Abstract
Work has been underway for a number of years at the NASA Langley Research Center to develop a supersonic combustion ramjet or scramjet that is capable of propelling a vehicle at hypersonic speeds in the atmosphere or beyond. A recent part of that research has been directed toward the optimization of the scramjet combustor, and in particular the efficiency of fuel-air mixing and reaction in the engine. A supersonic, spatially developing and reacting mixing layer serves as an excellent physical model for the mixing and reaction processes that take place in a scramjet combustor, This paper describes a study of fuel-air mixing and reaction in a supersonic mixing layer and discusses several techniques that were applied for enhancing the mixing processes and the overall combustion efficiency in the layer. Based on the results of this study, an alternate fuel injector configuration was computationally designed, and that configuration significantly increased the amount of fuel-air mixing and combustion over a given combustor length that was achieved.
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Abbreviations
- A:
-
constant in Arrhenius law
- a:
-
speed of sound, m/s
- Cp :
-
specific heat at constant pressure, J/kg-K
- DT :
-
thermal diffusion coefficient, m2/s
- Dij :
-
binary diffusion coefficient, m2/s
- E:
-
activation energy, cal/gm-mole; total internal energy, J/kg
- →F:
-
flux vector
- fi :
-
mass fraction of species i
- GR :
-
Gibbs energy of reaction, J/kg-mole
- →H:
-
source vector
- hi :
-
enthalpy of species i, J/kg
- ho :
-
total enthalpy, J/kg
- h oi :
-
reference enthalpy at standard conditions, J/kg
- I:
-
identity matrix
- K:
-
equilibrium constant
- kb :
-
reverse reaction rate
- kf :
-
forward reaction rate
- M:
-
molecular weight, kg/kg-mole
- N:
-
number of nodes
- NS :
-
number of species
- ni :
-
moles of species i
- p:
-
static pressure, n/m2
- q:
-
heat flux, J/m2-s
- R:
-
steady-state residual; gas constant, J/kg-K
- Ro :
-
universal gas constant, J/kg-mole-K
- Ro′:
-
universal gas constant, cm3-atm/gm-mole-K
- T:
-
static temperature, K
- t:
-
time, s
- Δt:
-
time step, s
- →u:
-
dependent variable vector
- u:
-
streamwise velocity, m/s
- v:
-
transverse velocity, m/s
- ≈vi :
-
diffusion velocity of species i, m/s
- ≈ui :
-
streamwise diffusion velocity of species i, m/s
- ≈vi :
-
transverse diffusion velocity of species i, m/s
- wi :
-
species production rate of species i, kg/m3-s
- x:
-
streamwise spatial variable, m
- y:
-
transverse spatial variable, m
- Δx:
-
streamwise spatial step size, m
- Δy:
-
transverse spatial step size, m
- ζ:
-
computational streamwise coordinate
- η:
-
computational transverse coordinate
- μ:
-
laminar viscosity, kg/m-s
- λ:
-
second coefficient of viscosity, kg/m-s
- ϱ:
-
densty, kg/m3
- σ:
-
normal stress, N/m2
- Ï„:
-
shear stress, N/m2 Subscripts
- e:
-
edge value
- i,j:
-
species indices
- R:
-
reactions, reference value s species
- −:
-
mass weighted value, mean value
- ′:
-
fluctuating quantity
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© 1989 Springer-Verlag
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Drummond, J.P., Mukunda, H.S. (1989). A numerical study of mixing enhancement in supersonic reacting flow fields. In: Dervieux, A., Larrouturou, B. (eds) Numerical Combustion. Lecture Notes in Physics, vol 351. Springer, Berlin, Heidelberg. https://doi.org/10.1007/3-540-51968-8_75
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DOI: https://doi.org/10.1007/3-540-51968-8_75
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