37_Pulse Detonation Core Engine - Home | · PDF fileEuropean Workshop on New Aero Engine Concepts Munich, 30 June – 1 July 2010 Pulse detonation What pulse detonation is a) The detonation

European Workshop on New Aero Engine ConceptsMunich, 30 June – 1 July 2010

NEWAC is an Integrated Project Co-funded by the European Commission within the Sixth Framework Programme(2002-2006) under Thematic Priority 4 Aeronautics and Space.

08 June 2010 1


Pulse Detonation Core Engine(from WP 2.3: Future Innovative Core Configuration – A. Lundblahd, VOLVO Aero

WP2.3.3: Innovative combustion – F Giuliani, TU Graz )


F. Giuliani, A. Lang, Graz University of Technology, AustriaT. Grönstedt, M. Irannezhad, Chalmers University, Sweden


Contents

• Pulse detonation

• Literature survey – statistics

• Hybrid engine concept



• Intermittent flow analysis

• Conclusions and recommendations


Contents









Pulse detonation

What pulse detonation is

a) The detonation is initiated at the closed end of the tube

b) The detonation propagates towards the open end

c) The detonation diffracts outside as a decaying shock, in meantime a reflected expansion wave propagates back to


meantime a reflected expansion wave propagates back to the closed end, starting the blow-down process

d) At the end of the blowdown process, the tube contains burned products at rest

d) The purging/filling process is triggered by the opening of the valve, sending a shock wave in the burned gases, followed by the air/product surface

e) A slug of air is injected before the reactants for purging

g) The purging air is pushed out of the tube by the reactants

h) The reactants eventually fill the tube completely and the valve is closed


Pulse detonation

IDEA: replace the conventional combustor with a pulse detonation combustor



Pulse detonation

Why ?

– Higher predicted thermal efficiency

– Pressure gain: lower


– Pressure gain: lower compressor PR required at similar thrust for a hybrid PDE concept

– Reduced TSFC at similar thrust

– Potential for reducing and simplifying the engine core


Pulse detonation

Why ?

– Higher predicted thermal efficiency

– Pressure gain: lower

Knowing that :

– Low TRL technology

– Non-conventional fuel so far


– Pressure gain: lower compressor PR required at similar thrust for a hybrid PDE concept

– Reduced TSFC at similar thrust

– Potential for reducing and simplifying the engine core

– Flow intermittency

– Stoichiometry + peak T >> 2000 K -> NOx

– Pressure gain -> need of compressing the cooling air

– Complexity of cycle control

– Noise


Contents









Literature survey - Statistics



Contents









Hybrid engine concept




Reference test case

1200

1400

1600

1800

2000Entropy - Temperature Diagram (Reference)

Tem

pera

ture

[K]

Engine Net Thrust: 122.53 [kN]Equivalence Ratio (φ): 0.33 [-]Thrust Specific Fuel Consumption (TSFC): 13.23 [mg/(N*s)]

p5=32.97 [bar]

p =9.02 [bar]

5

6


0 500 1000 15000

200

400

600

800

1000

1200

Entropy [J/(kg*K)]

Tem

pera

ture

[K]

pamb=1.01 [bar]

p1=1.06 [bar]

p3=2.35 [bar]

p4=34.7 [bar]

p6=9.02 [bar]

p7=3.63 [bar]

p8c=1.94 [bar]

018bp23

4

6

7

8c

p2=1.53 [bar]



Option 1: Same TSFC, „lighter frame“

1200

1400

1600

1800

2000Entropy - Temperature Diagram (PDE - Case 1)

Tem

pera

ture

[K]


Nondimensional heat added (q): 5.07 [-]

pamb=1.01 [bar]p5=27.91 [bar]

p =9.74 [bar]

5


0 500 1000 15000

200

400

600

800

1000

1200

Entropy [J/(kg*K)]

Tem

pera

ture

[K]

Temperature ratio of compression (ψ): 2.36 [-]

Peak Pressure after the Rayleigh Heat Addition: 132.36 [bar]Peak Temperature after the Rayleigh Heat Addition: 2584 [K]Pressure ratio of the PDE: 1.6 [-]

p1=1.06 [bar]

p2=1.53 [bar]p3=2.35 [bar]

p4=17.35 [bar]

p6=9.74 [bar]

p7=3.82 [bar]

p8c=2.07 [bar]

018bp23

4

6

7

8c



Option 2: Lower TSFC, „heavier frame“

1200

1400

1600

1800

2000Entropy - Temperature Diagram (PDE- Case 2)

Tem

pera

ture

[K]


pamb=1.01 [bar]

p5=46.13 [bar]

p6=10.77 [bar]

5

6


0 500 1000 15000

200

400

600

800

1000

Entropy [J/(kg*K)]T

empe

ratu

re [K

]

Nondimensional heat added (q): 4.06 [-]

Temperature ratio of compression (ψ): 2.87 [-]

Peak Pressure after the Rayleigh Heat Addition: 193.42 [bar]Peak Temperature after the Rayleigh Heat Addition: 2421 [K]

Pressure ratio of the PDE: 1.3 [-]p

1=1.06 [bar]

p2=1.53 [bar]

p3=2.35 [bar]

p4=34.7 [bar]

p7=4.11 [bar]

p8c

=2.22 [bar]

018bp23

47

8c



ASSESSMENTS

„Lighter frame“ „Less TSFC“

TSFC same -5,4%

NOx +85,2% +97,1%


Mass -6,5% +12,7%

Length* -10% +1,2%

HPC casing

Injection modules (one per

tube)

40 PDE’s

PDC collector and relaxation chamber

* Provided the assumption of bended tubes is valid


Contents









• G2D Unsteady RANS Solver developed at Chalmers University

• Used for 2D simulation of detonation tubes

Intermittent flow analysis


8. Juni 2010Andreas LANG - TU Graz 18

Time sequence per detonation cycle (here operation at 62.5Hz)



Study @ TU Graz• Focus on the PDC operation as a

function of the ignition sequence• Geometry: from Aarnio et al. 1996,

for validation purpose

Study @ Chalmers• Focus on the interaction of the

intermittent flow on the turbine• Geometry: PDC + guide vanes



• Mixture: air + hydrogen at Phi=1• Split mixture air 50% / buffer air

50% (Phi global = 0.5)• Operation at ambient conditions• 50 Hz cycles

• Mixture : air + kerosene at Phi=1, split 50%-50% (phi global 0.5)

• Inlet conditions P=32 bar, T=850K• 62.5 Hz cycles



Effect of a controlled phase-shift on the outlet conditions of a PDC




Pulse Detonation Combustor - turbine interaction

• Turbine rotor loss modeled after Kacker and Okapuu (1982)


(1982)

• -> 3.85% HPT efficiency loss


Contents









Conclusions

• Design and simulation tools for a hybrid engine concept were developed and validated at TU Graz and Chalmers

• Two global arrangements using as many standard components as possible were proposed. A TSFC reduction of 5.4% was computed. Further



were proposed. A TSFC reduction of 5.4% was computed. Further optimisation and combination with other technologies (larger BPR, Geared TF) could push this point further.

• PDC is still low TRL. There is a strong drawback in terms of pollutant emissions. There is a strong effort to be done in terms of R&D.


Conclusions II

• The effect of a phase shift of the firing tubes was performed to reduce the intermittency of the outlet flow and make it more acceptable for gas turbine operation. It sounds promising while peak transients are reduced and mixing is enhanced. However the complexity in terms of measurements and controls is larger.



• The impact in terms of loss of turbine efficiency because of the flow intermittency remains bounded: less than 4%.

• Proposal: more research on pulse detonation


More research on pulse detonation. Why?

• There is at European level a need to catch-up with this technology. NEWAC gave a good kick in that direction. TU Graz and Chalmers gathered know-how and momentum. Let us make good use of it. Let us do experiments.

• The PDC concept opens the door towards an extremely refined combustion control (number of tubes active, air split, frequency, firing sequence). What



• Less Nox is possible, probably at the cost of a degradation of thermal efficiency

• For the researcher: towards a better understanding of combustion processes. For the engineer: towards beautiful machines.

control (number of tubes active, air split, frequency, firing sequence). What is learned there can also be a benefit to conventional cycles

mfuel

mair

Eignition

Qheat

Low-Nox PDE concept proposed by TU Graz, usinga partial recirculation of burnt gases with depleted

oxygen in the tube inlet


Reports and articles on WP2.3.3

Lang, A., Giuliani, F., Lei, X., and Grönstedt, T. (2008). WP2.3 - 2.3.3. Basic configuration for innovative combustion. Technical Report TUG-DEL-2.3.3.A, EU IP NEWAC - FP6-030876.

Giuliani, F. and Lang, A. (2010). WP2.3 - 2.3.3. Final Assessments for Innovative Combustion. Technical Report TUG-DEL-2.3.3.B, EU IP NEWAC -FP6-030876.



FP6-030876.

Giuliani, F., Lang, A., Irannezhad, M., and Grönstedt, T. (2009). Effect of a controlled phase-shift on the outlet conditions of a set of pulse detonators. In 19th ISABE Conference, Montreal, Canada. ISABE-2009-1315.

Giuliani, F. and Lang, A. et al. (2010). Pulse detonation as an option for future innovative gas turbine combustion technologies: a concept assessment. In 27th Congress of the International Council of the Aeronautical Sciences -ICAS. Ongoing.


Thank you for your attention

Your Combustion Department at the Institute for Thermal Turbomachinery and Machine Dynamics, TU Graz


Fabrice Giuliani, 08.06.2010

TTM TU Graz

• Contact: [email protected]

• Visit our homepage at:www.TTM.TUGraz.at


COUVERTURE



COUVERTURE


Engine Scheme

Fan LPC LPTHPC HPT

CC

ConventionalAero Engine

• Introduction •••• Hybrid PDE Sizing

•••• Hybrid Engine Concept •••• Effects of a variable phase-shift on the conditions in the far field

•••• Simulation Tools •••• Conclusion



Larger BPR

Smaller HPC

Split Main/Cooling

air

Further compressed cooling air

PDC HybridAero Engine


Temperature-Entropy-Diagram of a Hybrid Engine

Entropy(s-s

0)/c

p

Te

mp

era

ture

T/T

0

SHOCK WAVE

RAYLEIGH HEAT ADDITION

HPT




partial expansion,mixing and cooling

Tem

pera

ture

T/T

_0



Entropy(s-s

0)/c

p

Te

mp

era

ture

T/T

0

INLET

FAN

IPC

HPC

HPT

LPT

EXHAUST NOZZLE

cooling

Tem

pera

ture

T/T

_0

Entropy (s-s_0)/cp


Split of the air mass flow inside the core

• Mass flow of the core– 80% for the PDE tubes

– 20% cooling air for diluting the PDE gases

• Mass flow of the PDE tubes (80%)






• Mass flow of the PDE tubes (80%)– 40% reacting air mass flow

– 40% buffer air

mco

re

mpd

e

mcoolingmbypas

sm0


• Reference Aarnio et al. 1996

• 1 Tube

• Tube length 1.2m

G2D validation case I






• Tube diameter 0.05m

Air inlet

H2 inlet Pulse Detonation Tube Straight diffuser

Controlled valves

Ignition

Ref. measurement probe

Probes

0.08m 1.05m 1.55m

Ambient


• Diffuser angle 0 deg

• Mixture: Air + H2, at stochiometric conditions

• Inlet conditions: 1bar, 300K

G2D validation case II






• Frequency 5 Hz

Air inlet


Controlled valves

Ignition


Probes

0.08m 1.05m 1.55m

Ambient


Conditions of the simulation at TU Graz

Parameter Dimension

Ref. Aarnio et al (1996) This study

Tube number [-] 1 1 to 4

Phase shifts between tubes [radians] - 0, 2π/2, 2π/3,2π/4

Tube length [m] 1.200

Tube diameter [m] 0.050


Diffuser length [m] 0.300

Diffuser angle [degrees] 0 5

Mixture Air + H2, at stoichiometric mixture conditions

Inlet conditions Ambient air pressure and temperature (10^5 Pa, 300 K)

Frequency [Hz] 5 50

Ratio mixing/puffer air No data, assumed to be 1/1

Probes [-] 7 4

Inlet velocity [m/s] No data, assumed 40 m/s


• Peak pressure: 17 bar reported, 18 bar simulated

• Peak decay specific times: 0.2 s

• Resonant effects reproduced

G2D validation case III

20

25

Pre

ssu

re [b

ar]

Probe No 2 at x=1.05m






• Peak velocities differ fromapproximately 10%

2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.80

5

10

15

Time (s)P

ress

ure

[ba

r]


• Simulation results compared with the expected Chapman-Jouguet Conditions

G2D validation case IV

Shock velocity [m/s] 1130,6 1145,6 1,33%Peak temperature [K] 2956 3127 5,78%

DeltaChapman Jouguet

TheorySimulation

Probes 1 and 2






Peak temperature [K] 2956 3127 5,78%Peak pressure [bar] 15,1 15,7 3,97%Mach number [-] 1 0,95 -5,00%

Air inlet


Controlled valves

Ignition


Probes

0.08m 1.05m 1.55m

Ambient


Pulse Detonation Combustor - turbine interaction

Static Temperature Static Pressure

•2-D CFD combustor & stator•Turbine rotor loss modeled with a re-calibrated Kacker and Okapuu correlation

•Combustor pressure ratio 1.45 •Turbine efficiency reduced 3.85%


373737

2 MPa 12 MPa1000K 4000K


• Hot (detonated) gases and cold (buffer) air are mixed at constant volume(through the detonation tube and diffuser)

• Exhaust and cooling air are mixed at constant pressure(inside the settling chamber)

Assumptions and Assessments I






• PM suggests an HPC pressure ratio of 6

• Maximum number of tubes 40


• PDE tube size– Length 1 m

– Diameter 0.05 m

• Core air split

Assumptions and Assessments II






• Core air split– 20% cooling

– 80% PDE40% reacting air | 40% buffer air


• Reacting mixture: H2 + Air

• Equivalence ratio φ=1

• Process frequency up to 60 Hz

Assumptions and Assessments III






• Inlet Mach number 0.3– 80% of the tube can be filled with fresh reactants

– Fill-time below 10 ms (self ignition time)


• Single PDE design in analogy with Aarnio et al. except a conical diffuser(surface ratio 5.5)

• Bluff-Body at the diffuser-outlet is introduced• Enhanced turbulence level

Pulse Detonation Combustor Mesh I






• Allow wall cooling in further work

• Single sector tube consists of 35,000 nodes

• Largest cell dimension is 2.5 mm


• Mesh pattern is mirrored for multi-tube configuration

• Lateral boundary conditions along the ambient domain are periodic(force symmetry)

Pulse Detonation Combustor Mesh II







Effects of a variable phase-shift on the conditions in the far field






the conditions in the far field


Setup




• Tube dimensions as described before

• Detonation rate 50 Hz

• Sequence phase shift– 0 π



– 0 π

– 2π/2

– 2π/3

– 2π/4


Phase shift 0 π







Phase shift 2 π/2







Phase shift 2 π/3







Phase shift 2 π/4







Conclusion






Conclusion


Institute for ThermalTurbomachinery andMachine Dynamics

Acknowledgments

This study realised at TU Graz in cooperation with Chalmers was supported by



This study realised at TU Graz in cooperation with Chalmers was supported by the

European Commission as part of the Integrated Project

”New Aero engine Core Concepts”(NEWAC, AIP5-CT-2006-030876)





Phase shift 0 π




Phase shift 2 π/2







Phase shift 2 π/3







Phase shift 2 π/4






Documents

37_Pulse Detonation Core Engine - Home | · PDF fileEuropean Workshop on New Aero Engine Concepts Munich, 30 June – 1 July 2010 Pulse detonation What pulse detonation is a) The detonation