Analysis of Interaction between Leakage Flow and Upstream Wake by Proper Orthogonal Decomposition Applied

The turbine blade generally works in severe aerodynamic environments such as high temperature and high pressure. Various forms of secondary flow, unsteady potential flow, periodic wake in the blade passage, and strong interactions among these flow structures affect the efficiency of the turbine seriously. This paper performs a numerical simulation of the T106 cascade to investigate the flow characteristics and performance under the interaction between upstream wake and leakage flow. The cascade flow with and without upstream wake are decomposed by proper orthogonal decomposition, and the mode characteristics of leakage flow and wake are obtained. The results indicate that periodic wake can significantly reduce the energy loss in the channel and tip leakage flow has a greater impact in the region near the shroud plane. According to the proper orthogonal decomposition, the second to seventh modes account for 96.14% of the total energy except for the time-averaged mode. The second mode is identified as the wake mode and leakage flow can significantly increase vorticity in the tip region. The harmonics of the wake mode are greatly affected by leakage flow, especially at the trailing edge region.