Film Cooling Performance of the Moving Pintle in a Thrust-Controlled Solid Rocket Motor

To push the specific impulse and power output of the thrust-controlled solid rocket motor (TCSRM) even higher, the solid-propellant flame temperature is driven to 3000–3600 K. That level of thermal assault subjects the pintle to extreme heat flux and aggressive erosion, a combination that directly undercuts motor reliability. An effective cooling strategy for the pintle is therefore mandatory. Here, a film-cooling scheme is deployed for thermal protection of the pintle, and a comprehensive study on the transient aero-thermal characteristics of pintle film cooling is carried out to demonstrate how it outperforms the uncooled baseline in extending pintle survival and to reveal the effects of the blowing ratio and pintle moving speed on the performance. The results indicate that the film cooling contributes to improving the pintle cooling performance. As pintle velocity increases, the absolute velocity component of the coolant jet parallel to the mainstream velocity decreases. This causes the relative angle between the coolant jet and mainstream to increase, leading to a stronger interaction between the coolant jet and mainstream. Accordingly, except under low-blowing-ratio conditions, the time-averaged film-cooling effectiveness declines as the pintle velocity increases. Moreover, there is an optimum blowing ratio to achieve the highest time-averaged film-cooling effectiveness.