Simulation Research On Analogical Medium Test Of The Hydrogen Pump

The hydrogen pump of the LH₂/LOX rocket engine must be tested to obtain the performance.But the problems are cryogenic condition,dangerous,and expensive of Liquid H₂ for the test.It is necessary to find an analogical medium for LH₂.In hydraulic test,the test condition is far from operating condition of the LH₂ pump,because of water’s viscosity and density.So the analogical medium such as low temperature nitrogen should be used as its safer and cheaper,and nearly same of viscosity and density.So that,the hydrogen pumps of the small thrust engine,the medium thrust engine and the heavy thrust engine are researched.These results of flow field and external characteristics by CFD in LH₂ and low temperature nitrogen are compared to analysis the similarity.The similarity is affected by Reynolds number（Re）and compressibility.So the similarity conversion relation and medium selection method are put forward by considering Re.In view of the difficulties in calculating head rise of the pump,characteristic density and isentropic head rise are proposed to obtain external characteristics of the pump in compressible fluid.The ARK gas equation is used to describe compressible medium,the inlet conditions and operation conditions are put forward for the pump in analogical medium test.Comparing the result of CFD with test,show that,CFD result is good agreement with test result in LH₂ and low temperature nitrogen.So that,the CFD result of low temperature nitrogen is similarity with LH₂ test result.The shock wave may appear in the pump,as the flow velocity is close to the sound speed in compressible medium.Therefore,the limitation of the velocity in the pump is required.The low temperature nitrogen test result may reflect the flow field characteristic of the LH₂ pump.But the limitation of the accuracy is as shown that,the LH₂ pump of the small thrust engine is better,and the LH2 pump of the medium and heavy thrust engine are uncertain.