Effects of the squealer winglet structures on the heat transfer characteristics and aerodynamic performance of turbine blade tip

The heat transfer characteristics and aerodynamic performance of three different squealer winglet structures based on GE-E3 turbine rotor squealer tip are numerically investigated, which is compared with the conventional squealer tip. The Reynolds-Averaged Navier-Stokes (RANS) solutions and standard k-omega turbulence model are solved to analyze the aerothermal performance of rotor tip with different squealer winglet structures. The numerical method is verified with experimental data. The numerical results show that the area-averaged heat transfer coefficient of squealer winglet structure at the pressure side, suction side and both the pressure and suction side are respectively reduced by 12.2%, 17.1% and 19.8% compared to the conventional squealer tip. The squealer winglet structure on the blade tip mostly influence the flow structures inside the cavity with the decreased strength of the pressure side corner vortex and the scraping vortex, which reduce the heat transfer coefficient and the leakage flow rate of the blade tip. The squealer winglet structure at the pressure side is found to increase the total pressure loss coefficient of the rotor blade by 8.5% in contrast to the conventional squealer tip. However, the squealer winglet structure at the suction side and both sides effectively reduce the total pressure loss coefficient by 8.5% and 2.5% respectively. The results reveal that squealer winglet structure at the suction side has the tradeoff of the heat transfer characteristics and aerodynamic performance among four different turbine rotor squealer tip profiles. (C) 2019 Elsevier Ltd. All rights reserved.