Investigation of Leakage Flow and Heat Transfer in a Gas Turbine Blade Tip With Emphasis on the Effect of Rotation

Numerical analysis was applied to investigate the effect of rotation on the blade tip leakage flow and heat transfer. Flows around both flat and squealer tips at the first stage rotor blade of GE $E3$ high-pressure turbine were studied. The tip gap and squealer groove depth were specified as 1% and 2% of the blade height, respectively. The heat transfer coefficient on the tip surface was obtained by using different turbulence models and compared with the experimental data. The grid independence study was also carried out by using the Richardson extrapolation method. The effect of the blade rotation was studied in the following cases: (1) the blade domain is rotating and the shroud is stationary; (2) the blade domain is stationary and the shroud is rotating; and (3) both blade domain and shroud are stationary. In this approach, the effects of the relative motion of the endwall, the centrifugal force, and the Coriolis force can be investigated, respectively. By comparing the results of the three cases discussed, it is concluded that the main effect of the rotation on the tip leakage flow and heat transfer resulted from the relative motion of the shroud, especially for the squealer tip blade.