The Influences of Film Hole Size and Coolant Ejection Angle on Overall Cooling Effectiveness of Laminated Cooling

The laminated cooling or the layered cooling configuration with integrated impingement, rib-roughed and film cooling can result in a high overall cooling effectiveness and is believed to be a promising cooling technology for the next generation of advanced gas turbines. Previous studies found that the relative locations among the film hole, impingement hole and the pin-fin (i.e., cooling element arrangement) have strong impacts on the cooling effectiveness of the laminated configuration. The laminated configurations with staggered arrangement were investigated in the present paper. Two measures were used to enhance the overall cooling effectiveness, including increasing the area ratio of film hole to cooling area and employing angled film hole. Fluid-thermal coupled computations (conjugate heat transfer) were performed for assessing the overall cooling effectiveness and the pressure coefficient, and the computation method was validated by the experimental data. The computational results for the baseline design show that the area-averaged cooling effectiveness is 0.717 at BR = 1.77 and the film cooling needs to be further enhanced. Through enlarging the diameter of the film hole from 0.8mm to 1.2mm, the lift-off of film coolant is restrained and the cooling effectiveness is increased at the downstream of film hole. By employing angled film hole, the area-averaged cooling effectiveness is increased and the coolant flow resistance is also reduced.