Experimental investigation on the overall cooling effectiveness of t-type impinging-film cooling

•The streamlined inducting slab shows a good cooling effect.•The effects of flow and geometry parameters on cooling performance were obtained.•The empirical correlations of overall cooling effectiveness were summed up. This paper presents an experimental investigation of impinging-film cooling concerning the effects of various factors on overall cooling effectiveness η. The factors include blowing ratio M (0.31≤M≤1.84), non-dimensional jet-to-plate pitch Zn/d (1≤Zn/d≤2), non-dimensional spacing of jet holes Yn/d (1.6≤Yn/d≤2.4) and diameter of jet hole. The results show that overall cooling effectiveness invariably increases with a raise in blowing ratio. As non-dimensional jet-to-plate pitch increases, the cooling performs better. The decline of non-dimensional spacing of jet holes improves the overall cooling effectiveness at higher blowing ratios (M≥0.91), which was not observed in cases with low blowing ratios (M≤0.61). The variation of hole diameter (1.0–1.8mm) has little influence on cooling performance.