液体火箭发动机关机水击特性仿真

关机水击是引起液体火箭发动机及其试验台故障的常见现象之一。为获得关机水击的主要影响规律,采用一维有限体积法建立了发动机关机水击仿真模型,通过地面试验验证了模型的正确性。针对发动机常见设计变量,开展仿真研究,结果表明:水击增量与推进剂流量、流速成正比;管路足够长时,水击增量与其长度无关,但管路过短时,管路越短,水击增量越小;局部流阻靠近贮箱有利于降低水击,加快收敛;阀门作动时间小于半个水击周期时,水击增量等于完全水击值,否则,阀门作动时间越长,水击值越小;推进剂内注入少量气体,能明显抑制关机水击。

Simulation on water hammer during liquid rocket engine shutdown

Water hammer during shutdown is one of the common phenomena that cause liquid rocket engine or its test bed to fail.To study the characteristics of water hammerduring liquid rocket engine shutdown,simulation models were built based on one-dimensional finite element and the correctness of these models were verified by ground test.On this basis,the influences of common design variables were studied by simulation.The results show that the increment of water hammer is proportional to the flow rate and velocity of propellant.When the pipe is long enough the increment of water hammer is independent of its length,otherwise the shorter the pipe is,the smaller the increment is.The closer the local flow resistance is to the tank,the more favorable it is to reduce water hammer increment and accelerate its convergence.When the valve movement time is less than half of the water hammer cycle,the water hammer increment is equal to complete water hammer value,otherwise the shorter the valve movement time is,the smaller the water hammer will be.The water hammer will be obviously inhibited,while a small amount of gas is injected into the propellant.