Dynamic Hybrid Reynolds-Averaged Navier–Stokes/Large-Eddy Simulation of a Supersonic Cavity: Chemistry Effects

Abstract

A Mach 2 supersonic cavity flameholder is simulated using three hybrid Reynolds-averaged Navier–Stokes (RANS)/large-eddy simulation (LES) turbulence modeling approaches. Finite rate chemistry is included with an ignition-delay-optimized three-step ethylene mechanism. The models investigated include the Improved Delayed Detached Eddy Simulation (IDDES) model, with both steady and unsteady (turbulent) inflow conditions, as well as the dynamic hybrid RANS–LES (DHRL) model with steady inflow conditions. Results are interrogated to determine the effect of combustion on the flowfield within the cavity. Results between the different models are also compared with one another and to experimental data to highlight key differences between them. It is found that both the IDDES model with unsteady inflow (UIDDES) and the DHRL model show significantly better predictive performance than the IDDES model with steady inflow. Analysis of turbulence production mechanisms for each of the models provides insight into the reasons for this behavior. Interestingly, the DHRL model is capable of mitigating well-known weaknesses of traditional hybrid models in the region of RANS-to-LES transition without requiring the use of a more complex unsteady inlet boundary condition prescription.