Effect of coolant pulsation on film cooling performance on turbine vane

Combined with infrared thermography measurements, large eddy simulation was used to study the square-wave pulsating film cooling on turbine vane at the time-averaged blowing ratios of 0.5 and 1.5. On suction surface, the introduction of coolant pulsation results in the decrease of cooling effectiveness. On pressure surface, coolant pulsation at high blowing ratio can improve coolant coverage. Starting vortex is the typical structure in pulsating film cooling. However, on suction surface, due to fully-turbulent mainstream, plenty of small-scale vortices play a dominating role in flow fields, and the effect of starting vortex is unobvious. The statistic characteristics and power spectrum density (PSD) of velocity fluctuation were also analyzed in detail. The results show that the disturbance of coolant jet on suction-side mainstream boundary layer is very weak, However, on pressure side, coolant pulsation causes notable increase of PSD and turbulent kinetic energy.