Response of propellant combustion to a turbulent acoustic boundary layer

Abstract

An analysis of the transitional and turbulent reactive acoustic boundary layer on a homogeneous, solid-propellant surface is conducted to investigate potential mechanisms of combustion instability. The theoretical approach utilizes a low Reynolds number turbulence closure model and a finite-difference solution procedure for an equation system of parabolic form. A new technique is developed for the condensed-phase thermal layer, in which the propellant space is mapped onto the gas space and efficiently solved using the same adaptive numerical grid. Results are obtained at an acoustic pressure node in the absence of a mean axial flow. The results indicate that acoustically induced transition can occur at relatively low acoustic pressure amplitudes, propellant response to harmonic axial velocity fluctuations is both rectified and displays a mean augmentation (D-C shift), and that nominal propellant combustion parameters lead to increasing susceptibility to acoustic transition at elevated mean pressures. As OQ Bg cp €« / H h h^ k ks L® n q R Reac Res Ret Ru r