Effect of clearance height on aerodynamic losses for flat and squealer tip geometries of gas turbine blade

A thorough 3d numerical study is performed to predict the flow field around a gas turbine rotor blade in cascade circumstances. Calculations are carried out for both flat and squealer blade tip geometries by means of solving Reynolds-averaged Navier-Stokes equations in conjunction with the k-ω two-equation turbulence model. For each geometry, three different tip gap-blade span ratios of 1%, 1.5% and 2.5% in contrast with 0% clearance are examined. By comparing the results, behavior of flow vortices and consequent loss coefficients at the downstream of the blade, around the gap region area have been elucidated. The squealer cases noticeably decreased the leakage ratio compared to the flat ones, however was not effective as much in reduction of the exit total loss particularly in small gap heights.