平面叶栅流场非定常特性分析

为了分析平面叶栅流场的非定常流动特性，采用延迟分离涡模拟方法(DDES) 对某亚声速叶栅流场进行数值计算。为了保证计算准确，首先进行了最优网格选择、物理时间步长无关性验证；并与RANS-SA计算结果、实验结果进行对比。DDES方法计算结果表明，随着攻角的增大，尾缘涡会逐渐由细长型转变为结构整齐，频率单一的对涡结构，当攻角继续增大，对涡结构变得越来越不整齐。当攻角增大到吸力面出现大分离时，对涡结构消失，脱落涡表现出很强的随机性，吸力面分离涡在向下游传播的同时向周向传播，对相邻叶片的涡量分布产生影响。在大攻角工况时，进口马赫数的变化对于吸力面分离涡，尾缘涡都产生非常大的影响。

Analysis of Unsteady characteristics of planar cascade flow field

In order to analyze the unsteady flow characteristics of a plane cascade flow field, a subsonic cascade flow field was numerically calculated by using delayed detached eddy simulation (DDES). In order to ensure the accuracy of calculation, the optimal mesh selection and physical time step independence are verified first. The results were compared with RANS-SA and experimental results. The results of the DDES method show that with the increase of the Angle of attack, trailing edge vortices gradually change from slender type to pair vortices with neat structure and single frequency. When the Angle of attack continues to increase, the vortex structure becomes more and more irregular. When the Angle of attack increases to a large separation on the suction surface, the vortex structure disappears and the detached vortex shows a strong randomness. The separation vortex on the suction surface propagates in the downstream direction as well as in the circumferential direction, which affects the vorticity distribution of adjacent blades. In the case of high Angle of attack, the change of inlet Mach number has a great influence on suction surface separation vortex and trailing edge vortex.