固体发动机人工脱粘的二维实验与数值模拟

2-D experimental and numerical simulation of SRM stress-relief flap

针对固体火箭发动机前封头人工脱粘缝隙,设计了二维实验装置,用来模拟发动机点火过程中前封头人工脱粘位置受到点火冲击后的应力-应变情况。同时,采用流固耦合的数值方法,对比计算了实验工况,计算得到人工脱粘根部的应力-应变与实验吻合很好。通过数值研究发现,点火初期燃气对人工脱粘部位的冲击,会引起缝隙内部的压强振荡及装药表面的振动,其幅值取决于脱粘缝隙内的压强传播情况,点火后期振荡趋于消失。人工脱粘的装药表面应力与燃烧室压强基本一致,在尖端出现应力集中,且对于固定形式的人工脱粘,其增大幅值基本固定,与燃烧室压强无关。人工脱粘向壳体圆柱段的延伸,可能会减小应力集中的幅值。人工脱粘的缝隙宽度对脱粘部位的影响很小。

A two dimentional test model was designed to simulate the behavior of stress-relief flap region at SRM forward dome when ignition.And CFD method was used to simulate the corresponding test.The numerical results agree well with the stress measured in tests.Numerical and experimental research show that the hot gas impacts into the gap of stress-relief flap at the beginning of ignition and results in the pressure oscillation and grain surface vibration.These oscillation and vibration tend to disappear after ignition.The stress on the grain surface at stress-relief flap gap nearly equals to and varies with the pressure in the gap,but at the tip of the gap,there is stress accumulation.For fixed geometry of grain surface,the amplification of stress value at the gap tip to combustor pressure is also nearly fixed and independent of the combustor pressure value.The length of stress-relief flap affects the value of stress accumulation at the tip,longer debond may reduce it.The width of the stress-relief flap gap has little affect on the behavior of stress-relief flap region,both on the flowfield and the stress of grain surface.