Comparisons on flow characteristics and film cooling performance of cylindrical and sister holes with/without internal coolant crossflow

Simulations and comparisons on the influence of internal coolant crossflow of a novel film cooling hole design, called “sister holes”, and a baseline cylindrical hole were performed with an established turbulence model. The results show that sister holes can provide better film cooling performance than the baseline case at three blowing ratios, and as the blowing ratio increases the sister holes show significant advantages. At a high blowing ratio, the simple cylindrical hole provides very poor cooling effectiveness, since the jet penetrates into the passage flow due to the high jet velocity and the action of a counter-rotating vortex pair. Compared with the cases using a plenum feeding the film cooling holes, the cases with internal coolant crossflow show higher laterally-averaged film cooling effectiveness because deflection of the jet is caused by the crossflow.