Regarding the evaluation of the solid rocket propellant response function to pressure coupling

Abstract

High frequency combustion instabilities imply a major risk for the solid rocket motor stable working and they are directly linked to the propellant response to chamber pressure coupling. This article discusses a laboratory testing method for the measurement and evaluation of the pressure coupled response for non-metalized propellants in a first stage. Experimental researches were done with an adequate setup, built and improved in our lab, able to evaluate the propellant response by interpreting the pressure oscillations damping in terms of propellant response. Our paper aims at defining a linearized one-dimensional flow study model to analyze the disturbed operation of the solid propellant rocket motors. Based on the applied model we can assert that the real part of propellant response is a function of the oscillations damping, acoustic energy in the motor chamber and various losses in the burning chamber. The imaginary part of propellant response mainly depends on the normalized pulsation, on the burning chamber gas column and on the pressure oscillations frequency. Our research purpose was obviously to minimize the risk of the combustion instabilities effects on the rocket motors working, by experimental investigations using jet modulating techniques and sustained by an interesting study model based on the perturbation method.