Application of the vortex effects induced by the trailing wedge to enhance the mixing and combustion in the strut-based scramjet

Abstract

Fuel-air mixing is very critical to the development of a scramjet engine. In order to enhance the fuel-air mixing and combustion, this research introduces the trailing wedge to induce the vortex effects. It is studied in detail through numerical simulations which is verified by ground experiments. High enthalpy vitiated airflow is produced by a hydrogen-combustion heater to simulated Mach 5.0 flight condition. The inlet Mach number and stagnation temperature are 2.0 and 1231 K, respectively. The k-ω SST turbulence model simulated the turbulent stress effect is used to solve the three-dimensional Reynolds average reacting flow. A finite-rate/eddy-dissipation model combined with a simplified two-step kerosene reaction mechanism are utilized to model the turbulent combustion. The atomization and vaporization of the liquid fuel are simulated using the discrete phase mode. Cold flow condition is simulated to obtain the detailed fuel-air mixing process. The mixing performance is greatly enhanced by the introduction of the trailing wedge. The mixing efficiency is increased by 17.5%. The plume area and combustible area are also obviously expanded by the trailing wedge. The vorticity analysis indicates that the streamwise vortex induced by the trailing wedge has promoted the macro transport process which dominate the mixing process. The hot flow simulation results show that the combustion and heat release process is wholly enhanced by the trailing wedge. The total pressure loss in the combustor with trailing wedge is reduced by about 0.7% at the same time.