Computational Simulations of the Effect of Backstep Height on Nonpremixed Combustion Instability

摘要: Detailed computational simulations are used to compare the effect of backstep height on stability characteristics an axisymmetric dump combustor fed by separate fuel and oxidizer streams. Companion experiments demonstrate a dramatic increase in amplitude pressure oscillations for smaller due combustion instability. The goal present is ascertain whether computations can predict instability this configuration degree which they replicate experimental trend. Two different oxidizer-inlet boundary conditions were used: subsonic inlet choked inlet. Both predicted stronger backstep, although disturbances uniform case decayed relatively low levels. choked-inlet sustained but still somewhat than experiment. suggest arises because wall/vortex impingement smaller-step-height combustor. instantaneous heat release more strongly phase simulations, resulting larger Rayleigh indices. Power spectral density results likewise show peaks step. sensitivity upstream suggests that care should be taken designing both experiments.