Ignition Transient of Dual-Thrust Solid Propellant Rocket Motors - A Review

Abstract

This paper addresses the future design challenges associated with the development of high-performance dual-thrust solid propellant rockets, because of their large size, high volumetric loading density, high length-to-diameter ratio, and demanding thrust time trace shape requirements; after a close perusal of the earlier theoretical and experimental findings. We had observed and reported earlier that, at the subsonic inflow conditions, there is a possibility of the occurrence of internal flow choking in dual-thrust motors due to the formation of a fluid throat at the beginning of the transition region induced by area blockage caused by boundarylayer-displacement thickness. Through empirical techniques, increasing the upstream port area of the motor has often been proposed as one of the remedies for negating the internal flow choking and further eliminating the unusual ignition pressure spike often observed during the ignition transient of dual-thrust motors. Unfortunately, this reduces the propellant loading density and affects the high performance nature of the rocket motor due to the envelop restriction. The objective of this review is to verify the applicability of the existing concepts before embarking on the formulation of a new model and a code of solution for high performance solid propellant rockets with non-uniform port geometry.