The Effect of Resistance on Rocket Injector Acoustics

C. J. Morgan [1], S. R. Fischbach [1],
[1] Jacobs ESSSA Group, NASA Marshall Space Flight Center, Huntsville, AL, USA
Published in 2015

This study evaluates the effect of injector resistance on the mode shapes and complex eigenfrequencies of an injector/combustion chamber system by defining a high Mach-flow, potential flow form of the convective wave equation in the Coefficient Form PDE Mathematics interface. Background steady-state flow conditions are determined through a NASA Marshall Space Flight Center in-house fluid dynamics model and interpolated onto the COMSOL mesh. Two cases are investigated. For the low resistance case the injector/manifold boundary behaves as acoustically open, while for the high resistance case it behaves as acoustically closed. The knowledge gained through this model can be used during future design cycles to favorably shape the combustion chamber mode shape.