2D Navier-Stokes stability computations for solid rocket motors - Rotational, combustion and two-phase flow effects

Abstract

D Navier-Stokes stability computations are performed on a simple cylindrical port motor. The 2D results, in terms of motor frequency and damping, as well as in terms of full acoustic field, are compared to classical ID linear acoustic balance. The 2D computations are performed with models representing the propellant combustion response and two-phase flow behavior. The models are used separately and then together. The results show that the overall tendencies are correctly obtained over a large range of model parameter settings. Surprisingly it is found that the 2D results do not depend on the grid spatial resolution and that the details of the so-called acoustic boundary layer (ABL) need not to be resolved. This finding is also true for the two-phase flow damping. Analysis of the computed 2D acoustic field show that the ABL displacement effect is an effective damping source (even for an ABL penetrating into the core of the flow) and that an extra damping exists which is not incorporated into the classical acoustic balance.