A Computational Study of Ramjet, Scramjet and Dual-Mode Ramjet/Scramjet Combustion in a Combustor with a Cavity Flameholder

摘要

In this study we use Large Eddy Simulation (LES) to examine the flow, fuel-injection, mixing, self-ignition and turbulent combustion in a dual-mode ramjet/scramjet combustor with a cavity flameholder. The target case is the direct connect facility dual-mode ramjet/scramjet combustor studied experimentally by Micka & Driscoll in a series of publications, [10-15], under different operating conditions and using both hydrogen (H_2) and ethylene (C_2H_4) as fuels. Comparison with the experimental data is used to evaluate the predictive capabilities of the LES model and the reaction mechanisms, and to provide additional information about the flow, mixing and combustion physics in the combustor. Both the experimental data and the LES results predict different combustion behavior depending, primarily, on the value of the stagnation temperature, T_0; More specifically, for T_0≤1150 K, the flame is turbulent and highly unsteady, and anchor (on average) over the cavity (cavity stabilized combustion) whereas for T_0≥1350 K the flame is turbulent but steady, and anchor in the wake of the fuel jet (jet-wake stabilized combustion). For intermediate values of T_0, 1150