Numerical Study of Supersonic Jet Characteristics of Underwater Solid Rocket Engine

Abstract

The structure of the rocket supersonic jet changes periodically when the solid rocket engines are ignited underwater. To investigate the flowfield structure and thrust characteristics of underwater gas jets emanating from solid rocket engines, this study establishes a numerical model for the multiphase flow of underwater jets based on the volume of fluid and realizable k-ε models. The effectiveness of the model is validated through comparison with experimental data. Subsequently, numerical simulations of tail jets from solid rocket engines are conducted at different water depths. The results indicate that during the underwater operation of solid rocket engines, the tail jet undergoes periodic processes such as expansion, constriction, rupture, and recoil. At larger depths, the environmental pressure exerts a more significant effect on the gas jet, thus resulting in a slower axial development of gas bubbles but more significant periodic evolution processes. Unlike the case in air, the thrust of solid rocket engines oscillates significantly when ignited underwater. In deeper water environments, the engine thrust presents a smaller oscillation amplitude. The findings of this study provide a theoretical basis for the design of solid rocket engines ignited underwater.