AEROTHERMODYNAMIC TOPOLOGY OPTIMIZATION OF HYPERSONIC RE-ENTRY … · 2018-02-07 · heating, a new concept of the Non-ablative TPS for hypersonic vehicles was first proposed and

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International Journal of Mechanical Engineering and Technology (IJMET)

Volume 9, Issue 1, January 2018, pp. 1114–1123, Article ID: IJMET_09_01_119

Available online at http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=9&IType=1

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication Scopus Indexed

AEROTHERMODYNAMIC TOPOLOGY

OPTIMIZATION OF HYPERSONIC RE-ENTRY

VEHICLE WITH AEROSPIKE BY USING CFD

Harish Panjagala Faculty of Mechanical Engineering,

Koneru Lakshmaiah Educational Foundation,

Vaddeswaram, Guntur, Andhra Pradesh, India

E L N Rohit Madhukar, I Ravi Kiran, V Shashank, Sai Venkata Bharadwaj

UG Scholar, Department of Mechanical Engineering,

Koneru Lakshmaiah Educational Foundation,

Vaddeswaram, Guntur, Andhra Pradesh, India

ABSTRACT

Due to increasing demand of High Speed reentry vehicles for Space activities in

the world, a major issue related to the process of slowing down a body is by the

formation of stronger shocks that leads to extreme heat generated at the nose. The

cost of thermal protection systems generally used to reduce the heat in the reentry

vehicles is very high. So, there is a need of study to reduce aero heating in space

vehicles. In this paper the eventual outcome is to reduce the aero heating, it is

achieved by introducing a spike at frontal region of the nose. In addition, this spike is

also used in avoiding the damage and preserving the structural integrity of vehicle

over elevated temperatures. Further, by changing the geometry of the tip of spike

yielded some better results. Hence, we suggest usage of spike in reentry vehicles is the

most effective and economical over other protection systems.

Key words: Heat generation, Thermal protection, Reentry vehicle, Aero-Heating,

Spike, Structural integrity.

Cite this Article: Harish Panjagala, E L N Rohit Madhukar, I Ravi Kiran, V

Shashank, Sai Venkata Bharadwaj, Aerothermodynamic Topology Optimization of

Hypersonic Re-Entry Vehicle with Aerospike by using CFD, International Journal of

Mechanical Engineering and Technology 9(1), 2018, pp. 1114–1123.

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=9&IType=1

1. INTRODUCTION

Winged flight vehicles are generally designed & manufactured with blunt noses. Co-efficient

of heat & pressure loadings are often more at the vehicle nose, and a large radius at the nose

helps to withstand, distribute, and dissipate these loads. Understanding, analyzing and

predicting high speed flow around blunt bodies thus poses a practical and important

Aerothermodynamic Topology Optimization of Hypersonic Re-Entry Vehicle with Aerospike by

using CFD


engineering problem; faster and better design of new flight vehicles depends on it. Referring

to the role of wind tunnels in fluid dynamical studies, in 1946 von Neumann Said “Indeed, to

a great extent, experimentation in fluid dynamics is carried out under conditions where the

underlying physical principles are not in doubt, where the quantities to be observed are

completely determined by known equations. Thus wind tunnels, for example, are used at

present, at least in part, as computing devices to integrate the PDE's of fluid dynamics.”

F.F.J. Schrijer, F. Scarano & B.W. van Oudheusden [1] was conducted an experiment on

Separation of Boundary Layer and Reattachment on a Blunted Cone-Flare using QIRT.

Transient HT measurements have been carried out on a blunted cone flare model in a short

duration hypersonic facility at Mach 9 using quantitative infrared thermography (QIRT). The

surface temperature was measured using an infrared vision camera and the temperature data

were successfully correlated to heat transfer co-efficient using two distinct reduction

techniques. Z. Jiang, Y. Liu & G. Han [2] was conducted an experiment to achieve effective

wave for reducing the drag under non-zero attack angles and also to avoid from severe aero

heating, a new concept of the Non-ablative TPS for hypersonic vehicles was first proposed

and blunt spike is combined with lateral jets for developing a reconstructing system of shock

at front side of hypersonic vehicles. The spike works as recast of the bow shock at front

portion of a blunt vehicle, the lateral jet works to reduce the aero heating at the tip of spike

and push the shock in conical form away from the blunt body. The experimental visualization

of flow & pressure measurements was conducted in a hypersonic wind tunnel for both the

conceptual demonstration and CFD validation.

D. Dirkx & E. Mooij [3] was investigated the conceptual design of a re-entry vehicle, by

varying the vehicles shape and geometry and evaluated its impact on performance. They

studied the two classes of shape optimization in vehicles, one is capsule and other one is

winged vehicle. By using the local-inclination methods aerodynamic characteristics of those

vehicles were analyzed. Entry trajectories at Mach 3 were calculated by assuming trimmed

conditions. It has also been studied that based on the geometry of the structure there is

significant drop on pressure and temperature of anybody travelling in compressed medium but

at stagnant point at which the structure is changed between slendered nacile and again

compared to a blunt nacile based on the work of P. Harish et al [4]. It has been studied that

there is an important role of temperature in supersonic and hypersonic travel because of

compressible effects and the thermal load reduction methods such as counter flow ejection of

fluid jet of lower temperature as one of the precautionary measure based on the work of Y.Y.

Zeng et al [5]. It was also studied that there is the sudden change of properties in fluid at the

nacile portion of the re-entry vehicle due to operational velocity and a range of shocks such as

bow shock in frontal end of the vehicle. This situation is analyzed with and without spike and

compared with noting of pressure drop in spiked vehicle based on work of C. Nataraj et al [6].

In this work, a blunt reentry vehicle is modelled in Solid works 2016 and analysed in

ANSYS Fluent 17.2. Validation is performed with the obtained CFD results with the

experimental values of F.F.J. Schrijer et al [1] .Next, optimisation is carried out by placing

spikes at the front of the blunt body. Flow analysis is performed using the validated inputs.

The main results of the simulation are discussed and compared with the vehicle without spike.

Harish Panjagala, E L N Rohit Madhukar, I Ravi Kiran, V Shashank, Sai Venkata Bharadwaj


2. MODELING AND ANALYSIS

2.1. Modelling by using Solid Works 2016 Software

A 2D DART model has been drafted in solid works as shown in fig 2.1.1. For the analysis, the

model is imported to ansys fluent solver. DART (Delft Aerospace re-entry test vehicle) is a

re-entry vehicle designed at TU Delft. This model was developed with an intension to collect

aero thermodynamic flight data and tested for its innovative thermal protection systems.

A 3D model of the re-entry vehicle as shown can be created by revolving the drafted 2D

model about a particular axis. However, the re-entry vehicle is an axisymmetric body, the

analysed results for 2D model is therefore sufficient to verify the entire 3D model.

Figure 2.1.1 2D geometry of blunt body

Figure 2.1.2 3D model of blunt body

2.2. Meshing by using Ansys Fluent 17.2

A Domain has been created near the vicinity of the vehicle (with and without spiked) in the

shape of „D‟ as shown in the fig 2.2.1. This 2D domain provides the information regarding the

behavior of air particles (atmosphere) near to the surface of re-entry vehicle.


using CFD


Figure 2.2.1 Mesh model of blunt body

Hybrid meshing is utilized on the model. Most of the space in the domain has unstructured

grid. All triangles method is inserted in meshing. Edge sizing and inflation are incorporated to

create structured grid around the boundary of the (re-entry) vehicle. The structured grid

consists of 5 layers of 1mm thickness each which helps to study the variations in the

properties such as temperature, pressure, Mach no etc. near the boundary. The mesh size

function is guided by curvature and fine mesh is generated.

2.3 Boundary Condition Calculations

After creating and meshing of the Vehicle in ANSYS then we are Exporting the model in to

the ANSYS FLUENT 17.2 for the flow analysis for the flowing references.

At Mach number (M) =9.1

Gamma ( ) = 1.4

Stagnation pressure= in bar

Static temperature=T in Kelvin

Stagnation temperature= in Kelvin

From Alan-pope formula:

(

)

(1)

=

(

)

= 0.002205 bar (calculate and input into fluent)

From Wegener formula p =

+4.114 (T in Rankine) (2)

T =

(3)

T= 49.6763 + 273 k (Static temperature, k)

= T (

(4)

=49.6763(

)

=873.446K (Stagnation temperature, k)



2.4. Flow Analysis using Ansys Fluent 17.2

The results for the Blunt re-entry vehicle are indicated. The temperature values along with

corresponding contours and graphs are shown in figures.

Figure 2.4.1. Temperature Contour of Blunt Body Figure 2.4.2 Temperature Plot of Blunt Body

We observed that the temperature at the nose for the re-entry hypersonic vehicle was 908 k.

3. VALIDATION AND VERIFICATION

The experiment was done at Delft University of Technology, Netherlands. The tunnel was

operated at a free stream of Mach number 9.1. The settling chamber of the wind tunnel is

pressurized at a total pressure P0 ranging between 25 and 75 bars. The fluid (dry air) is heated

to a temperature of 873 K with a temperature controlled electrical heating system

The below figure shows the experimental scleren graph. This graph shows the shock wave

pattern and the fluent generated shock wave pattern for the same experimental input so we are

comparing the both graphs for validation.

Figure 3.1 Comparison of Experimental Result with analytical result


using CFD


Figure 3.2. The heat transfers for the experimental model at different Reynolds number with free

stream M∞ =9.1

3.1. Calculation of Heat Transfer Co-efficient (CH)

The Heat Transfer Rate is given by the relation

(

) (5)

Where the values of ρ (density), c (specific heat) and l (thickness) of the skin are

„ρ‟ density of Stainless Steel = 8000 Kg/m3

„c‟ specific heat of Stainless Steel = 502 J/Kg K

„l‟, thickness of the material = 10 mm

and the co-efficient of heat transfer is calculated by using the equation (2)

( (6)

Where, ρ∞, U∞, and Cp∞ are free-stream density, velocity and specific heat at constant

pressure. To is stagnation temperature of the given run and Tw is wall temperature at a given

instant time.

The below figure shows the graph of experimental as well as fluent generated graph of CH

vs. X/L.

Figure 3.3 Comparison of Experimental Result with Simulation.

From the figure shown in 3.3 we found that deviation between experimental and

Simulation results is less than 5%. Hence, the taken case is validated, in order to reduce cost

and time we are continuing our simulation in ANSYS FLUENT 17.2 itself.

0

2

4

6

8

0 0.5 1 1.5 2

CH x

10

e3

x/l

CH vs X/L

Without spikeCFD

EXPERIMENTAL



4. TOPOLOGY OPTIMIZATION

From the without spike results, we observed that the temperature at the nose is very high, so

that we are concentrating on reducing the Temperature at nose. In order to reduce the nose

temperature, we introduced spike for the same model and for same input and successfully

found that there is reduction in nose temperature compared to without spike one.

Figure 4.1. Blunt Spike Figure 4.2. Slender Spike

By varying the shape and geometry of spikes and its impact on performance is evaluated,

in this study, the shape optimization of two classes of spikes has been studied: A spike with

tip as slender & blunt. On one side, slender spike design reduces the drag but more in

aerodynamic heating. On the other side, blunt spike design produces more drag. But they are

choosable as aero heating is concerned. To avoid stronger shocks and also for reducing the

temperature, spikes are placed at frontal portion of the nose region.

Modeling, Meshing & Flow analysis is carried out as same as the without spike model for

the same inputs. A spike of two designs was introduced at the nose region of hypersonic

winged re-entry vehicle. Blunt spike with entire length 40mm and having blunt radius at tip of

3mm. slender spike of length 40 mm and having slender angle at tip of 17.060.

Figure 4.1. Mesh Model of Blunt Spike Vehicle Figure 4.2. Mesh Model of Slender Spike Vehicle

5. RESULTS AND DISCUSSION

5.1. Blunt Spiked Body

For Blunt, spiked body the following pressure profile and Temperature profile is analyzed.

Figure 5.1.1 Temperature Contour of Blunt Spike Figure 5.1.2 Enlarged View of Temperature profile Body


using CFD


Figure 5.1.2.Temperature Plot of Blunt Spike Body

We observed that the temperature at the nose for the Blunt Spike Re-entry Hypersonic

vehicle was 812 k .The shock wave scattered along the length and decreases the temperature

along physical domain.

5.2. Slender Spiked Body

For slender spiked body Temperature profile is shown below.

Figure 5.2.1. Temperature Contour of Slender Spike Figure 5.2.2. Enlarged View of Temperature Profile Body

Figure 5.2.3 Temperature Plot of Slender Spike



We observed that the temperature at the nose for the slender spiked Re-entry Hypersonic

vehicle was 848k.

Figure 5.3. Comparision of Temperature values of without spike and with spiked (Blunt & Slender)

vehicles

The figure 5.3 shows comparison of temperature values between without spike and with

spiked vehicle that includes both Blunt & Slender Spike respectively. The frontal portion

(nose) of without spiked vehicle is at a higher temperature than that of its other parts.

However, there isn‟t an appreciable decrease of temperature throughout the body. On the

other hand, with spiked vehicles has showed a better response in the reduction of temperature

especially at the nose. Moreover, blunt spike vehicle is much more effective than the slender

one with some small deviations in there followed path.

6. CONCLUSIONS

For many years‟ people are engaged in research to understand the behavior of hypersonic

flow. There are still many challenges encountered to carry out analysis and to design these

vehicles. In this paper we carried out design and optimization for the re-entry vehicle in

hypersonic flight regime at Mach no 9.1.

While analyzing both spiked (Blunt & Slender) hypersonic vehicle, as we notice that by

introducing the Blunt spike there is 13% reduction of heat at the nose and slender spike is

around 7.5 % compared with without spike model. Finally, we conclude that due to spikes

there is a heat reduction at nose. When the slender spiked vehicles are comparatively less with

Blunt spiked vehicles. So, Blunt spikes are comparatively preferable over slender ones

REFERENCES

[1] Schrijer Ferry F.J. and Scarano Fulvio and Bas W. van Oudheusden, Hypersonic

Boundary Layer Separation and Reattachment on a Blunted Cone-Flare using Quantitative

Infrared Thermography, AIAA International Space Planes and Hypersonic Systems and

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[2] Jiang Zonglin and Liu Yunfeng and Han Guilai, A new concept of the Non-ablative

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0

200

400

600

800

1000

-0.04 -0.02 -0.01 0.00 0.02 0.04 0.06 0.08 0.10 0.12

Tem

per

atu

re (

K)

Position (m)

Without spike Blunt spike Slender Spike


using CFD


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AEROTHERMODYNAMIC TOPOLOGY OPTIMIZATION OF HYPERSONIC RE-ENTRY … · 2018-02-07 · heating, a new concept of the Non-ablative TPS for hypersonic vehicles was first proposed and