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Supersonic Combustion

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1 Supersonic Combustion
Theresita Buhler Sara Esparza Cesar Olmedo 10/29/2009 NASA Grant URC NCC NNX08BA44A

2 NASA Grant URC NCC NNX08BA44A
Supersonic Outline Engine: Cowl design Combustion schemes & fuels Exhaust: Expansion Prototype design Materials Design Specifications Installation in the wind tunnel Location Fuel lines and ignition wires Hydrogen safety History Cost Acknowledgements Questions Purpose & Goals Introduction to combustion Engine parameters Jet Engine Ramjet Scramjet Jet Engine vs. Scramjet Model Reference stations Analytical approach Compressible flow Shockwaves Inlet: Diffuser design COSMOSWorks design ADD PICTURE OF OVER-EXPOSED DIFFUSER 10/29/2009 NASA Grant URC NCC NNX08BA44A

3 NASA Grant URC NCC NNX08BA44A
Hypersonic Vehicle High speed travel Commercial flight Reaction engines Circumnavigation in four hours NASA Goals Global reach vehicle Reduced emissions Challenges Shockwaves High heat Combustion instability Flight direction control NASA X-43 Vehicle NASA X-51 Testing 10/29/2009 NASA Grant URC NCC NNX08BA44A

4 NASA Grant URC NCC NNX08BA44A
Combustion Fuel Air Heat High pressure flow, at high compression Quickly changing conditions Temperature difficulties Frictional heating High forced convection Highly turbulent Shock ADD PICTURE FOR COMBUSTION 10/29/2009 NASA Grant URC NCC NNX08BA44A

5 Engine Parameters Fit engine to aerospace system
Jet Engines – Low orbit, max Mach 3 Ramjets – High altitude, supersonic flight, subsonic combustion Scramjets – High altitude, hypersonic flight, supersonic combustion 10/29/2009 NASA Grant URC NCC NNX08BA44A

6 NASA Grant URC NCC NNX08BA44A
Jet Engines Combustion chamber Introduce fuel House combustion Turbine blades Capture expansion of exhaust gases Inlet design Feed air into chamber Compressor blades Increase pressure of flow Cesar Olmedo 10/29/2009 NASA Grant URC NCC NNX08BA44A

7 NASA Grant URC NCC NNX08BA44A
Ramjet Vehicle travels at supersonic speed Simplest air-breathing engine No moving parts Compression of intake achieved by supersonic flow – inlet speed reduction Shockwave system Relatively low velocity Combustions at subsonic speeds Very high reduction in speed High drag High fuel consumption Temperature at 3000 K (4940°F) Diffuser Exit plane contracts Exhaust at supersonic speed Travel: M = 3 Combustion: M= 0.3 10/29/2009 NASA Grant URC NCC NNX08BA44A

8 NASA Grant URC NCC NNX08BA44A
Scramjet Hypersonic flight No moving parts Combustion at Supersonic speed Flow ignites supersonically Fuel injection into supersonic air stream Steer clear of shock waves Is Aerodynamically challenged 10/29/2009 NASA Grant URC NCC NNX08BA44A

9 NASA Grant URC NCC NNX08BA44A
Scramjet Boeing 10/29/2009 NASA Grant URC NCC NNX08BA44A

10 NASA Grant URC NCC NNX08BA44A
Then and Now 10/29/2009 NASA Grant URC NCC NNX08BA44A

11 What is Supersonic Combustion
Combustion maintained at supersonic speed How is it achieved? Design Shockwave Fuel Injector Detonation Combustion 10/29/2009 NASA Grant URC NCC NNX08BA44A

12 NASA Grant URC NCC NNX08BA44A
Shock Waves Oblique shocks Mach number decreases Pressure, temperature, and density increase Attached to vehicle Normal shocks Mach number decreases Pressure, temperature, and density increase Creates subsonic region in front of nose Detached 10/29/2009 NASA Grant URC NCC NNX08BA44A

13 NASA Grant URC NCC NNX08BA44A
Shock Waves Oblique shock Mach number decreases Pressure, temperature, and density increase Expansion wave Mach number increases Pressure, temperature, and density decrease 10/29/2009 NASA Grant URC NCC NNX08BA44A

14 NASA Grant URC NCC NNX08BA44A
Diffuser Development Wind tunnel specifications Inlet speed Mach 4.5 Cross-sectional area 6 x 6 in Length of test section 10 in 10/29/2009 NASA Grant URC NCC NNX08BA44A

15 NASA Grant URC NCC NNX08BA44A
Design of Diffuser Initial design of diffuser Use manifold design to introduce fuel Diffuser was designed in to two separate pieces Goal Seek 18° 28.29° 19.67° 10/29/2009 NASA Grant URC NCC NNX08BA44A

16 NASA Grant URC NCC NNX08BA44A
Design of Diffuser Top part of the diffuser Has machined holes for fuel and ignition wires. Also four holes for securing the base of the diffuser 10/29/2009 NASA Grant URC NCC NNX08BA44A

17 NASA Grant URC NCC NNX08BA44A
Design of Diffuser 10/29/2009 NASA Grant URC NCC NNX08BA44A

18 NASA Grant URC NCC NNX08BA44A
2D Shockwaves 10/29/2009 NASA Grant URC NCC NNX08BA44A

19 NASA Grant URC NCC NNX08BA44A
Inefficient Designs Bow Shock – Cowl Interference Oblique Shock – Cowl Spillage 10/29/2009 NASA Grant URC NCC NNX08BA44A

20 Cosmo Flowork Analysis
Mesh used by Cosmo to perform calculation on the diffuser. 10/29/2009 NASA Grant URC NCC NNX08BA44A 20

21 Cosmos Flowork Analysis
Do we need a scale ? To determine the magnitude on this pictures? Velocity Profile Mach Speed Profile 10/29/2009 NASA Grant URC NCC NNX08BA44A 21

22 Cosmos Flowork Analysis
Pressure Profile of original Design Pressure Contours Inlet Mach = 4.5 10/29/2009 NASA Grant URC NCC NNX08BA44A 22

23 Cosmos Flowork Analysis
Temperature profile of original design Temperature Contours Inlet Mach = 4.5 10/29/2009 NASA Grant URC NCC NNX08BA44A 23

24 Cosmos Flowork Analysis
10/29/2009 NASA Grant URC NCC NNX08BA44A

25 NASA Grant URC NCC NNX08BA44A
Ramp Fuel Injections Ramped Outward Ramped Inward 10/29/2009 NASA Grant URC NCC NNX08BA44A

26 Cosmos Flowork Analysis
Mach sped 10/29/2009 NASA Grant URC NCC NNX08BA44A

27 Cosmos Flowork Analysis
Pressure 10/29/2009 NASA Grant URC NCC NNX08BA44A

28 Cosmos Flowork Analysis
Density 10/29/2009 NASA Grant URC NCC NNX08BA44A

29 Cosmos Flowork Analysis
Velocity 10/29/2009 NASA Grant URC NCC NNX08BA44A

30 NASA Grant URC NCC NNX08BA44A
Combustion Combustion Stoichiometry Ideal fuel/ air ratio Recommended fuel for scramjets Hydrogen Methane Ethane Hexane Octane Only Oxidizer is Air Maximum combustion temperature Hydrocarbon atoms are mixed with air so Hydrogen atoms form water Oxygen atoms form carbon dioxide Most common fuel for scramjets In scramjets, combustion is often incomplete due to the very short combustion period. Equivalence ratio Should range from for combustion to occur with a useful time scale Lean mixture ratio below 1 Rich mixture ratio above 1 10/29/2009 NASA Grant URC NCC NNX08BA44A

31 Combustion Parallel Mixing
Fuel- Air Mixing at mach speeds Gas phase chemical reaction occurs by the exchange of atoms between molecules as a results of molecular collisions. The fuel and air must be mixed at near-stoichiometric proportions before combustion can occur Parallel Mixing of Fuel- Air U1 Mixing Layer δm U2 10/29/2009 NASA Grant URC NCC NNX08BA44A

32 Combustion Parallel Mixing
Zero shear mixing Both air and fuel velocities are equal Shear stress doesn’t exist between streams Coflow occurs Lateral transport Occurs by molecular diffusion At fuel – air interface No momentum or vorticity transfer Axial development of cross –stream profiles of air mole fraction YA in Zero shear (U1=U2) Fuel Mole fraction Profile is YF=1-YA Mirror Image Ya Ya U1 δm U2 10/29/2009 NASA Grant URC NCC NNX08BA44A

33 Combustion Parallel Mixing
Molecular diffusion Fick’s Law Air molecular transport rate into fuel Proportional to the interfacial area times the local concentration gradient. Proportionality constant DFA, = molecular diffusivity Where DFA*ρ is approximately equal to molecular viscosity μ for most gases Ya Ya U1 δm U2 10/29/2009 NASA Grant URC NCC NNX08BA44A

34 Combustion Parallel Mixing
Fick’s law for diffusion 10/29/2009 NASA Grant URC NCC NNX08BA44A

35 Combustion Parallel Mixing
Ya Ya U1 δm U2 10/29/2009 NASA Grant URC NCC NNX08BA44A

36 Combustion Parallel Mixing
Steepest concentration gradient at x = 0 Mixing layer reaches the wall at x=Lm the air mole fraction still varies from 1.0 at y=B1 and 0 at y= -B2 More mixing is needed 2Lm is recommended by experiment enables complete micro-mixing δm U1 U2 Ya B1+B2 X=Lm B1 -B2 y x X=0 10/29/2009 NASA Grant URC NCC NNX08BA44A

37 Combustion Parallel Mixing
Mixing layer thickness equation Estimate injector height, B1+B2=B to reduce mixing length, Lm δm U1 U2 Ya B1+B2 X=Lm B1 -B2 y x X=0 You can reduce Uc, decrease B , increase Dfa or combination of all three to shorten Lm But since Uc and Dfa are effected by design and physical properties the only solid change is B by manifolding 10/29/2009 NASA Grant URC NCC NNX08BA44A

38 Combustion Parallel Mixing
Manifolding idea Multiple inlets Reduce mixing length Tradeoff: Inefficient design Adds bulk and volume Air B δm NEED TO ADD LM ON THIS ONE, CP! Fuel Air δm Fuel 10/29/2009 NASA Grant URC NCC NNX08BA44A

39 Combustion Laminar Shear Mixing
Molecular diffusion alone cannot meet the requirements of rapid lateral mixing in supersonic flow Solution shear layer between both layers U1>U2 , Uc=0.5(U1+U2 ) Velocity ratio r =(U1/U2 ) Velocity Difference Δ U= (U1-U2 ) μ: dynamic viscosity ν: kinematic viscosity 10/29/2009 NASA Grant URC NCC NNX08BA44A

40 Combustion Turbulent shear mixing
As we further increase the velocity difference delta U Shear stress causes the periodic formation of large vortices The vortex sheet between the two streams rolls up and engulfs fluid from both streams and stretches the mixant interface. Stretching of the mixant interface increases the interfacial area and steepens the concentration gradients Shear mixing increases molecular diffusion 10/29/2009 NASA Grant URC NCC NNX08BA44A

41 Combustion Turbulent shear mixing
EXPLAIN Fuel wave Fuel vortex Micro-mixing 10/29/2009 NASA Grant URC NCC NNX08BA44A

42 Combustion Turbulent Shear Mixing
Mean velocity profile combines Prandtl’s number Turbulent kinematic viscosity Time average characteristics of turbulent shear Micro-mixing Fuel wave Fuel vortex 10/29/2009 NASA Grant URC NCC NNX08BA44A

43 Combustion Turbulent Shear Mixing
Shear layer width – Two methods Local shear layer width for turbulent shear mixing Recent research Cδ is a experimental constant 10/29/2009 NASA Grant URC NCC NNX08BA44A

44 Combustion Turbulent Shear Mixing
Density effects on shear layer growth – compressible flow Based on constant but different densities A density ratio, s, is derived s can be calculated once stagnation pressure and stream velocities are known 10/29/2009 NASA Grant URC NCC NNX08BA44A

45 Combustion Turbulent Shear Mixing
Convective velocity for the vortex structures With compressible flow using isentropic stagnation density equation changes to 10/29/2009 NASA Grant URC NCC NNX08BA44A

46 Combustion Turbulent Shear Mixing
Density correct expression for shear layer growth including compressibility effects 10/29/2009 NASA Grant URC NCC NNX08BA44A

47 Combustion Turbulent Shear Mixing
EXPLAIN, CP 10/29/2009 NASA Grant URC NCC NNX08BA44A Only applies to box cowl

48 Combustion Turbulent Shear Mixing
Based on what we know the angle of our hydrogen injection should be To produce a hydrogen rich mixture Lm, F Fuel air Lm, A 10/29/2009 NASA Grant URC NCC NNX08BA44A

49 Diffusion Combustion Mixing Controlled Combustion
High mixture temperature High reaction rates Limiting feature: mixing Reaction Rate Controlled Low mixture temperature Adequate mixing Limiting feature: reaction rates Rate of heat release Picture and explanation 10/29/2009 NASA Grant URC NCC NNX08BA44A

50 NASA Grant URC NCC NNX08BA44A
Diffusion Combustion Symmetric flame Stoichiometric ratio Varies across flame Flame center Highest temperature, fuel Air lost around edges READ SECTION TO EXPLAIN FLAME BETTER 10/29/2009 NASA Grant URC NCC NNX08BA44A

51 Conductive Combustion
Diffusion and premixed combined Stoichiometric ratio Determined by pre-mixture Flame center Highest temperature, fuel Air lost around edges explanation 10/29/2009 NASA Grant URC NCC NNX08BA44A

52 Supersonic Wind Tunnel
Commission of pressure tank Team Assistant dean Don Maurizio Technician Sheila Blaise Professor Chivey Wu Wind tunnel team : Long Ly, Nhan Doan 10/29/2009 NASA Grant URC NCC NNX08BA44A

53 NASA Grant URC NCC NNX08BA44A
Apparatus 10/29/2009 NASA Grant URC NCC NNX08BA44A

54 NASA Grant URC NCC NNX08BA44A
Fuel Supply Follows test rig of wind tunnel Stainless steel lines Leak proof Tank pressure 10/29/2009 NASA Grant URC NCC NNX08BA44A

55 NASA Grant URC NCC NNX08BA44A
Hydrogen Scramjet X-43 Expensive fuel Much less emissions than hydrocarbons Dangerous Invisible flame Detailed analysis Calculations & numerical Safety procedures Experimental Safety analysis 10/29/2009 NASA Grant URC NCC NNX08BA44A

56 Hydrogen Safety Equipment
Tank Carbon fiber, non-burst tank Liquid check valve Gas flashback arrestor Infrared camera FLIR Thermacam $3,500.0 10/29/2009 NASA Grant URC NCC NNX08BA44A

57 NASA Grant URC NCC NNX08BA44A
Materials Hastelloy Nickel Steel Reinforced carbon-carbon BMI Stainless steel 430 10/29/2009 NASA Grant URC NCC NNX08BA44A

58 NASA Grant URC NCC NNX08BA44A
Costs Group Item Price Fuel Hydrogen + Regulator Catalyst - Silane $275. $125. Materials Steel $400. Manufacturing In-house Wind Tunnel Retrofit Gauges, Channels, $350. View Windows 2 Sapphire 1” x 0.375” $700. Total $1,850. 10/29/2009 NASA Grant URC NCC NNX08BA44A

59 NASA Grant URC NCC NNX08BA44A
Future Work Analytical study Compressible flow Gas dynamics Diabatic flow Chemical kinetics in supersonic flow Numerical analyses FLUENT Supersonic wind tunnel Manufacturing Compressible flow class with Dr. Wu Document calculations 10/29/2009 NASA Grant URC NCC NNX08BA44A

60 NASA Grant URC NCC NNX08BA44A
Dramatic Quotes Sustaining supersonic combustion is “like trying to light a match in a hurricane” “There is currently no conclusive evidence that these requirements can be met: nevertheless, the present study starts with the basic assumption that stable supersonic combustion in an engine is possible” Richard J. Weber 10/29/2009 NASA Grant URC NCC NNX08BA44A

61 NASA Grant URC NCC NNX08BA44A
Textbook References Anderson, J. “Compressible Flow.” Anderson, J. “Hypersonic & High Temperature Gas Dynamics” Curran, E. T. & S. N. B. Murthy, “Scramjet Propulsion” AIAA Educational Serties, Fogler, H.S. “Elements of Chemical Reaction Engineering” Prentice Hall International Studies. 3rd ed Heiser, W.H. & D. T. Pratt “Hypersonic Airbreathing Propulsion” AIAA Educational Searies. Olfe, D. B. & V. Zakkay “Supersonic Flow, Chemical Processes, & Radiative Transfer” Perry, R. H. & D. W. Green “Perry’s Chemical Engineers’ Handbook” McGraw-Hill Turns, S.R. “An Introduction to Combustion” White, E.B. “Fluid Mechanics”. 10/29/2009 NASA Grant URC NCC NNX08BA44A

62 NASA Grant URC NCC NNX08BA44A
Journal References Allen, W., P. I. King, M. R. Gruber, C. D. Carter, K. Y Hsu, “Fuel-Air Injection Effects on Combustion in Cavity-Based Flameholders in a Supersonic Flow”. 41st AIAA Joint Propulsal Billig, F. S. “Combustion Processes in Supersonic Flow”. Journal of Propulsion, Vol. 4, No. 3, May-June 1988 Da Riva, Ignacio, Amable Linan, & Enrique Fraga “Some Results in Supersonic Combustion” 4th Congress, Paris, France, , Aug 1964 Esparza, S. “Supersonic Combustion” CSULA Symposium, May 2008. Grishin, A. M. & E. E. Zelenskii, “Diffusional-Thermal Instability of the Normal Combustion of a Three-Component Gas Mixture,” Plenum Publishing Corporation Ilbas, M., “The Effect of Thermal Radiation and Radiation Models on Hydrogen-Hydrocarbon Combustion Modeling” International Journal of Hydrogen Energy. Vol 30, Pgs Qin, J, W. Bao, W. Zhou, & D. Yu. “Performance Cycle Analysis of an Open Cooling Cycle for a Scramjet” IMechE, Vol. 223, Part G, 2009. Mathur, T., M. Gruber, K. Jackson, J. Donbar, W. Donaldson, T. Jackson, F. Billig. “Supersonic Combustion Experiements with a Cavity-Based Fuel Injection”. AFRL-PR-WP-TP Nov 2001 McGuire, J. R., R. R. Boyce, & N. R. Mudford. Journal of Propulsion & Power, Vol. 24, No. 6, Nov-Dec 2008 Mirmirani, M., C. Wu, A. Clark, S, Choi, & B. Fidam, “Airbreathing Hypersonic Flight Vehicle Modeling and Control, Review, Challenges, and a CFD-Based Example” Neely, A. J., I. Stotz, S. O’Byrne, R. R. Boyce, N. R. Mudford, “Flow Studies on a Hydrogen-Fueled Cavity Flame- Holder Scramjet. AIAA , 2005. Tetlow, M. R. & C. J. Doolan. “Comparison of Hydrogen and Hydrocarbon-Fueld Scramjet Engines for Orbital Insertion” Journal of Spacecraft and Rockets, Vol 44., No. 2., Mar-Apr 2007. 10/29/2009 NASA Grant URC NCC NNX08BA44A

63 NASA Grant URC NCC NNX08BA44A
Acknowledgements Dr. H. Boussalis Dr. D. Guillaume Dr. C. Liu Dr. T. Pham Dr. C. Wu SPACE Center Students Combustion Team Wind Tunnel Team Nhan Doan Long Ly Sheila Blaise Don Roberto Cris Reid Dr. D. Blekhman Cesar Huerta Celeste Montenegro Dr. C. Khachikian Keith Bacosa D. Maurizio 10/29/2009 NASA Grant URC NCC NNX08BA44A

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