Numerical simulations of the three-dimensional reacting flow in a staged supersonic combustor (Mach 2.5) have been carried out. The combustor has a strut for the first stage and wall-mounted injectors for the second stage (S. Tomioka, A. Murakami, K. Kudo, and T. Mitani, "Combustion Tests of a Staged Supersonic Combustor with a Strut," Journal of Propulsion and Power, Vol. 17, No. 2, 2001, pp. 293-300). The Spalart-Allmaras model has been used for modeling turbulence and single-step finite-rate chemistry has been used for modeling the H 2 /Air kinetics. The grid has been refined to achieve average value for wall y + less than 20. The predicted static-pressure profile along the centerline of the combustor is compared with experimental data for different injection schemes. Details of the flowfield inside the combustor as well as variation of mixing efficiency, combustion efficiency, and total pressure loss along the length are presented and discussed. Nomenclature A= cross-sectional area of the combustor, m 2 m fuel,in = mass flow rate of fuel, kg/s P = static pressure, Pa P 0 = local stagnation pressure, Pa P 0,inlet = inlet stagnation pressure, Pa T = static temperature, K T 0 = local stagnation temperature, K T 0,inlet = inlet stagnation temperature, K u = velocity along the x direction, m/s α = local fuel mass fraction α s = stoichiometric fuel mass fraction γ = ratio of specific heats η c = combustion efficiency η m = mixing efficiency η t = total pressure loss ρ = mass density, kg/m 3 φ = local equivalence ratio

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A cross-sectional area k turbulent kinetic energy m fuel,in mass flow rate of fuel Ma Mach number P static pressure P 0 local stagnation pressure P 0,inlet inlet stagnation pressure T static temperature T 0 local stagnation temperature T 0,inlet inlet stagnation temperature u velocity along the x-direction Y i mass fraction of species iGreek symbols α local fuel mass fraction α s stoichiometric fuel mass fraction ε turbulent strain rate η c combustion efficiency ABSTRACTResults from numerical simulations of supersonic combustion of H 2 are presented. The combustor has a single stage fuel injection parallel to the main flow from the base of a wedge. The simulations have been performed using FLUENT. Realisable k-ε model has been used for modelling turbulence and single step finite rate chemistry has been used for modelling the H 2 -Air kinetics. All the numerical solutions have been obtained on grids with average value for wall y+ less than 40. Numerically predicted profiles of static pressure, axial velocity, turbulent kinetic energy and static temperature for both non-reacting as well as reacting flows are compared with the experimental data. The RANS calculations are able to predict the mean and fluctuating quantities reasonably well in most regions of the flow field. However, the single step kinetics predicts heat release much more rapid than what was seen in the experiments. Nonetheless, the overall pressure rise in the combustor due to combustion is predicted well. Also, the k-ε model is not able to predict the fluctuating quantities in the base region of the wedge where there is strong anisotropy in the presence of combustion.

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