Influence of unsteady wake with trailing edge coolant ejection on turbine blade film cooling

Abstract

Detailed film cooling effectiveness distributions along a modeled turbine rotor blade under combined effects of upstream trailing edge unsteady wake with coolant ejection are presented using the pressure sensitive paint (PSP) mass transfer analogy method. The experiment is conducted in a low speed wind tunnel facility with a five blade linear cascade. The exit Reynolds number based on the axial chord is 370,000.Unsteady wakes and trailing edge coolant jets are produced by a spoked wheel-type wake generator with hollow rods equipped with several coolant ejections from holes. The coolant-to-mainstream density ratios for both blade and trailing edge coolant ejection range from 1.5 to 2.0 for simulatingr ealistic engine conditions. Blade blowing ratios studied are 0.5 and 1.0 on Suction surface and 1.0 and 2.0 on Pressure surface. Trailing edge jet blowing ratio and Strouhal number are 1.0 and 0.12, respectively. Results show the unsteady wake reduces overall film cooling effectiveness. However, the unsteady wake with trailing edge coolant ejection enhances overall effectiveness. Results also show that the overall filming cooling effectiveness increases by using heavier coolant for trailing edge ejection as well as for blade surface film cooling. Copyright © 2011 by ASME.