When the laminar-to-turbulent transition occurs close to the blade trailing edge, the periodic passage of shear layer roll-up vortices over the trailing edge would influence the unsteady behavior of the blade wake. In this study, time-resolved Particle Image Velocimetry (PIV) measurements were performed, to investigate the unsteady behavior of blade wake taking account of upstream shear layer instability on the suction side and the associated turbulence production mechanism. The suction side of the wake shows slower velocity recovery in comparison with the pressure side of the wake. The Proper Orthogonal Decomposition (POD) eigenvectors were used to reconstruct the phase averaged flow field of the wake instability. In the deterministic process of the wake instability, the laminar separation vortex shedding mainly intensifies the momentum transport along the mainstream direction in the suction side of the wake. The wake instability, the Kelvin–Helmholtz instability, and the finer scales flow structures were isolated, and each of their contributions to the total turbulence production was quantified. The former two instabilities contribute comparable portions (each approximately accounts for 40%) to the overall flow loss. The reduced-order model with the first ten modes is able to capture the dominant flow instability.

当层流到湍流的过渡在叶片后缘附近发生时，剪切层上的涡旋在叶片后缘上的周期性通过会影响叶片尾流的不稳定状态。在这项研究中，进行了时间分辨粒子图像测速（PIV）测量，以研究考虑到吸力侧上游剪切层的不稳定性和相关湍流产生机理的叶片尾流的非稳态行为。与尾流的压力侧相比，尾流的吸力侧显示出较慢的速度恢复。适当的正交分解（POD）特征向量用于重建尾流不稳定性的相位平均流场。在唤醒不稳定性的确定性过程中，层流分离涡脱落主要增强了尾流吸力侧沿主流方向的动量传递。分离了尾流不稳定性，开尔文-亥姆霍兹不稳定性以及更细尺度的流动结构，并量化了它们对总湍流产生的贡献。前两个不稳定因素造成了总流量损失的可比部分（每个约占40％）。具有前十个模式的降阶模型能够捕获主要的流不稳定性。前两个不稳定因素造成了总流量损失的可比部分（每个约占40％）。具有前十个模式的降阶模型能够捕获主要的流不稳定性。前两个不稳定因素造成了总流量损失的可比部分（每个约占40％）。具有前十个模式的降阶模型能够捕获主要的流不稳定性。