氦气驱动预压涡轮泵启动初期反流问题分析

用于某液体火箭发动启动动系统的气驱预压涡轮泵在起动初期出现了气体反流,导致预压泵呈夹气状态,对发动启动动过程控制不利。根据驱动试验系统原理,在MWorks平台中对驱动过程进行了仿真。对预压泵采用了Suter全特性表达式,对涡轮管路及排放路分别建立了描述排空与两相流动过程的简化数学模型。结果表明,导致反流的原因为涡轮入口及出口管路存在液相积存条件下,氦气驱动排空过程中导致气液两相流动状态下压降升高,使氦气通过结构间隙大量进入泵端。可通过调整结构间隙、减小排放路流阻等措施来降低反流对启动过程的影响。

Analysis on backflow problem during initial start-up process of helium-driven pre-pressurized turbopump

During the initial start-up process of the gas-driven pre-pressurized turbopump used in the start-up system of a liquid rocket engine,the gas backflow phenomenon occurred and it caused the pre-pressurized pump to be in the cavitation state,which was harmful to the control of engine start-up process.According to the principle of the driving test system,the driving process was simulated by the MWorks software.The Suter full-characteristic expression was adopted for the pre-pressurized pump.A simplified mathematical model was established to describe the emptying and two-phase flow processes for the turbine pipeline and the discharge pipeline.The results show that the backflow is caused by the liquid phase accumulation in the turbine pipeline,and the pressure drop of the two-phase flow is increased during the emptying process,so that a large amount of helium enters the pump end through the structural gap.The influence of backflow during the start-up process can be reduced by adjusting the structure gap or reducing the flow resistance of the discharge pipeline.