 b=1197 i=1292 j=1318

dt=dt+1302;

case '11-10-02i',%[a=1302 j=1352 i=1268 d=1440 e=1476 f,h,i=1280 j=1354 k=1267m=1548 n=1256]

dt=dt+1280; %[o=1386 p=1277]

case '11-13-02p',%[a=1420 c=1204 d=1263 e=1342 g=1186 h=1524 i=1147 j=1418k=1249 l=1302 m=1500]

dt=dt+1545; %[n=1215 p=1545]

end;

maxdev=max((stamp-1)/hssf-(hs(stamp,1)-hs(1,1))/1000);disp(['Maximum time deviation in high-speed data ' num2str(maxdev) ' s']);

%build normalized highspeed matrix, keep rpm unchanged

%note that hsn lacks first column in hs (time stamps)

stag=hs(:,stagcol); %extracting high-speed data on stagnation pressures%hsn=hs(:,2:end); %not normalize (for plotting abs pressures)

hsn=hs(:,2:end)./(hs(:,stagcol)*ones(size(hs(1,2:end)))); %normalize

hsn(:,stagcol-1)=stag; %restore stagnation pressurehsn(:,rpmcol-1)=hsn(:,rpmcol-1).*stag; %restore rpm

%building a matrix of high-speed data with scanner sampling frequency

hs1=[];hsn1=[];

hsn1q=[];

n1=[];for i=1:length(sc(:,1));

p1=find(abs(hst-(sc(i,1)+dt)/1000)<(n-1)/2/hssf); %find corresponding high-speed data

if (length(p1)<2), p1=[];

hs1=[hs1; NaN*ones(size(hs(1,:)))];

hsn1=[hsn1; NaN*ones(size(hsn(1,:)))];

hsn1q=[hsn1q; NaN*ones(size(hsn(1,:)))];else

hs1=[hs1; mean(hs(p1,:))];

hsn1=[hsn1; mean(hsn(p1,:))];hsn1q=[hsn1q; sum(hsn(p1,:).^2)]; %store quadratic sums too for rms calculation

later



100

end;

n1=[n1; length(p1)]; %no of samples in hsdata converted into single sc data pointend;

%normalize scanner data with stagnation pressure

scn=sc(:,3:end)./(hs1(:,stagcol)*ones(size(sc(1,3:end))));%scn=sc(:,3:end); % for plotting only pressures

figure(2);

clf;ha=plot(sc(:,1)/1000,[hsn1(:,skipt+1) hsn1(:,skipt+3:end-1) scn(:,1:end-1)]);

for i=1:length(hsn1(1,skipt+1:end-2)),

set(ha(i),'LineWidth',2);end;

grid on;

ax=axis;

%axis([0 ax(2) 0 1]);

xlabel('t (s)');ylabel('p/p_0');

title([flnhs(end-8:end), ' - thick hs, thin sc']);% legend([num2str(1:11)']);

figure(24);clf;

plot(sc(:,1)/1000,scn(:,6));

hold on;

sync=dt; %here is where the HST data is in sync with scanner HST1=hsn(sync:end,:);x=(0:length(HST1(:,1))-1)/1000;

plot(x,HST1(:,[1 5 7]));

pstag=[]; pstagrms=[];

pstat=[]; % tap location and scnm

pstatrms=[]; % tap location and scnrms pressure=[]; % rearranging the mean pressures for diff condns in the same run for

subplots

time=[];

% extracting the pressures and saving them in text delimited files

for j=1:3,

switch jcase 1,

%disp('vac sols open');

disp('without injection');case 2,

% %disp('vac sols closed');



101

disp('injection');

case 3,disp('hinjection');

end;

%select excerpt to analyzet1=input( ' Start time ');

t2=input( ' Stop time ');

running=find(sc(:,1)/1000>t1&sc(:,1)/1000<t2);

%calculate mean and rms for normalized values during this time span

scnm=mean(scn(running,:));scnrms=std(scn(running,:),1);

hsn1m=mean(hsn1(running,:));

hsn1rms=sqrt((sum(n1(running))-1)/sum(n1(running)))*sqrt(1/(sum(n1(running))-

1)*(sum(hsn1q(running,:))-(n1(running)'*hsn1(running,:)).^2/sum(n1(running))));

% % make plots for the 3 cases

% HST=hs1(running,2:end-1);% scan=scn.*(hs1(:,stagcol)*ones(size(sc(1,3:end))));

% scan=[sc(running,1)/1000 scan(running,:)];

% press=[scan(:,1) HST(:,1) scan(:,2:end) HST(:,[5 7]) HST(:,[2 3 4 6])];% eval(['save ' runn num2str(j) '.txt press -ascii -tabs']); %saves the pressures in as a

text file in the current dir

%make plots for the cases press=[hsn1(running,1) scn(running,[1:8]) hsn1(running,5) hsn1(running,7)];taps=[1 2 3 4 5 6 7 8 9 10 11];

%making plot of stag rake pressures

stgrake=[scn(running,[9:11])];figure(j+10);

plot(sc(running,1)/1000,stgrake);

axis([t1 t2 0 0.5]);xlabel('t(s)');

ylabel('Po / Po1');

title([flnhs(end-8:end), ' - stagrake']);%

%make stagerred plots for static press vs time in the interval [t1 t2]

figure(7);for k=1:6,

if (j==1),

l=2*k-1;else

l=2*k;



102

end;

subplot(6,2,l);

if (k==1),

T1=t1*1000;T2=t2*1000;

ch=[1 2 3 5 7];

h=plot(t1:0.001:t2,HST1(T1:T2,ch(k)),'k-');set(h,'linewidth',1.5);

end;

if (k>1),h=plot(sc(running,1)/1000, press(:,k),'k-');

set(h,'linewidth',1.5);

end;

if (l==(2*k-1)),

ha=ylabel('p/p_0');set(ha,'Fontsize',24,'Fontweight','bold');

set(get(gca,'YLabel'),'position',[(t1-0.2) 0.11 0]);set(gca,'yticklabel',{'0.04';'';'0.12 ';'';'0.20'});

else

set(gca,'yticklabel',[]);end;

set(gca,'ytick',[0.04:0.04:0.2]);

set(gca,'linewidth',1.5,'ticklength',[0.02 0.035]);

%title(['static tap' num2str(k)]);axis([t1 t2 0.04 0.20]);ax=axis;

set(gca,'xtick',[t1:0.2:t2]);

set(gca,'xticklabel',[]);

ha=text(0.7*ax(2)+0.3*ax(1),0.9*ax(3)+0.1*ax(4),['tap ' num2str(taps(k))]);set(ha,'Fontsize',20,'Fontweight','bold');

set(gca,'Fontsize',20,'Fontweight','bold');

if (l==1),hb=text((t1+(t2-t1)*0.1),0.24,'Without Injection');

set(hb,'Fontsize',24,'Fontweight','bold');

elseif (l==2),hc=text((t1+(t2-t1)*0.18),0.24,'With Injection');

set(hc,'Fontsize',24,'Fontweight','bold');

end;

if (l==11)|(l==12),

set(gca,'xticklabel',[t1:0.2:t2]);ha=xlabel('t (s)');

set(ha,'Fontsize',20,'Fontweight','bold');



103

end;

end;

figure(8);

for k=1:5,if (j==1),

l=2*k-1;

elsel=2*k;

end;

subplot(5,2,l);

if (k<4),

h=plot(sc(running,1)/1000, press(:,k+6),'k-');

set(h,'linewidth',1.5);

end;if (k==4|k==5),

T1=t1*1000;T2=t2*1000;

ch=[1 2 3 5 7];

h=plot(t1:0.001:t2,HST1(T1:T2,ch(k)),'k-');set(h,'linewidth',1.5);

end;

if (l==(2*k-1)),

ha=ylabel('p/p_0');set(ha,'Fontsize',24,'Fontweight','bold');set(get(gca,'YLabel'),'position',[(t1-0.2) 0.11 0]);

set(gca,'yticklabel',{'0.04';'';'0.12 ';'';'0.20'});

else

set(gca,'yticklabel',[]);end;

set(gca,'ytick',[0.04:0.04:0.20]);

set(gca,'linewidth',1.5,'ticklength',[0.02 0.035]);%title(['static tap' num2str(k)]);

axis([t1 t2 0.04 0.20]);

ax=axis;set(gca,'xtick',[t1:0.2:t2]);

set(gca,'xticklabel',[]);

ha=text(0.7*ax(2)+0.3*ax(1),0.9*ax(3)+0.1*ax(4),['tap ' num2str(6+k)]);

set(ha,'Fontsize',20,'Fontweight','bold');set(gca,'Fontsize',20,'Fontweight','bold');

if (l==1),hc=text((t1+(t2-t1)*0.1),0.24,'Without Injection');

set(hc,'Fontsize',24,'Fontweight','bold');



104

elseif(l==2),

hd=text((t1+(t2-t1)*0.18),0.24,'With Injection');set(hd,'Fontsize',24,'Fontweight','bold');

end;

if (l==9)|(l==10),

set(gca,'xticklabel',[t1:0.2:t2]);ha=xlabel('t (s)');

set(ha,'Fontsize',20,'Fontweight','bold');

end;

end;

disp('Average pressure ratios, p/p0');

disp(['scanner: ' num2str(mean(scn(running,:)))]);

disp(['remaining: ' num2str(mean(hsn1(running,:)))]);

for i=sc1:sc2,

disp(['Scanner port ' num2str(i) ': ' num2str(scnm(i-sc1+1)) ' rms: 'num2str(scnrms(i-sc1+1))]);

end;

switch mode

case {1,2,14,15,16,18} %No SCXI transducers during May 2001 and Nov 2001- tests

%note that stagcol now points to static pressure column after removal of first

columndisp(['Tunnel static: ' num2str(hsn1m(stagcol)) 'p0 rms: ' num2str(hsn1rms(stagcol))

' p0']);

disp(['->Mach number: ' num2str(sqrt(5*(hsn1m(stagcol)^(-2/7)-1)))]);

for i=0:6,disp(['Omega ' num2str(i) ': ' num2str(hsn1m(i+1)) ' rms: '

num2str(hsn1rms(i+1))]);

end;

otherwise %with SCXI transducers

for i=1:4,disp(['SCXI ' num2str(i) ': ' num2str(hsn1m(i)) ' rms: ' num2str(hsn1rms(i))]);

end;

%note: stagcol now points to static pressure since one col has been chopped off!

disp(['Tunnel static: ' num2str(hsn1m(stagcol)) ' rms: ' num2str(hsn1rms(stagcol))]);disp(['->Mach number: ' num2str(sqrt(5*(hsn1m(stagcol)^(-2/7)-1)))]);

for i=1:4,disp(['Omega ' num2str(i) ': ' num2str(hsn1m(i+6)) ' rms: '

num2str(hsn1rms(i+6))]);



105

end;

end;

% disp(['RPM: ' num2str(hsn1m(rpmcol-1)) ' rms: ' num2str(hsn1rms(rpmcol-1))]);

% disp(['->f: ' num2str(hsn1m(rpmcol-1)/30) ' rms: ' num2str(hsn1rms(rpmcol-1)/30)]);

%build vectors for plots

switch mode

case 17, %2D inlet with rotating cylinder switch runn,

case '03-20-02a', %HST on static 1-5

statv=[hsn1m([1 4 5 6 7]) scnm([1 4 5])];statvrms=[hsn1rms([1 4 5 6 7]) scnrms([1 4 5])];

case '03-20-02b', %HST on static 6-10

statv=[scnm([1 2 3]) hsn1m([1 4 5 6 7])];

statvrms=[scnrms([1 2 3]) hsn1rms([1 4 5 6 7]) ];

case '04-08-02a', %HST on static 1,2,7,8statv=[hsn1m([7 8]) scnm([1:4]) hsn1m([9 10]) scnm([5 6])];

statvrms=[hsn1rms([7 8]) scnrms([1:4]) hsn1rms([9 10]) scnrms([5 6])];case '04-08-02b', %HST on static 3,4,7,8

statv=[scnm([1 2]) hsn1m([7 8]) scnm([3 4]) hsn1m([9 10]) scnm([5 6])];

statvrms=[scnrms([1 2]) hsn1rms([7 8]) scnrms([3 4]) hsn1rms([9 10]) scnrms([56])];

case '04-08-02c', %HST on static 5,6,7,8

statv=[scnm(1:4) hsn1m([7 8]) hsn1m([9 10]) scnm([5 6])];

statvrms=[scnrms(1:4) hsn1rms([7 8]) hsn1rms([9 10]) scnrms([5 6])];case '04-08-02d', %HST on static 7,8,9,10

statv=[scnm(1:6) hsn1m([7 9 8 10])];

statvrms=[scnrms(1:6) hsn1rms([7 9 8 10])];

case {'04-11-02e','04-11-02d'} %HST on static 7,8,9,10

statv=[scnm(1:6) hsn1m([7 8 9 10])];statvrms=[scnrms(1:6) hsn1rms([7 8 9 10])];

end;

case 18,% Mach 3.5 inlet with fluidic injectionswitch runn,

case '04-26-02f', %HST on static 1,2,3,10,11

statv=[hsn1m([1 4 5]) scnm(1:6) hsn1m([6 7])];statvrms=[hsn1rms([1 4 5]) scnrms(1:6) hsn1rms([6 7])];

case '04-29-02b', %HST on static 1,2,3,10,11

statv=[hsn1m([1 4 5]) scnm(1:6) hsn1m([6 7])];

statvrms=[hsn1rms([1 4 5]) scnrms(1:6) hsn1rms([6 7])];case '04-29-02c', %HST on static 4-8

statv=[scnm(1:3) hsn1m([1 4 5 6 7]) scnm(4:6)];

statvrms=[scnrms(1:3) hsn1rms([1 4 5 6 7]) scnrms(4:6)];case '05-20-02a', %HST on static 1,2,3,10,11,no extra block

statv=[hsn1m([1 4 5]) scnm(1:6) hsn1m([6 7])];



106

statvrms=[hsn1rms([1 4 5]) scnrms(1:6) hsn1rms([6 7])];

case '05-20-02b', %HST on static 1,2,3,10,11,extra max blockagestatv=[hsn1m([1 4 5]) scnm(1:6) hsn1m([6 7])];

statvrms=[hsn1rms([1 4 5]) scnrms(1:6) hsn1rms([6 7])];

case '05-20-02c', %HST on static 1,2,3,10,11,no extra block


case '05-21-02c', %HST on static 1,2,3,10,11,no extra blockage


case '06-10-02a', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra

blockagestatv=[hsn1m(1) scnm(1:8) hsn1m([5 7])];

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];

case '06-10-02b', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra

blockage

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; %some taps loststatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];

case '06-13-02a', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra blockage

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])];

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];case '06-13-02b', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra

blockage

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])];

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];case '06-14-02e', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra

blockage

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % shorter sting


case '06-19-02k', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra blockage

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; %no TFE tubes,no SS tubes at the

back statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];

case '06-20-02d', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra

blockagestatv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180

statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];% vac line on scnm(1)

case '06-21-02a', %HST on static 1,10,11,U/D stream of inj.solenoid,no extra

blockagestatv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180, no W/T run..


case '06-21-02b', %HST on static 1,U/D stream of inj.solenoid,no extra blockagestatv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,no W/T run




107

case '06-21-02c', %HST on static 1,U/D stream of inj.solenoid,no extra blockage

statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,no W/T runstatvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];% vac line on scnm(1)

case '06-21-02i', %HST on static 1,U/D stream of inj.solenoid,no extra blockage

statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,2 inj sols coupled

statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];% vac line on scnm(1)case '06-24-02c', %HST on static 1,U/D stream of inj.solenoid,no extra blockage

statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,90 phase

statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];%case '06-24-02d', %HST on static 1,U/D stream of inj.solenoid,no extra blockage


statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];%case '06-24-02e', %HST on static 1,U/D stream of inj.solenoid,no extra blockage


statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];%

case '06-24-02h', %HST on static 1,U/D stream of inj.solenoid,no extra blockage

statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180, 90 phase offsetstatvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];%

case '06-24-02i', %HST on static 1,U/D stream of inj.solenoid,no extra blockagestatv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,90 phase offset


case '07-02-02d', %HST on static 1,no inj,U/D stream of inj.solenoid,50% extra blockage

statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180


case '07-05-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,20% extra blockage

statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180

statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])]; %90 phase offset

case '07-05-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,20% extra

blockagestatv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180

statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])]; % 90 phase offset

case '07-15-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,20% blockagestatv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,90 phase offset


case '07-15-02b', %HST on static 1,no inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180


case '07-16-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];

case '07-16-02b', %HST on static 1,no inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,tripstatvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];

case '07-17-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,



108

statv=[hsn1m(1) scnm(2:9) hsn1m([5 7])]; % rotated by 180,trip

statvrms=[hsn1rms(1) scnrms(2:9) hsn1rms([5 7])];case '08-27-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,bleed


case '08-28-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,bleed


case '09-08-02b', %HST on static 1,no inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,bleed


case '09-12-02a', %HST on static 1,no inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,bleed


case '09-12-02b', %HST on static 1,no inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,no bleed

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];case '09-16-02b', %HST on static 1, inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%90 phase offset

case '09-16-02c', %HST on static 1, inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180, bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% Symm coup

case '09-16-02d', %HST on static 1, inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180, bleed

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% Antisymmcase '09-20-02a', %HST on static 1, inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180, bleed

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%No inj

case '09-22-02a', %HST on static 1, inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,No bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%Only Ramp

case '09-22-02b', %HST on static 1, inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,No bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%Only Ramp


statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%Only Ramp


statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,No bleed

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%Only Rampcase '09-24-02a', %HST on static 1, inj,U/D stream of inj.solenoid,


statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% No injcase '09-24-02b', %HST on static 1, inj,U/D stream of inj.solenoid,




109

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% No inj,stag tubes

case '09-25-02a', %HST on static 1, inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% No inj,stat tubes


statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% No inj,stag tubes


statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stat tubes


statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stag tubes


statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stat tubes

case '10-05-02a', %HST on static 1, inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,symm

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stat tubescase '10-05-02d', %HST on static 1, inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,symm

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stag tubescase '10-05-02e', %HST on static 1, inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,Anti-symm

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stag tubes

case '10-05-02f', %HST on static 1, inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,Anti-symmstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stat tubes

case '10-05-02g', %HST on static 1, inj,U/D stream of inj.solenoid,


statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stat tubescase '10-05-02h', %HST on static 1, inj,U/D stream of inj.solenoid,


statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stag tubescase '10-05-02k', %HST on static 1, inj,U/D stream of inj.solenoid,


statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];% inj,stag tubescase '10-13-02a', %HST on static 1, inj,U/D stream of inj.solenoid,

statv=[scnm(1) hsn1m([1 5 7]) scnm(2:8)]; % rotated by 180,

statvrms=[scnrms(1) hsn1rms([1 5 7]) scnrms(2:8)];%

case '10-13-02b', %HST on static 1, inj,U/D stream of inj.solenoid,statv=[scnm(1) hsn1m([1 5 7]) scnm(2:8)]; % rotated by 180,

statvrms=[scnrms(1) hsn1rms([1 5 7]) scnrms(2:8)];%

case '10-15-02n', %HST on static 1, inj,U/D stream of inj.solenoid,statv=[scnm(1:4) hsn1m(1) scnm(5:7) hsn1m([5 7]) scnm(8)]; % rotated by 180,

statvrms=[scnrms(1:4) hsn1rms(1) scnrms(5:7) hsn1rms([5 7]) scnrms(8)];%



110

case '10-15-02i', %HST on static 1, inj,U/D stream of inj.solenoid,

statv=[scnm(1:4) hsn1m(1) scnm(5:7) hsn1m([5 7]) scnm(8)]; % rotated by 180,statvrms=[scnrms(1:4) hsn1rms(1) scnrms(5:7) hsn1rms([5 7]) scnrms(8)];%

case '10-19-02b', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%90case '10-19-02m', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,


statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%AS-2case '10-19-02p', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,


statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%S-2case '10-19-02q', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,


statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%S-1

case '10-19-02r', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%AS-1

case '10-19-02s', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed

statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%AS-3

case '10-20-02c', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed


case '10-20-02d', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,

statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleedstatvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%AS-3

case '10-20-02g', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,


statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];%S-1

case '10-20-02i', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed


case '10-28-02i', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[scnm(1:3) NaN NaN NaN NaN hsn1m(7) scnm(4:5) hsn1m([5 7])

scnm(6:8)]; % rotated by 180,with bleed

statvrms=[scnrms(1:3) NaN NaN NaN NaN hsn1rms(7) scnrms(4:5) hsn1rms([57]) scnrms(6:8)];%90

case '10-31-02b', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,


statvrms=[hsn1rms(1) scnrms(1:8) hsn1rms([5 7])];case '11-09-02a', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,

statv=[scnm(1:6) hsn1m([1 5 7]) scnm(7:8)]; % rotated by 180,with bleed

statvrms=[scnrms(1:6) hsn1rms([1 5 7]) scnrms(7:8)];case '11-09-02n', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,




111


case '11-09-02j', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[scnm(4) scnm(1:3) hsn1m([1 5 7]) scnm(7:8) scnm(5:6)]; % rotated by

180,with bleed

statvrms=[scnrms(4) scnrms(1:3) hsn1rms([1 5 7]) scnrms(7:8) scnrms(5:6)];

case '11-10-02i', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed


case '11-13-02p', %HST on static 1,10,11 inj,U/D stream of inj.solenoid,statv=[hsn1m(1) scnm(1:8) hsn1m([5 7])]; % rotated by 180,with bleed


end;

otherwise

disp('Don`t know how to build strut and static profiles for this run - modify

program!');

break;end;

%building matrices of wall static mean and rms values for tecplot

build1=[xv' (statvrms./statv*100)'];

[x,m]=sort(build1); pstatrms=[pstatrms; 0 0; build1(m(:,1),:)];

build=[xv' statv'];

[y,i]=sort(build); pstat=[pstat; 0 0; build(i(:,1),:)];

%making matrices of rake stag mean and rms for tecplot

stag=[scnm(11) scnm(10) scnm(9)];

stagrms=[scnrms(11) scnrms(10) scnrms(9)];

make=[yv' stag'];

[a,b]=sort(make); pstag=[pstag; 0 0; make(b(:,1),:)];

makes=[yv' stagrms'];[p,r]=sort(makes);

pstagrms=[pstagrms; 0 0; makes(r(:,1),:)];

% if (j==3), %a plot for measure of variation of pressure about the mean value duringinjection

figure(j+6); % make sure that the fluc* columns correspond with that of statv

clf;fluc_peak=[ max(hsn1(running,1)) max(scn(running,1:8)) max(hsn1(running,[5

7]))];



112

fluc_valley=[ min(hsn1(running,1)) min(scn(running,1:8)) min(hsn1(running,[5

7]))];% fluc_peak=[max(scn(running,1:3)) NaN NaN NaN NaN max(hsn1(running,1)

max(scn(running,4:5)) max(hsn1(running,5)) max(scn(running,6:8))

max(hsn1(running,7))];

% fluc_valley=[min(scn(running,1:3)) NaN NaN NaN NaN min(hsn1(running,[15])) min(scn(running,4:6)) min(hsn1(running,7)) min(scn(running,7:8))];

fluctuation=(fluc_peak-fluc_valley);

variation = fluctuation./statv;ma=plot(xv(1:11),variation(1:11),'s-');

var=[xv' variation'];

%hold on;%da=plot(xv(12:15),variation(12:15),'d');

set(ma,'linewidth',1.5);

%set(da,'linewidth',1.5);

ha=xlabel('x / L ');

set(ha,'Fontsize',14);ha=ylabel('(Pp-Pv)/Pav');

set(ha,'Fontsize',14);grid on;

axis([0 1 0 1]) ;

%end;

figure(j+2); %mean wall pressure plots

clf;

ri=plot(xv(1:11),statv(1:11),'s-');hold on;%pa=plot(xv(12:15),statv(12:15),'d');

set(ri,'linewidth',1.5);

%set(pa,'linewidth',1.5);

x1=[xv-5*bar; xv+5*bar; xv; xv; xv-5*bar; xv+5*bar];y1=[statv-statvrms; statv-statvrms; statv-statvrms; statv+statvrms; statv+statvrms;

statv+statvrms];

h=line(x1,y1);set(h,'Color',[0 0 1]);

ha=xlabel('x / L');

set(ha,'Fontsize',14);ha=ylabel('p/p_0');

set(ha,'Fontsize',14);

grid on;

ax=axis;axis([0 1 0 0.25]);

%ha=text(0.7*ax(2)+0.3*ax(1),0.9*ax(3)+0.1*ax(4),['f= '

num2str((round(hsn1m(rpmcol-1)/3)/10)) ' Hz']);%set(ha,'Fontsize',14);

ha=title(['static pressures, run ' runn ', ' num2str(t1) '<t<' num2str(t2) ' s']);



113

set(ha,'Fontsize',14);

set(gca,'Fontsize',14);



APPENDIX C

INLET DRAWINGS

The AutoCAD drawings of the two-dimensional, mixed compression, supersonic

inlet is presented here. The main components of the inlet are as follows:

1. Cowl

2. Ramp, which has the wall static pressure ports and also houses the bleed plenums for boundary layer suction.

3. Exit injection block, which enables air injection into the inlet at the exit.

4. Sideplates, which supports the cowl and ramp in the correct alignment.

5. Sting, which supports the entire inlet assembly in the Wind Tunnel.

All the components, except the sideplates and the sting are made of Aluminum. The

sideplates are made of Plexiglas for optical access and the sting made of carbon heat

treated steel for resisting bending in the high-pressure environment of the Wind Tunnel.

All the dimensions in the drawings that follow are in inches. The CAD drawings are

scaled to fit the page and the scaling is different for each drawing shown. All the angles

shown are measured with respect to the horizontal.

10o

Figure C-1. The cowl.

114



Front View

Side V

Top View

Figure C-2. The inlet ramp.



116

Table C-1. Coordinates of points relative to the leading edge of the ramp that make the

ramp profile

Point X(in) Y(in)

1 0 0

2 0.5 0.05

3 1 0.125

4 1.25 0.168

5 1.5 0.212

6 1.75 0.254

7 1.865 0.276

8 2 0.294

9 2.25 0.325

10 2.5 0.353

11 2.75 0.359

12 3 0.348

13 3.25 0.325

14 3.5 0.295

15 3.75 0.26

16 4 0.223

17 4.25 0.186

18 4.5 0.151

19 4.75 0.121

20 5 0.1

21 5.25 0.087



117

(a)

Front View

Top View

Figure C-3. The sideplates

(b)

Figure C-4. The sting.



Rear View

Sectional Views

Top View

Figure C-5. The exit injection block.



Top View10

o

5o

Front View Sid

Figure C-6. The inlet assembly.



APPENDIX DSCHLIEREN MOVIES

Schlieren was used to visualize the inlet flow field and the images were recorded

on a SONY camcorder. Short movies, capturing the inlet flow field during the injection

phase, were made with the help of MGI Video Wave – 4 software. Table D-1 lists the test

conditions and also gives the order in which they are found later in this section. The

injection configurations with their associated definitions are given in Chapter 2. For the

zoomed in terminal shock movie, the test conditions are S-2 injection configuration, 5 Hz

excitation frequency and 23% mass injection. Similarly for the zoomed in inlet capture

movie, the test conditions are 90 Phase coupling, 5 Hz excitation frequency and 47%

mass injection.

The following can be observed in the movies:

• The terminal normal shock oscillations can be clearly seen during injection. Itsimmediate return to the initial position when the excitation is stopped can be clearly

seen.

• In the zoomed in view of the terminal shock, its structure, being partly normal andterminating as lambda shocks on the cowl and the ramp walls can be observed. The

degree of separation on the ramp and the cowl can be observed.

• The shock-induced separation region translates along with the shock.

• The shock weakening as it moves upstream can be observed clearly in the 90 Phase

configuration movies.

• Higher mass injection case i.e., 40% case producing greater shock displacement and

increased spillage at the inlet capture can be observed.

• In the 10 Hz case, the increase in curvature of the shock can be seen in the maximumdisplacement position. The shock is fixed on the ramp but curves forward.

120



121

Table D-1. List of schlieren movies.

Test Conditions

F=10 Hz ; Minj=20%

S-2 Coupling

AS-2 Coupling

90 Phase Coupling

F=5 Hz ; Minj=20%

AS-2 Coupling

S-2 Coupling

S-1 Coupling

AS-3 Coupling

90 Phase Coupling

F=5 Hz ; Minj=40%

S-1 Coupling

AS-3 Coupling

S-2 Coupling

AS-2 Coupling

90 Phase Coupling

Zoomed in views

Zoomed at Terminal Shock

Zoomed at inlet capture



122

Object D-1.S-2 Coupling, Minj=20.7%, F=10 Hz.

Object D-2. AS-2 Coupling, Minj=20.7%, F=10 Hz.

http://as-2_20_10hz.avi/

http://s-2_20_10hz.avi/





124

Object D-5. S-2 Coupling, Minj=18.5%, F=5 Hz.

Object D-6. S-1 Coupling, Minj=19.5%, F=5 Hz.





125

Object D-7. AS-3 Coupling, Minj=19.5%, F=5 Hz.

Object D-8. 90 Phase Coupling, Minj=23%, F=5 Hz.

http://90_20_5hz.avi/




126

Object D-9. S-1 Coupling, Minj=39%, F=5 Hz.

Object D-10. AS-3 Coupling, Minj=39%, F=5 Hz.





127

Object D-11. S-2 Coupling, Minj=39%, F=5 Hz.

Object D-12. AS-2 Coupling, Minj=39%, F=5 Hz.





128

Object D-13. 90 Phase Coupling, Minj=39%, F=5 Hz.

Object D-14. Zoomed view of terminal shock for the S-2 Coupling, Minj=23%, F=5 Hz

case.

http://zoomsk_s-2_23_5hz.avi/

http://90_40_5hz.avi/



129

Object D-15. Zoomed view at capture for the 90 Phase Coupling, Minj=47%, F=5 Hz

case.

http://zoomcowl_90_47_5hz.avi/



LIST OF REFERENCES

1. Anthony B. Opalski and Sajben Miklos, “Inlet/Compressor System Response to

Short-Duration Acoustic Disturbances,” Journal of Propulsion and Power , Vol. 18,

No. 4, July-August 2002, pp. 922-932.

2. Mullagiri, S., Gustavsson, J.P.R., Segal, C., “Modeling of Air Intake and EngineInteraction in Pulse Detonation Engine Systems,” AIAA Paper 2001-1211,

Proceedings of the ISABE 2001 Conference, Bangalore, India, Sep 2001.

3. Mullagiri, S. and Segal, C., “Oscillating Flows in Inlets of Pulse Detonation

Engines,” AIAA Paper 2001-0669, 39th

AIAA Aerospace Sciences Meeting and

Exhibit , Reno, NV, January 2001.

4. Chen, C.P., Sajben, M. and Kroutil, J.C., “Shock Wave Oscillations in a Transonic

Diffuser Flow,” AIAA Journal , Vol. 17, No. 10, October 1979, pp. 1076-1083.

5. Bogar, T.J., Sajben, M. and Kroutil, J.C., “Characteristic Frequencies of Transonic

Diffuser Flow Oscillations,” AIAA Journal , Vol. 21, No. 9, September 1983, pp.1232-1240.

6. Sajben, M., Bogar, T.J. and Kroutil, J.C., “Forced Oscillation Experiments in

Supercritical Diffuser Flows,” AIAA Journal , Vol. 22, No. 4, April 1984, pp. 465-

474.

7. Bogar, T.J., Sajben, M. and Kroutil, J.C., “Response of a Supersonic Inlet toDownstream Perturbations,” Journal of Propulsion and Power , Vol. 1, No. 2, March-

April 1985, pp. 118-125.

8. Sajben, M., Bogar, T.J. and Kroutil, J.C., “Experimental Study of Flows in a Two-Dimensional Inlet Model,” Journal of Propulsion and Power , Vol. 1, No. 2, March-

April 1985, pp. 109-117.

9. Bogar, T.J., “Structure of Self-Excited Oscillations in Transonic Diffuser Flows,”

AIAA Journal , Vol. 24, No. 1, January 1986, pp. 54-61.

10. Hongprapas Sorarat, Kozak D. Jeffrey, Moses Brooks and Ng F. Wing., “A small

scale Experiment for investigating the stability of a supersonic inlet,” AIAA paper

97-0611, 35th

AIAA Aerospace Sciences Meeting and Exhibit , Reno, NV, January1997.

11. Dailey, C.J., “Supersonic Diffuser Instability,” Journal of the Aeronautical Sciences,Vol. 22, No. 11, November 1955, pp. 733-749.

12. Van Wie, D.M., Kwok, F.T. and Walsh, R.F., “Starting Characteristics of Supersonic

Inlets,” AIAA paper 96-2914, 32nd

Joint Propulsion Conference and Exhibit , BuenaVista, FL, July 1996.

130



131

13. Fernandez Rene and Nenni P. Joseph., “Pulsed Detonation Engine Inlet Experimental

and CFD Results,” NASA TM 2002-211581.

14. Culick, F.E.C. and Rogers, T., “The Response of Normal Shocks in Diffusers,” AIAA Journal , Vol. 21, No. 10, October 1983, pp. 1382-1390.

15. Hsieh, T., Wardlaw Jr., A.B. and Collins, P., “Numerical Investigation of Unsteady

Inlet Flowfields,” AIAA Journal , Vol. 25, No. 1, January 1987, pp. 75-81.

16. Hsieh, T., Bogar, T.J. and Coakley, T.J., “Numerical Simulation and Comparison

with Experiment for Self-Excited Oscillations in a Diffuser Flow,” AIAA Journal ,Vol. 25, No. 7, July 1987, pp. 936-943.

17. Hsieh, T., Wardlaw Jr., A.B. and Coakley, T., “Ramjet Diffuser Flowfield Response

to Large-Amplitude Combustor Pressure Oscillations,” Journal of Propulsion and Power , Vol. 3, No. 5, September-October 1987, pp. 472-477.

18. Biedron, R.T., and Adamson Jr., T.C., “Unsteady Flow in a Supercritical Supersonic

Diffuser,” AIAA Journal , Vol. 26, No. 11, November 1988, pp. 1336-1345.

19. Hsieh Shih-Yang and Yang Vigor, “A Unified Analysis of Unsteady Flow Structuresin a Supersonic Ramjet Engine,” AIAA Paper 97-0396 , 35

th AIAA Aerospace Sciences

Meeting and Exhibit , Reno, NV, January 1997.

20. Pegg, R.J., Couch, B.D. and Hunter, L.G., “Pulse Detonation Engine Air Induction

System Analysis,” AIAA Paper 96-2918 , 32nd

Joint Propulsion Conference, Lake

Buena Vista, FL, July 1996.

21. NASA Glenn Research Center, Cleveland, Ohio, “Pulse Detonation EngineTechnology Project,” URL: http://www.grc.nasa.gov/WWW/AERO/base/pdet.htm,

March 21st

, 2002.

22. Bussing, T. and Pappas, G., “Pulse Detonation Engine Theory and Concepts,”

Developments in High-Speed-Vehicle Propulsion Systems, Progress in Astronauticsand Aeronautics, Vol. 165, 1996.

23. Heiser, W.H. and Pratt, D.J., “Thermodynamic Cycle Analysis of Pulse Detonation

Engines,” Journal of Propulsion and Power , Vol. 18, No. 1, January-February 2002, pp. 68-76.

24. Eidelman, S. and Yang, X, “Analysis of the Pulse Detonation Engine Efficiency,”

AIAA paper 98-3877, July 1998.

25. Bussing, T.R.A., Bratkovich, T.E. and Hinkley, J.B., “Practical Implementation of Pulsed Detonation Engines,” AIAA paper 97-2748, 1997.

26. Sudarshan Mullagiri, “Forced Nonuniform Oscillation of Backpressure on aSupersonic Diffuser,” University of Florida at Gainesville, MS thesis, August 2001.

http://www.grc.nasa.gov/WWW/AERO/base/pdet.htm

http://www.grc.nasa.gov/WWW/AERO/base/pdet.htm



BIOGRAPHICAL SKETCH

Venkata Narasimham Nori was born on March 17, 1979, in India. He grew up in

the city of Hyderabad and completed his schooling from Atomic Energy Central School-

II (AECS-II) in 1994. He finished his high school studies from the Little Flower Junior

College (LFJC) in 1996. Nori graduated from the Indian Institute of Technology, Madras

(IIT-M), in 2001 where he obtained Bachelor of Technology in aerospace engineering.

He pursued graduate studies at the University of Florida from 2001 to 2002 and obtained

a Master of Science degree from the Department of Mechanical and Aerospace

Engineering.

His interests range from soccer to supersonics, from listening to music to absurd

theorizing, from poetry to photography, from star gazing to chasing wild dreams, from

Documents

Venkata Narasimham Nori- Unsteady Flow in a Mixed-Compression Inlet at Mach 3.5