Study on cook-off behavior of HTPE propellant in solid rocket motor

Abstract

The work is devoted to research the thermal security problems of a solid rocket motor with ammonium perchlorate/hydroxyl polyether (AP/HTPE). For the star-charged rocket motor, the two-step global reaction is used to describe the cook-off process of AP/HTPE, with the natural convection inside motor considered. The 3D model is used to numerically predict cook-off behavior of rocket motor at three ambient temperatures. The effects of two heat transfer modes (heat conduction, natural convection) of nitrogen on the cook-off characteristics of the rocket motor are studied. The results show that different heat transfer modes in the cavity have a certain influence on the casing temperature at ignition, the ignition temperature of the propellant and the ignition delay period. The most prominent one is that the influence of convection on ignition delay is enormous in high temperature environment. For example, the error of ignition delay at 900 K and 1100 K is 26.08% and 15.52%. At the same time, the influence of convection on the shape of ignition area, the size of ignition point and the ignition temperature is also evident.