Computation of Acoustic Oscillations and Combustion Stability in a Rocket Engine with Combined Hub/Blade Baffles

Abstract

High-frequency combustion instability in liquid propellant rocket engines, a coupling between the acoustics of the combustion chamber and the combustion process, remains a problem of significant interest. In this paper we analyze the combustion stability of a rocket combustion chamber with combined hub and blade baffles. A methodology for determining the combustion stability was developed using a velocity potential formulation with an eigenfunction expansion and a combustion volume matching technique. The analytical results are consistent with previously stability computations and acoustic and hot fire test data. The results in the paper indicate that there are optimal locations and lengths for radially and circumferentially oriented baffle blades. The optimal locations are due to the location of velocity antinodes. The optimal lengths are due to a transition incorporating longitudinal wave modes as the baffle length increases.