Study on the combustion characteristics of LOX/kerosene pintle injector based on the state of liquid oxygen

Pintle injector has strong application prospects in deep-throttling variable thrust rocket engines due to its excellent throttling and combustion performance. However, research on the combustion performance of cryogenic propellants in pintle injectors is still relatively scarce. This is particularly true when considering that under throttling conditions, the physical properties of cryogenic propellants are highly temperature-dependent, which can significantly alter the atomization and combustion performance of the pintle injector. This study presents a 50% throttling condition hot test on a liquid oxygen kerosene pintle engine, in which the liquid oxygen properties were altered by adjusting the pintle opening. The experimental results show that under the 50% throttling condition, the pintle injector can maintain combustion efficiency above 95%, with stable and rapid pressure buildup and no abnormal combustion phenomena such as instability. As the pintle opening increased, the amount of liquid oxygen vaporized inside the injector increased, the engine combustion efficiency decreased, and significant changes occurred in the engine's tail flame. Subsequently, a numerical simulation was performed to study the influence of partial vaporization of liquid oxygen inside the pintle injector on the spray and combustion process. This study explores the effect of the liquid oxygen injection state on the combustion performance of the pintle injector, providing scientific support for the application of cryogenic pintle injectors.