Large eddy simulation of inclined round jet issuing into cross-flow

Abstract

For understanding of film cooling flow fields on a gas turbine blade, this paper reports on a series of large-eddy simulations of an inclined round jet issuing into a crossflow. Simulations were performed at four blowing ratio conditions, BR=0.1, 0.5, 0.7 and 1.0 and Reynolds number, Re=15,300, based on crossflow velocity and film cooling hole diameter. Results showed that cooling jet flow structure drastically changed with blowing ratio. A pair of rear vortex and hairpin vortex were observed for BR=0.1. A periodic ejection of horseshoe vortex, a pair of hanging vortex, a pair of rear vortex and hairpin vortex were observed for BR=0.5. Similar vortical structures to BR=0.5 were observed for BR=0.7 although horseshoe vortex remained at a leading edge of the hole exit. For BR=1.0, in addition to the former mentioned vortices, spanwise rollers and vertical streaks were observed on an upstream edge of the jet. It was, consequently understood that the ubiquitous counter-rotating vortex pair which can be defined in the time-averaged flow field was actually originated in the different vortical structures with varying BR conditions.