supersonic combustion
Download
Skip this Video
Download Presentation
Supersonic Combustion

Loading in 2 Seconds...

play fullscreen
1 / 63

Supersonic Combustion - PowerPoint PPT Presentation


  • 252 Views
  • Uploaded on

Supersonic Combustion. Theresita Buhler Sara Esparza Cesar Olmedo. 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

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Supersonic Combustion' - Audrey


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
supersonic combustion
NASA Grant URC NCC NNX08BA44A

Supersonic Combustion

Theresita Buhler

Sara Esparza

Cesar Olmedo

supersonic outline
NASA Grant URC NCC NNX08BA44A

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

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

Supersonic Outline
hypersonic vehicle
NASA Grant URC NCC NNX08BA44AHypersonic 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

combustion
NASA Grant URC NCC NNX08BA44ACombustion
  • Fuel
  • Air
  • Heat
  • High pressure flow, at high compression
  • Quickly changing conditions
  • Temperature difficulties
    • Frictional heating
    • High forced convection
  • Highly turbulent
  • Shock
engine parameters
NASA Grant URC NCC NNX08BA44AEngine 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

jet engines
NASA Grant URC NCC NNX08BA44AJet 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
ramjet
NASA Grant URC NCC NNX08BA44ARamjet
  • 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
scramjet
NASA Grant URC NCC NNX08BA44AScramjet
  • 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
what is supersonic combustion
NASA Grant URC NCC NNX08BA44AWhat is Supersonic Combustion

Combustion maintained at supersonic speed

How is it achieved?

Design

Shockwave

Fuel Injector

Detonation Combustion

shock waves
NASA Grant URC NCC NNX08BA44A

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

Shock Waves
shock waves1
NASA Grant URC NCC NNX08BA44A

Oblique shock

Mach number decreases

Pressure, temperature, and density increase

Expansion wave

Mach number increases

Pressure, temperature, and density decrease

Shock Waves
diffuser development
NASA Grant URC NCC NNX08BA44ADiffuser Development
  • Wind tunnel specifications
    • Inlet speed
      • Mach 4.5
    • Cross-sectional area
      • 6 x 6 in
    • Length of test section
      • 10 in
design of diffuser
NASA Grant URC NCC NNX08BA44ADesign 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°

design of diffuser1
NASA Grant URC NCC NNX08BA44ADesign 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
inefficient designs
NASA Grant URC NCC NNX08BA44AInefficient Designs

Bow Shock – Cowl Interference

Oblique Shock – Cowl Spillage

cosmos flowork analysis
NASA Grant URC NCC NNX08BA44ACosmos Flowork Analysis

Velocity Profile

Mach Speed Profile

cosmos flowork analysis2
NASA Grant URC NCC NNX08BA44ACosmos Flowork Analysis

Temperature Contours

Inlet Mach = 4.5

combustion1
NASA Grant URC NCC NNX08BA44ACombustion
  • 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
    • Hydrogen
  • In scramjets, combustion is often incomplete due to the very short combustion period.
  • Equivalence ratio
    • Should range from .2 -2.0 for combustion to occur with a useful time scale
    • Lean mixture ratio below 1
    • Rich mixture ratio above 1
combustion parallel mixing
NASA Grant URC NCC NNX08BA44ACombustionParallel 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

combustion parallel mixing1
NASA Grant URC NCC NNX08BA44ACombustionParallel 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

combustion parallel mixing2
NASA Grant URC NCC NNX08BA44ACombustionParallel 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

combustion parallel mixing5
NASA Grant URC NCC NNX08BA44A

y

B1

Ya

Ya

U1

x

δm

U2

-B2

B1+B2

X=Lm

X=0

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
combustion parallel mixing6
NASA Grant URC NCC NNX08BA44A

y

B1

Ya

Ya

U1

x

δm

U2

-B2

B1+B2

X=Lm

X=0

Combustion Parallel Mixing

Mixing layer thickness equation

Estimate injector height, B1+B2=B

to reduce mixing length, Lm

combustion parallel mixing7
NASA Grant URC NCC NNX08BA44ACombustion Parallel Mixing

Manifolding idea

Multiple inlets

Reduce mixing length

Tradeoff: Inefficient design

Adds bulk and volume

Air

δm

B

Fuel

δm

Air

Fuel

combustion laminar shear mixing
NASA Grant URC NCC NNX08BA44ACombustion 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

combustion turbulent shear mixing
NASA Grant URC NCC NNX08BA44ACombustion 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
combustion turbulent shear mixing2
NASA Grant URC NCC NNX08BA44ACombustionTurbulent Shear Mixing
  • Mean velocity profile combines
    • Prandtl’s number
    • Turbulent kinematic viscosity
    • Time average characteristics of turbulent shear

Micro-mixing

Fuel wave

Fuel vortex

combustion turbulent shear mixing3
NASA Grant URC NCC NNX08BA44ACombustionTurbulent Shear Mixing

Shear layer width – Two methods

Local shear layer width for turbulent shear mixing

Recent research

Cδ is a experimental constant

combustion turbulent shear mixing4
NASA Grant URC NCC NNX08BA44ACombustionTurbulent 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
combustion turbulent shear mixing5
NASA Grant URC NCC NNX08BA44ACombustionTurbulent Shear Mixing
  • Convective velocity for the vortex structures
  • With compressible flow using isentropic stagnation density equation changes to
combustion turbulent shear mixing6
NASA Grant URC NCC NNX08BA44ACombustionTurbulent Shear Mixing
  • Density correct expression for shear layer growth including compressibility effects
combustion turbulent shear mixing8
NASA Grant URC NCC NNX08BA44A

Fuel

CombustionTurbulent Shear Mixing

Based on what we know the angle of our hydrogen injection should be

To produce a hydrogen rich mixture

Lm, F

air

Lm, A

diffusion combustion
NASA Grant URC NCC NNX08BA44A

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

Diffusion Combustion
diffusion combustion1
NASA Grant URC NCC NNX08BA44ADiffusion Combustion
  • Symmetric flame
  • Stoichiometric ratio
    • Varies across flame
  • Flame center
    • Highest temperature, fuel
  • Air lost around edges
conductive combustion
NASA Grant URC NCC NNX08BA44AConductive Combustion
  • Diffusion and premixed combined
  • Stoichiometric ratio
    • Determined by pre-mixture
  • Flame center
    • Highest temperature, fuel
  • Air lost around edges
supersonic wind tunnel
NASA Grant URC NCC NNX08BA44ASupersonic Wind Tunnel

Commission of pressure tank

Team

Assistant dean Don Maurizio

Technician Sheila Blaise

Professor Chivey Wu

Wind tunnel team : Long Ly, Nhan Doan

fuel supply
NASA Grant URC NCC NNX08BA44AFuel Supply
  • Follows test rig of wind tunnel
  • Stainless steel lines
    • Leak proof
    • Tank pressure
hydrogen
NASA Grant URC NCC NNX08BA44AHydrogen

Scramjet X-43

Expensive fuel

Much less emissions than hydrocarbons

Dangerous

Invisible flame

Detailed analysis

Calculations & numerical

Safety procedures

Experimental

Safety analysis

hydrogen safety equipment
NASA Grant URC NCC NNX08BA44AHydrogen Safety Equipment

Tank

Carbon fiber, non-burst tank

Liquid check valve

Gas flashback arrestor

Infrared camera

FLIR Thermacam

$3,500.0

materials
NASA Grant URC NCC NNX08BA44AMaterials

Hastelloy

Nickel Steel

Reinforced carbon-carbon

BMI

Stainless steel 430

future work
NASA Grant URC NCC NNX08BA44AFuture 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
dramatic quotes
NASA Grant URC NCC NNX08BA44ADramatic 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

textbook references
NASA Grant URC NCC NNX08BA44ATextbook 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. 1999.

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”.

journal references
NASA Grant URC NCC NNX08BA44AJournal 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. 2005-4105.

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, 64-579, 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. 1988.

Ilbas, M., “The Effect of Thermal Radiation and Radiation Models on Hydrogen-Hydrocarbon Combustion Modeling” International Journal of Hydrogen Energy. Vol 30, Pgs. 1113-1126. 2005.

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-2006-271. 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 2005-3358, 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.

acknowledgements
NASA Grant URC NCC NNX08BA44AAcknowledgements

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

ad