Low-Frequency Combustion Instability Induced by the Combustion Time Lag of Liquid Oxidizer in Hybrid Rocket Motors

Abstract

This paper deals with a theoretical analysis of the low-frequency combustion instability induced by the combustion time lag of liquid oxidizer in small-scale hybrid rocket motors. We obtained the determined linear stability limit using the following parameters: the combustion time delay of liquid oxidizer, the residence time of a combustion chamber, injector pressure, chamber pressure, mass flux exponent, O/F, and the polytropic exponent of mixture gas in a combustion chamber. Kitagawa and Yuasa sometimes observed low-frequency oscillations, such as chugging, in their swirling-oxidizer-flow-type hybrid rocket engine. The obtained theoretical stability limit was compared with these experimental data.