European Workshop on New Aero Engine Concepts Munich, 30 June 1 July PDF Free Download

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, Austria T. Grönstedt, M. Irannezhad, Chalmers University, Sweden

Contents Pulse detonation Literature survey statistics Hybrid engine concept Intermittent flow analysis Conclusions and recommendations

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 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 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? Knowing that : Higher predicted thermal efficiency 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 Low TRL technology Non-conventional fuel so far Flow intermittency Stoichiometry + peak T >> 2000 K -> NOx Pressure gain -> need of compressing the cooling air Complexity of cycle control Noise

Contents Pulse detonation Literature survey statistics Hybrid engine concept Intermittent flow analysis Conclusions and recommendations

Literature survey - Statistics

Contents Pulse detonation Literature survey statistics Hybrid engine concept Intermittent flow analysis Conclusions and recommendations

Hybrid engine concept

Hybrid engine concept Reference test case 2000 1800 1600 1400 Entropy - Temperature Diagram (Reference) Engine Net Thrust: 122.53 [kn] Equivalence Ratio (φ): 0.33 [-] Thrust Specific Fuel Consumption (TSFC): 13.23 [mg/(n*s)] p 5 =32.97 [bar] 5 Temperature [K] 1200 1000 800 600 400 200 0 2 3 018bp p 4 =34.7 [bar] 4 p 3 =2.35 [bar] p 2 =1.53 [bar] p 1 =1.06 [bar] p amb =1.01 [bar] p 6 =9.02 [bar] 6 p 7 =3.63 [bar] 7 p 8c =1.94 [bar] 8c 0 500 1000 1500 Entropy [J/(kg*K)]

Hybrid engine concept Option 1: Same TSFC, lighter frame Temperature [K K] 2000 1800 1600 1400 1200 1000 800 600 400 200 0 Entropy - Temperature Diagram (PDE - Case 1) Engine Net Thrust: 122.53 [kn] Equivalence Ratio (φ): 0.33 [-] Thrust Specific Fuel Consumption (TSFC): 13.2 [mg/(n*s)] Nondimensional heat added (q): 5.07 [-] p amb =1.01 [bar] p 3 =2.35 [bar] p 2 =1.53 [bar] p 5 =27.91 [bar] 5 p 6 =9.74 [bar] 6 p 7 =3.82 [bar] 7 p 8c =2.07 [bar] 8c p 4 =17.35 [bar] 4 Temperature ratio of compression (ψ): 2.36 [-] 2 3 018bp Peak Pressure after the Rayleigh Heat Addition: 132.36 [bar] p 1 =1.06 [bar] Peak Temperature after the Rayleigh Heat Addition: 2584 [K] Pressure ratio of the PDE: 1.6 [-] 0 500 1000 150 Entropy [J/(kg*K)]

Hybrid engine concept Option 2: Lower TSFC, heavier frame 2000 1800 Entropy - Temperature Diagram (PDE- Case 2) Engine Net Thrust: 122.53 [kn] Equivalence Ratio (φ): 0.32 [-] Thrust Specific Fuel Consumption (TSFC): 12.51 [mg/(n*s)] Temperatu ure [K] 1600 1400 1200 1000 800 600 400 200 0 p amb =1.01 [bar] p 4 =34.7 [bar] 4 p 3 =2.35 [bar] p 5 =46.13 [bar] 5 p 6 =10.77 [bar] 6 p 7 =4.11 [bar] 7 p 8c =2.22 [bar] 8c Nondimensional heat added (q): 4.06 [-] Temperature ratio of compression (ψ): 2.87 [-] p 2 =1.53 [bar] 2 3 018bp Peak Pressure after the Rayleigh Heat Addition: 193.42 [bar] Peak Temperature after the Rayleigh Heat Addition: 2421 [K] p 1 =1.06 [bar] Pressure ratio of the PDE: 1.3 [-] 0 500 1000 1500 Entropy [J/(kg*K)]

Hybrid engine concept ASSESSMENTS Lighter frame Less TSFC TSFC same -5,4% NOx +85,2% +97,1% Mass -6,5% +12,7% Length* -10% +1,2% 40 PDE s PDC collector and relaxation chamber HPC casing * Provided the assumption of bended tubes is valid Injection modules (one per tube)

Contents Pulse detonation Literature survey statistics Hybrid engine concept Intermittent flow analysis Conclusions and recommendations

Intermittent flow analysis G2D Unsteady RANS Solver developed at Chalmers University Used for 2D simulation of detonation tubes Time sequence per detonation cycle (here operation at 62.5Hz) 18

Intermittent flow analysis 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 19

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

Intermittent flow analysis Pulse Detonation Combustor - turbine interaction Turbine rotor loss modeled after Kacker and Okapuu (1982) -> 3.85% HPT efficiency loss

Contents Pulse detonation Literature survey statistics Hybrid engine concept Intermittent flow analysis Conclusions and recommendations

Conclusions European Workshop on New Aero Engine Concepts 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 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. 23

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 24

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 knowhow 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 is learned there can also be a benefit to conventional cycles Less Nox is possible, probably at the cost of a degradation of thermal efficiency m fuel Q heat For the researcher: towards a better understanding of combustion processes. For the engineer: towards beautiful machines. m air E ignition Low-Nox PDE concept proposed by TU Graz, using a partial recirculation of burnt gases with depleted oxygen in the tube inlet 25

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. 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. 26

Thank you for your attention Your Combustion Department at the Institute for Thermal Turbomachinery and Machine Dynamics, TU Graz Contact: Fabrice.Giuliani@TUGraz.at Visit our homepage at: www.ttm.tugraz.at TTM TU Graz Fabrice Giuliani, 08.06.2010

COUVERTURE 28

Introduction European Workshop on New Aero Engine Concepts Hybrid Engine Concept Effects Munich, of a variable 30 phase-shift June on 1 the July conditions 2010in the far field Simulation Tools Engine Scheme Hybrid PDE Sizing Conclusion CC Conventional Aero Engine Fan LPC HPC HPT LPT Larger BPR PDC Hybrid Aero Engine Smaller HPC Split Main/Cooling air Further compressed cooling air 29

Introduction Hybrid PDE Sizing European Workshop on New Aero Engine Concepts Hybrid Engine Concept Effects Munich, of a variable 30 phase-shift June on 1 the July conditions 2010in the far field Simulation Tools Conclusion Temperature-Entropy-Diagram of a Hybrid Engine RAYLEIGH HEAT ADDITION Temperature T/T 0 Temperature T/T 0 SHOCK WAVE partial expansion, mixing and cooling HPT LPT EXHAUST NOZZ HPC IPC FAN INLET Entropy (s-s 0 )/c p Entropy (s-s_0)/c p 30

Introduction European Workshop on New Aero Engine Concepts Hybrid Engine Concept Effects Munich, of a variable 30 phase-shift June on 1 the July conditions 2010in the far field Simulation Tools Hybrid PDE Sizing Conclusion 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%) 40% reacting air mass flow 40% buffer air m 0 m bypas s m cooling m co re m pd 31 e

Introduction Hybrid Engine Concept Simulation Tools Hybrid PDE Sizing European Workshop on New Aero Engine Concepts Effects Munich, of a variable 30 phase-shift June on 1 the July conditions 2010in the far field Conclusion G2D validation case I Reference Aarnio et al. 1996 1 Tube Tube length 1.2m Tube diameter 0.05m Probe s 0.08m 1.05m 1.55m Controlled valves Air inlet Ignitio n Ref. measurement probe H 2 inlet Pulse Detonation Tube Straight diffuser Ambient 32

Introduction Hybrid Engine Concept Simulation Tools European Workshop on New Aero Engine Concepts Effects Munich, of a variable 30 phase-shift June on 1 the July conditions 2010in the far field G2D validation case II Diffuser angle 0 deg Hybrid PDE Sizing Conclusion Mixture: Air + H 2, at stochiometric conditions Inlet conditions: 1bar, 300K Frequency 5 Hz Probe s 0.08m 1.05m 1.55m Controlled valves Air inlet Ignitio n Ref. measurement probe H 2 inlet Pulse Detonation Tube Straight diffuser Ambient 33

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

Introduction Hybrid Engine Concept Simulation Tools Hybrid PDE Sizing European Workshop on New Aero Engine Concepts Effects Munich, of a variable 30 phase-shift June on 1 the July conditions 2010in the far field Conclusion G2D validation case III Peak pressure: 17 bar reported, 18 bar simulated Peak decay specific times: 0.2 s 25 Probe No 2 at x=1.05m Resonant effects reproduced 20 Peak velocities differ from approximately 10% ] Pressure [bar] 15 10 5 0 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Time (s) 35

Introduction Hybrid Engine Concept Simulation Tools Hybrid PDE Sizing European Workshop on New Aero Engine Concepts Effects Munich, of a variable 30 phase-shift June on 1 the July conditions 2010in the far field Conclusion G2D validation case IV Simulation results compared with the expected Chapman-Jouguet Conditions Chapman Jouguet Simulation Delta Theory Probes 1 and 2 Shock velocity [m/s] 1130,6 1145,6 1,33% Peak temperature [K] 2956 3127 5,78% Peak pressure [bar] 15,1 15,7 3,97% Mach number [-] 1 0,95-5,00% Probe s 0.08m 1.05m 1.55m Controlled valves Air inlet Ignitio n Ref. measurement probe H 2 inlet Pulse Detonation Tube Straight diffuser Ambient 36

Pulse Detonation Combustor - turbine interaction 2-D CFD combustor & stator Turbine rotor loss modeled with a recalibrated Kacker and Okapuu correlation Static Temperature Combustor pressure ratio 1.45 Turbine efficiency reduced 3.85% Static Pressure 1000K 4000K 2 MPa 12 MPa 37

Introduction Hybrid Engine Concept Simulation Tools Hybrid PDE Sizing European Workshop on New Aero Engine Concepts Effects Munich, of a variable 30 phase-shift June on 1 the July conditions 2010in the far field Conclusion Assumptions and Assessments I 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) PM suggests an HPC pressure ratio of 6 Maximum number of tubes 40 38

Introduction Hybrid Engine Concept Simulation Tools European Workshop on New Aero Engine Concepts Effects Munich, of a variable 30 phase-shift June on 1 the July conditions 2010in the far field Assumptions and Assessments II PDE tube size Length 1 m Hybrid PDE Sizing Conclusion Diameter 0.05 m Core air split 20% cooling 80% PDE 40% reacting air 40% buffer air 39

Introduction Hybrid Engine Concept Simulation Tools Hybrid PDE Sizing European Workshop on New Aero Engine Concepts Effects Munich, of a variable 30 phase-shift June on 1 the July conditions 2010in the far field Conclusion Assumptions and Assessments III Reacting mixture: H 2 + Air Equivalence ratio φ=1 Process frequency up to 60 Hz Inlet Mach number 0.3 80% of the tube can be filled with fresh reactants Fill-time below 10 ms (self ignition time) 40

Introduction Hybrid Engine Concept Simulation Tools Hybrid PDE Sizing European Workshop on New Aero Engine Concepts Effects Munich, of a variable 30 phase-shift June on 1 the July conditions 2010in the far field Conclusion Pulse Detonation Combustor Mesh I 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 Allow wall cooling in further work Single sector tube consists of 35,000 nodes Largest cell dimension is 2.5 mm 41

Introduction Hybrid Engine Concept Simulation Tools Hybrid PDE Sizing European Workshop on New Aero Engine Concepts Effects Munich, of a variable 30 phase-shift June on 1 the July conditions 2010in the far field Conclusion Pulse Detonation Combustor Mesh II Mesh pattern is mirrored for multi-tube configuration Lateral boundary conditions along the ambient domain are periodic (force symmetry) 42

Introduction Hybrid Engine Concept Simulation Tools Hybrid PDE Sizing European Workshop on New Aero Engine Concepts Effects Munich, of a variable 30 June phase-shift 1 on July the conditions 2010 in the far field Conclusion Effects of a variable phase-shift on the conditions in the far field 43

Introduction Hybrid Engine Concept Simulation Tools Setup Hybrid PDE Sizing European Workshop on New Aero Engine Concepts Effects Munich, of a variable 30 June phase-shift 1 on July the conditions 2010 in the far field Conclusion Tube dimensions as described before Detonation rate 50 Hz Sequence phase shift 0 π 2π/2 2π/3 2π/4 44

Introduction Hybrid Engine Concept Simulation Tools European Workshop on New Aero Engine Concepts Effects Munich, of a variable 30 June phase-shift 1 on July the conditions 2010 in the far field Phase shift 0 π Hybrid PDE Sizing Conclusion 45

European Institute for Thermal Workshop on New Aero Engine Concepts Turbomachinery and Machine Dynamics Acknowledgments 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) 50

European Workshop on New Aero Engine Concepts Munich, 30 June 1 July 2010