Effects of Inclined Blowing on Effusion Cooling in a Mach-2.67 Boundary Layer

Direct numerical simulations are used to investigate the method of effusion cooling in a laminar Mach-2.67 boundary layer. Air is employed as mean-flow and coolant gas and is introduced into the boundary layer through two staggered or aligned rows of holes by means of a modeled blowing approach. First, the effects of streamwise inclined blowing with various inclination angles αc are investigated. It is demonstrated that a decreasing inclination angle results in an increasing cooling effectiveness, since the coolant gas remains closer to the wall and the generated vortices are smaller. Furthermore, the influence of an additional compound angle βc is analyzed. In the present work four different cases are investigated, where the effects of the blowing direction, i.e. inclination angle αc and compound angle βc, and the hole arrangement, i.e. aligned and staggered rows, are presented. It was found that a further improvement of the cooling performance can be achieved for the case with aligned rows and opposingly oriented compound angles. There, the cooling effectiveness is found to be significantly higher than for the investigated reference case with two staggered rows of holes without compound angle.