Computational and Experimental Study of a Y-Shaped Hole for Film Cooling

Adiabatic effectiveness (η) of film cooling is strongly affected by the geometry of the film-cooling hole. This study presents and assesses a new shaped-hole geometry, referred to as the Y-shaped hole, that seeks to increase η by splitting the cooling flow into three streams for increased lateral spreading and by decreasing the hole's cross-sectional area for increased streamwise penetration. The Y-shaped hole was assessed computationally and experimentally by examining its usefulness in film cooling a flat plate with the cooling flow issuing from a plenum. The computations with and without conjugate heat transfer were based on the Reynolds-averaged continuity, Navier-Stokes, and energy equations closed by the Shear-Stress Transport (SST) turbulence model for the gas phase (steady RANS) and the thermal energy equation for the solid phase. The experimental component used infrared thermography to measure surface temperature, which agreed reasonably well with computations that accounted for conjugate heat transfer. Computations with adiabatic walls show laterally-averaged η produced by the Y-shaped hole to be nearly twice that obtained by the 777 and the W-shaped hole under comparable blowing and temperature ratios.