Effect of upstream wake on flow characteristics of tip leakage at squealer tip with large-scale depth

The squealer tip is a common configuration used to enhance the aerothermal performance of the turbine. However, in the complex working environment of an aircraft engine, the scale influence of cavity depth interacts with rotational factor of the blade, and simultaneously superimposes the periodic sweeping formed by the upstream wake, causing complicated coupling characteristics of the flow in the cascade channel and tip clearance. This paper ‌concentrates on the goal of suppressing clearance leakage. Regarding the squealer tip, it conducts a study on the transient aerodynamic features‌ of leakage flow. Firstly, clarify the mechanism of the influence of cavity scales on leakage flow; next, for the cavity with large-scale depth, consider the effect of upstream wake on the flow inside the clearance, illustrate mechanism of upstream wake's effect on vortex system and mixing loss of clearance leakage, and analyze transient characteristics of leakage flow under the influence of upstream wake. In the study, it was found that the transport effect can effectively reduce the flow direction vorticity of leakage vortex. Under influence of the upstream wake, the relative leakage and flow loss decreased by 18.22% and 3.97%, respectively. The periodic sweeping of the upstream wake causes periodic fluctuations in the leakage amount and entropy increase loss.