Effects of Squealer Geometry of Turbine Blade Tip on the Tip-Leakage Flow and Loss

The effective control of the tip-leakage flow and loss is of great significance to improve the aerodynamic performance of the turbine. In this paper, the evolution mechanism of tip-leakage flow in a transonic high pressure turbine with a squealer tip is investigated with numerical simulation methods. The impacts of squealer geometric, such as the inclined pressure side rim and squealer rim width, on the vortex structure in the gap and tip-leakage loss are discussed. The results show that the scraping vortex inside the cavity plays the role of aero-labyrinth seal, and forms interlocking sealing labyrinth structure with the rims on both sides, which has an effective sealing effect on the tip-leakage flow. The inclined pressure side squealer rim inhibits the development of the pressure side squealer corner vortex, which is beneficial to expand the influence range of the scraping vortex and enhance the sealing effect on the tip-leakage flow. The increase of the suction side squealer rim width reduces the effective flow area at the gap exit, which is conducive to reduction of the tip-leakage flow rate and tip-leakage loss. However, the increase of the pressure side squealer rim width strengthens the pressure side squealer corner vortex and limits the development space of the scraping vortex, causing the adverse effects on the control of tip-leakage flow.