LES of Enhanced Mixing and Combustion by Angled Fuel Injection Induced Streamwise Vortices in a Model Strut Supersonic Chamber

摘要

Large-eddy simulation (LES) of hydrogen-air combustion in a supersonic model combustor with a wedge-shaped strut based flame holder is carried out. Hydrogen is parallel injected into the air stream with sonic speed through several equally spaced holes located at the base of the strut. The subgrid-scale (SGS) turbulence stress tensor is closed via the Dynamic Smagorinsky-Lilly model, chemical source terms are modelled by a finite rate chemistry model, and a two-step reduced hydrogen combustion kinetic mechanism is adopted. Numerical predictions on the aerodynamic parameters and turbulent characteristics from the LES show consistent agreement with experimental data reported in literature. However due to the extremely short residence time of the injected hydrogen, sufficient mixing is hard to achieve. To enhance fuel-air mixing with lower penalty on performance, an alternative angled hydrogen injection scheme is proposed and studied by LES in this paper. Comparisons with conventional parallel injection showed that improved hydrogen-air mixing is achieved by the streamwise vortices induced by the injected fuel, and better combustion is realized.