Large Eddy Simulation of Inclined Jet in Cross Flow With Cylindrical and Fan-Shaped Holes

Abstract

A large eddy simulation (LES) investigation of the inclined jet in crossflow is presented in this paper. The angle between the hole and the main flow is 35 degrees, which represents a typical film cooling application. Two different geometries, namely the cylindrical hole and the fan-shaped hole, are investigated at a blowing ratio of 0.5, which is a representative value for film cooling. The numerical tool is first validated and then used to study the flow and the film cooling effectiveness of the cooling holes. Both the time averaged and the instantaneous flow characteristics are analyzed. In the time averaged results, the counter-rotating vortex pair has large effects on the mixing of the coolant with the main flow. The instantaneous results show that the mixing of the injected flow with the main flow is highly related to the unsteady coherent vortices. The difference in the cooling effectiveness distribution for the two holes is due to the different coherent vortices. The relationship between the coherent vortices and the temperature distribution is explained in detail. These results show that the vortices distribution at the exit of the hole has important influence on the later development of the hairpin vortices, thus affecting the temperature distribution and the cooling effectiveness.