Coherent Motion Analysis of Turbine Blade Leading Edge Film Cooling: LES Study

Large Eddy Simulation of coherent motions effects on turbine blade leading edge film cooling has been investigated in present study. Detailed consideration of coherent structures, visualized by second invariant of the velocity gradient tensor (Q criteria), on three blowing ratios of ۰.۴, ۰.۸ and ۱.۲ have been examined. Results are in good agreement with the available experimental data. Generally, it has been confirmed that increase of blowing ratios leads to a decrease in film cooling performance. Besides, it has been shown that ejection structures leads to the film cooling performance reduction at their creation position (origin) and downstream of their origin, depending upon theirstrength. Whereas, the wall-ward and outward structures gradually decrease and increase the adiabatic effectiveness respectively, downstream of their origins. Finally, sweep motion declines the lifted vortices such as tube-wise vortex, toward the blade surface, which results in film cooling improvement.

Keywords:

Coherent structures , Ejection , Sweep , Leading edge Film cooling , LES