Hybrid Reynolds-Averaged and Large-Eddy Simulations of a Supersonic Cavity Flameholder

Abstract

Simulation results are presented for non-reacting flow within a supersonic cavity flameholder. The freestream is air at Mach 2. A case is simulated with no fuel injection, and two cases are simulated with different rates of ethylene fuel injected through holes located on the back face of the cavity. The simulations correspond to a series of experiments for which particle image velocimetry measurements of two velocity components were made within the cavity. Reynolds-averaged Navier-Stokes simulations are used to examine the influence of the finite-width, low-angled slot used to seed the flow for the particle image velocimetry. The simulations indicate that the seeder has little influence on the flow within the cavity, allowing for the seeder to be neglected in the remainder of the simulations. The flow within the cavity is simulated using steady-state Reynolds-averaged Navier-Stokes simulations, as well as unsteady hybrid Reynolds-averaged Navier-Stokes and large-eddy simulations. A thorough grid resolution study is presented in which the resolution required to resolve the flow within the cavity is determined. The results of the simulations on the final grids are compared to the velocity measurements from the experiments and the hybrid Reynolds-averaged Navier-Stokes and large-eddy simulation results are found to provide improved agreement with certain aspects of the flow. The simulation results are then used to investigate the mixing within the cavity, which was not measured in the experiments. The mixing information from the simulations provides further insight into the physics of the cavity flameholder flowfield.