基于LES的压气机叶栅通道非定常流动结构研究

为了进一步理解压气机叶栅通道内的非定常流动结构，采用大涡模拟(LES)方法研究了来流附面层厚度和稠度变化对叶栅通道内涡系结构及总压损失系数的影响。研究表明：来流附面层增厚将导致端壁处流体的轴向动能降低，使得马蹄涡压力面分支更早地流向相邻叶片吸力面；来流附面层越厚，通道涡在叶栅尾缘沿展向抬升的高度越高，角区分离的范围也越大；叶栅的总压损失随附面层增厚而增加，附面层损失增加显著，二次流损失有所增大；稠度较低时叶栅吸力面表面存在分离，会对通道涡及角区分离产生影响；稠度增大，横向压力梯度减小，叶栅流道的速度分布更均匀，通道涡的强度和尺度减小，角区分离的范围减小；稠度增大使叶表不再分离时，总压损失显著降低，但稠度继续增大会使气流与叶片表面的摩擦损失增加。

Investigation of Unsteady Flow Structure of Compressor Cascade Passage based on Large Eddy Simulation

In order to further understand the unsteady flow structure in compressor cascade passage, the effects of the thickness of incoming flow boundary layer and solidity changes on the vortex structure and the total pressure loss coefficient in cascade passage were studied by large eddy simulation (LES) method. The results show that the thickening of the incoming flow boundary layer leads to the decrease of the axial kinetic energy of the fluid at the endwall, which makes the pressure surface branch of the horseshoe vortex flow to the suction surface of the adjacent blade earlier; when the boundary layer of incoming flow is thicker, the height of passage vortex spanwise uplift along the trailing edge of cascade is higher, and the range of corner separation is larger; the total pressure loss of cascade increases with the thickening of boundary layer, especially the boundary layer loss and the secondary flow loss; when the solidity is low, the separation on the cascade suction surface will affect the passage vortex and the range of corner separation; with the increase of solidity, the transverse pressure gradient decreases, the velocity distribution of cascade passage is more uniform, the intensity and scale of passage vortex decrease, and the range of corner separation decreases; when the flow on the blade surface is no longer separated because of the increase of solidity, the total pressure loss is significantly reduced, but the friction loss between the air flow and the blade surface will increase with the increase of solidity.