Variable Fuel Grains Burn Velocities to Reduce Solid-Rocket-Motor Pressure Oscillations

Abstract

Large solid rocket motors are subjected to pressure oscillations for which the origin lies in the coupling between hydrodynamic instabilities and the first longitudinal acoustic modes of the combustion chamber. Static firing tests using two propellant grains in the combustion chamber have been performed. The pressure oscillation amplitude can be strongly modified by varying the burn velocity ratio between the two solid fuel grains. The pressure oscillations are significantly reduced when increasing the burn velocity of the upstream grain and are higher in the opposite case.