Numerical investigations on the unsteady leakage flow and heat transfer characteristics of the turbine blade squealer tip

Abstract

The unsteady leakage flow and heat transfer characteristics of the turbine blade squealer tip was numerically investigated using three-dimensional Unsteady Reynolds-Averaged Naiver-Stokes (URANS) and standard k-ω turbulence model. The numerical simulated heat transfer coefficients of the turbine blade tip were well agreement with the experimental data. The accuracy of the numerical method was validated. The steady and unsteady leakage flow and heat transfer coefficient of the turbine blade squealer tip with and without film cooling was conducted. The unsteady leakage flow and heat transfer characteristics of the turbine blade squealer tip with film cooling design at three different blow ratios was numerically investigated. The obtained results show that the corner vortex and scraping vortex near the pressure side shows periodic fluctuation along the separation line of the leakage flow under the function of the pressure difference between the suction and pressure side of the blade tip, as well as the upstream vane unsteady wake flow. This unsteady flow behavior results in the fluctuation of the high heat transfer coefficients at the blade tip. The film cooling design along the camber line can effectively reduce the thermal load of the turbine blade squealer tip by comparison to without film cooling case. The time-averaged heat transfer coefficients of the turbine blade squealer tip reduce 9.0%, 12.4% and 13.2% at blowing ratio of .0.5, 1.0 and 1.5 comparison to without film cooling design in respective. The present work can provide the reference of the film cooling design for the turbine blade squealer tip.