摘要

In the actual gas turbine system unsteadiness of the mainstream flow influences the heat transfer and surface pressure distribution on the blade. The unsteadiness on the turbine airfoil develops from four different sources: potential flow interactions, shock wave passage, wake passage and random free-stream turbulence from the combustion chamber. In order to simulate these conditions, experimental film cooling study with externally imposed pulsation is performed with the purpose of characterizing both the effects of turbine unsteadiness on film cooling (with the frequency ranges typical to actual turbine), and also to figure out the range of Strouhal number pulsation under various blowing conditions, which could possibly deliver better improvement in film cooling. Velocity measurements are realized with phase decomposition TR-PIV and temperature in the flow are resolved by using cold wire anemometry. Secondary flow is pulsed at St=0, 0.2, 0.3, 0.5 and studied blowing ratios are equal to M=0.65 and 1.