Numerical Simulation of Three-Dimensional Reacting Flow in A Model Supersonic Combustor

Abstract

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

Nonlinear characteristics and detection of combustion modes for a hydrocarbon fueled scramjet

“…And the above flow Eqs. (1) and (2) are solved by using the built-in integration capacity of MATLAB. So the Mach number and total temperature distributions are attained.…”

“…A single-step global reaction model expressed as Eq. (4) is used for the evaluation of heat releasing of the equilibrium reaction assumption [1]:…”

“…Given the broad range of aero-thermodynamic conditions experiences during hypersonic flight [1,2], the supersonic combustion ramjet (scramjet) would operate under different combustion modes [4]. The transition between ramjet mode and scramjet mode is triggered through either changing flight Mach number, or control of the heat release due to combustion at a fixed Mach number ( [3]).…”

Specific features of ignition and flameholding of hydrocarbon fuels in high-speed flow

“…The comparative results indicate that the fuel injection con¦guration with opposing injector pairs located in the cavity, on the step, and the ramp are the most e©cient, resulting in 73 percent combustion e©ciency [30]. Details of the §ow ¦eld inside the combustor as well as variation of mixing e©ciency, combustion e©ciency, and total pressure loss along the combustor length are presented and discussed in [28].…”

“…Di¨erent arrangements were compared in terms of species mixing e©ciency and overall combustion optimization. The numerical approach is based on solving the full three-dimensional (3D) Navier Stokes equations supplemented with combustion models of di¨erent complexity with di¨erent chemical reactions and chemical species [28]. They could include a rate-controlling kinetic mechanism for combustion of di¨erent fuels in air.…”