Effect of unsteady passing wake on the aerodynamic and heat transfer performance of the turbine blade squealer tip

By solving the Unsteady Reynolds-averaged Navier-Stokes equations and standard k-ω turbulence model, effect of unsteady passing wake on squealer tip heat transfer performance for a gas turbine stage with different rotating speed is numerically investigated. The results of turbulence model validation are in good agreement with the experimental data. The grid independence verification is also satisfied. The results indicate that the tip area-averaged heat transfer coefficient fluctuates periodically with time, and a “platform stage” is existed within the heat transfer curve from trough to peak. The heat transfer curve is divided into two independent phases by the “platform stage”. In the first phase, the heat transfer variation is concentrated in the tip front part, and the average heat transfer coefficient at this region increases by 3.4%. In the second phase, the variation of heat transfer in the tip rear part is obvious, and the average heat transfer coefficient of this region increases by 5.1%. Compared with the first and second phases, the heat transfer coefficient curve in the third phase shows the characteristics of uniform decline. The existence of the “platform stage” is closely related to the blade rotating speed. The “platform stage” will disappear as the blade rotating speed deviates from the standard condition.