Measurement and Modelling of Blade Tip Cooling in Gas Turbines

Blade tip cooling effectiveness simulations and measurements are reported. Measurements of metal blade surface temperature distributions were obtained in the laboratory using temperature sensitive paint technique, TSP, for mainstream Reynolds number, Re_M = 200,000, and cooling Reynolds number, Re_C = 10,000. The blade tip region consists of a cavity with thin walls on pressure and suction sides known as squealer rim. TSP technique is used to investigate the temperature demonstrating its applicability as cooling effectiveness measurement method on a blade tip region. Several film cooling holes placed along the airfoil camber line discharge coolant and spread over the tip cavity. Besides, conjugate cooling flow was numerically simulated, considering blade metal and mainstream contact under the effects of leakage through blade tip clearance using a finite volume program, Fluent, with good agreement between data and numerical results. Cooling effectiveness is investigated as function of blowing ratio and tip clearance.