Effect of Cutbacks on Tip Leakage Flow and Film-Cooling Effectiveness of a Turbine Blade Tip under Relative Moving Condition

抄録

Numerical investigations are conducted to study the tip leakage flow and cooling effectiveness on various film-cooled squealer tips. The effect of partial squealer rims on the leakage flow structure, tip leakage loss and tip film-cooling effectiveness is illustrated under four blowing ratios by considering the relative motion between the turbine blade and the stationary casing. Six cutback configurations of partial squealer rims, including three pressure-side trailing-edge cutbacks and three suction-side trailing-edge cutbacks with different cutback lengths, are considered in total. Two types of film-hole arrangements are used, both having the same film holes. In the first type, 13 film holes are arranged uniformly along the middle camber line (referred to as CL mode). In the second type, seven film holes are located in the vicinity of the leading-edge and the remainder of the film holes are arranged near the suction side in the mid-chord region (referred to as LE mode). It is found that the partial squealer with cutback near the trailing-edge produces larger tip leakage mass flow ratios than the full squealer, especially for the suction-side squealer cutback. However, the blade tips with a suction-side squealer cutback are conducive to reducing the tip leakage loss, especially for the partial squealer with a moderate cutback length. Furthermore, the suction-side squealer cutbacks can improve the tip film-cooling effectiveness at the trailing-edge of the blade to a great extent. It is also confirmed that the LE mode produces a more uniform and higher tip film-cooling effectiveness than the CL mode.