Numerical investigation on the effect of different transverse trench configurations on film cooling effectiveness

The flow fields and cooling effectiveness of the film cooling from a row of cylindrical angled holes embedded in different transverse slots configurations were investigated numerically in several blowing ratios, to reveal the effects of narrow trench, wide trench, and inclined trench with the same trench depth on the film cooling performance from the flowing mechanism. The simulation results of inclined trench model were compared with experimental data of shaped holes. It is found that, for the embedded holes, the jet injected into the slot loses momentum at the exit of the slot; the penetration of the film secondary flow into the cross flow is suppressed and the secondary flow is pushed downwards on to the surface, resulting in better coverage. At low blowing ratio, the inclined trench has superior cooling effect, while at high blowing ratio the narrow trench has superior cooling effect. A lateral vortex appears in the wide trench; a pair of taper vortex appear in the narrow trench; and a pair of counter rotating vortex appear in the inclined trench. The trailing edge wall of the trench plays an important role in the lateral diffusion of the cooling film.