Effect of internal coolant crossflow on the film cooling performance of converging slot hole

The effect of crossflow Reynolds number on the film cooling characteristics was investigated on low speed flat-plate facility. The film cooling performance was measured by transient liquid-crystal technique and the flow feature was obtained by numerical simulation. Two film hole cases, converging slot hole case and cylindrical hole case, were carried out at two crossflow Reynolds numbers, Re_c = 50,000 and 100,000 and three blowing ratios, M = 0.5, 1.0 and 2.0. For cylindrical hole, high Reynolds number deteriorates the film cooling effectiveness at blowing ratio of 0.5. However, better film coverages are observed at M = 1.0 and 2.0. At each blowing ratio, high crossflow Reynolds number produces higher heat transfer for cylindrical hole case. The converging slot hole case presents better film coverage in whole region. The film cooling effectiveness and heat transfer are not sensitive to the crossflow at each blowing ratio. Discharge coefficients of two holes are increased as increasing of blowing ratio, while the high crossflow Reynolds number deteriorates the discharge of flow. The numerical results indicate that the different performance of film cooling between two kinds of holes at crossflow condition is mainly attributed to the different development of in-tube vortex.