Linear Acoustic Analysis of Main Combustion Chamber of an Oxidizer-Rich Staged Combustion Engine

Abstract

A comprehensive linear acoustic analysis of the main combustion chamber of an oxidizer-rich staged combustion engine is presented. The theoretical basis is an acoustic wave equation derived from the conservation equations that characterize unsteady flow motions in the chamber. The physical model mimics the RD-170 main combustion chamber and includes all the geometric details, including the upstream flow distributor, oxidizer plenum, injector assembly, and main chamber. Damping effects associated with the flow distributor plate and injectors are accounted for by means of impedance boundary conditions. Acoustic communication between the main chamber and oxidizer manifold via the injector assembly is found to be significant. Acoustic waves excited in the main chamber propagate upstream and interact with the oxidizer dome, where they are partially damped by the flow distributor. The influence of baffle injectors on the chamber acoustic behavior is also studied. It is found that the largest contributor to damping is increased transport of acoustic energy out of the domain due to advective mean flow effects.