液氢绕回转体非定常空化的流动特性

为研究航空发动机内部低温燃料的非定常空化流动特性，采用大涡模拟(LES)对液氢绕回转体的非定常流动特性进行了分析。通过与实验结果的对比可知，所采用的数值计算方法能够有效地模拟液氢绕回转体流动的非定常过程。讨论了空化演化过程和旋涡动力特性，研究结果表明:空化的非定常演变过程大致可以分为3个阶段:附着空穴生长阶段、大尺度空泡发展阶段和小尺度空泡发展阶段，且反向射流是造成空穴不稳定及脱落的主要原因；探讨了空化与旋涡之间的交互作用，明确了空穴前端和尾端处的涡量源于旋涡伸长项，空穴内部涡量源于旋涡扩张项，空穴交界面、反向射流头部区域涡量源于斜压扭矩项。 

Unsteady cavitating flow of liquid hydrogenaround the ogive body

In order to investigate the unsteady cavitating flow characteristics of the cryogenic fluids in the aircraft engine, Zwart cavitation model and large eddy simulation (LES) turbulence model were used to simulate the unsteady cavitating flow of liquid hydrogen around an ogive body. The results showed that compared with the experiments, the unsteady cavitating flow of liquid hydrogen around the ogive body could be accurately simulated by the numerical calculation model. The cavitation evolution process was divided into three stages: the growth of attached cavity, the development of large-scale cavity and the development of small-scale cavity. The analysis of flow field showed that the re-retrant jet was the main cause of the cavitation shedding and instability. Besides, the interaction between cavitation and vorticity was also analyzed. The vortex streching, vortex dilation and baroclinic torque terms were contributed to cavitation structures of leading and trailing parts of cavity, inside the cavity and at the interface between the cavity with mainstream and head of the re-retrant flow, respectively.