固体火箭发动机高空模拟试验的流场仿真

Numerical Simulation of Flow Field in High Altitude Simulation Test of Solid Rocket Motor

针对固体火箭发动机被动引射式高模试验,在发动机点火及熄火过程中存在的回火,给发动机喷管及对布置在高空舱内的测试装置和线路构成了严重威胁的问题。利用Navier-Stokes方程(N-S)和Spalart-Allmaras模型对发动机被动引射高空模拟试车全程进行流场瞬态仿真:对试验过程中发动机建压、稳压、减压及高空舱补气等阶段的流场结构进行仿真,同时对扩压器及高空舱内的流场进行仿真,分析高模试验各阶段的流场结构。结果显示:测点的实测数据与仿真曲线大致重合,只在补气的最初阶段略有差别,实测数据与仿真数据的整体吻合度较高。建压和减压过程,应采取绝热措施防止高温燃气对发动机,特别是喷管和后封头处破环,此外应对喷管外形面进行合理设计,以控制回火气体的分离点,有利于减小回火造成的影响。稳压段高空舱内流场结构稳定,不会对发动机造成影响。

By using Navier-Stokes equation and Spalart-Allmaras model,transient simulation of flow field is carried out for whole journey of test run of engine altitude simulation with passive ejecting.The flow field structures of various stages are simulated,such as engine pressure buildup,pressure stabilization,pressure reduction,and air injection of altitude chamber during experimental process.In the meantime,the flow field of diffuser and altitude chamber is simulated,then the flow field structure of each experimental stage is analyzed.The simulation results show that the measured data coincides with simulation curve approximately.Slight difference exists only in initial stage of air injection,which indicates that overall goodness of fit between measured data and simulation data is high.Thermal insulation should be taken to prevent damage of fuel gas with high temperature for engine,especially exhaust pipe and rear head during process of pressure buildup and reduction.Furthermore,shape face of exhaust pipe should be designed reasonably to control separation point of temper gas,which is beneficial for reducing influence caused by temper.Flow field structure of altitude chamber during pressure stabilization process is stable.It cannot influence the engine.