Comparative Evaluation Between Experiment and Simulation for a Transverse Instability

A transverse combustion instability study composed of experimental and hybrid Reynolds-averaged Navier–Stokes/large eddy simulation results is described. The study is focused on gas-centered swirl coaxial injector elements like those used in the main chambers of oxidizer-rich staged-combustion engines. Experimental results are obtained from a self-excited, multi-element, high-pressure model rocket combustor. The simulation uses a velocity forcing technique to match the frequency and amplitude of the pressure oscillations that are measured in the combustor. Chemiluminescence is used to indirectly measure heat release rate in the experimental investigation. Detailed comparisons between the predicted and measured pressure field and the predicted and measured heat release modes are made. Modal decomposition is used to systematically compare the heat release modes. Results show successful computational replication of the experimental unsteady environment through the use of the velocity forcing technique and the successful qualitative matching of experimental CH* emission with computational heat release rate.