In this paper, transient phenomenon during start up process of a pump fed liquid rocket engine is investigated through numerical simulation. The engine studied in this work is designed such that engine systems are not wetted with propellant until the engine is commanded to start. This is achieved by positioning the valves for propellant admission at the interface of test stand/flight stage and the engine. To evaluate engine performance during start transient for such systems, unsteady flow simulation was conducted using Method of Characteristics and equations for priming. The same has been reported in this work. The results indicated a brief period of abrupt pressure rise at pump upstream after opening of the propellant admission valves, during the process of priming of engine systems at valve downstream. The peak pressure obtained was significantly higher than the propellant tank pressure as well as the steady state pump suction pressure. The transitory pressure rise was found to occur due to flow resistance at impeller inlet caused by formation of a forced vortex for orienting the flow through impeller blades during off design transient regime. The maximum pressure at pump upstream, as computed from start transient simulation, was used as a design input for pump inlet feed lines. The engine was realized and subsequently qualified in a ground test facility. Hot test data obtained for pressure and flow rate during transient regime were found to be in good agreement with the simulation results.

本文通过数值模拟研究了泵送式液体火箭发动机启动过程中的瞬态现象。在这项工作中研究的发动机的设计使得发动机系统不会被推进剂弄湿，直到发动机被命令启动。这是通过将用于推进剂进入的阀门定位在试验台/飞行台和发动机的接口处来实现的。为了评估此类系统在启动瞬态期间的发动机性能，使用特性方法和启动方程进行了非稳态流动模拟。在这项工作中也有同样的报道。结果表明，在推进剂进气阀打开后，在阀门下游的发动机系统启动过程中，泵上游的压力会出现短暂的突然上升。获得的峰值压力明显高于推进剂罐压力以及稳态泵吸入压力。瞬态压力升高是由于在非设计瞬态状态下形成强制涡流而导致的叶轮入口处的流动阻力而发生的，该涡流用于定向通过叶轮叶片的流动。从启动瞬态模拟计算得出的泵上游的最大压力用作泵入口进料管线的设计输入。该发动机已实现并随后在地面测试设施中合格。发现在瞬态期间获得的压力和流量的热测试数据与模拟结果非常吻合。瞬态压力升高是由于在非设计瞬态状态下形成强制涡流而导致的叶轮入口处的流动阻力而发生的，该涡流用于定向通过叶轮叶片的流动。从启动瞬态模拟计算得出的泵上游的最大压力用作泵入口进料管线的设计输入。该发动机已实现并随后在地面测试设施中合格。发现在瞬态期间获得的压力和流量的热测试数据与模拟结果非常吻合。瞬态压力升高是由于在非设计瞬态状态下形成强制涡流而导致的叶轮入口处的流动阻力而发生的，该涡流用于定向通过叶轮叶片的流动。从启动瞬态模拟计算得出的泵上游的最大压力用作泵入口进料管线的设计输入。该发动机已实现并随后在地面测试设施中合格。发现在瞬态期间获得的压力和流量的热测试数据与模拟结果非常吻合。该发动机已实现并随后在地面测试设施中合格。发现在瞬态期间获得的压力和流量的热测试数据与模拟结果非常吻合。该发动机已实现并随后在地面测试设施中合格。发现在瞬态期间获得的压力和流量的热测试数据与模拟结果非常吻合。