Film Effectiveness Performance for Coolant Holes Imbedded in Various Shallow Trench and Crater Depressions

Abstract

Film cooling adiabatic effectiveness was investigated for various configurations of coolant holes embedded in shallow transverse trenches or circular and elliptical shaped depressions. As a basis of comparison, a shaped hole configuration was also tested. Tests were conducted on the suction side of a simulated vane at a downstream location where pressure gradient and curvature effects were small. For the transverse trench, effects of the trench width with varying depths, the trench wall angle, and the pitch between holes within the trench were investigated with trench depths that ranged from 0.5d to 1d. The crater depressions were tested at a depth of 0.5d. The film effectiveness for the crater depressions was not as good as the best performing trench configuration at that depth, but they all performed better than the baseline configuration of cylindrical holes. The trench configurations were found to have an optimum depth of 0.75d, with little improvement in performance for trench depths greater than this. Comparison of the trench performance with a typical shaped hole configuration showed that film effectiveness for the trench was similar to that of the shaped holes.