Large eddy simulation of compound angle film cooling with vortex generators

Film cooling is a commonly used approach in high-performance gas turbine engines to insulate the components from the hot mainstream flow. Compound angle injection with orientation oblique to the freestream laterally are employed to achieve wide coolant coverage. The passive control devices of delta winglets are effective in improving thermal performance. In the current study of film cooling by LES, the compound angles are investigated with 35 degrees vertical inclined angle to the cooling wall and 0 deg, 30 deg, and 60 deg lateral inclined angles to the streamwise crossflow. Vortex generators of delta winglets pair are installed upstream of the cooling hole. Adiabatic film cooling effectiveness is examined at the blowing ratio of 1.0 and density ratio of 2.0. The cooling performance improves significantly when the compound angled injection and delta winglets are applied. Mean and instantaneous vortical structures in the near-hole field are presented. The counter-rotating vortex pair (CRVP) associated with streamwise injection changes into a strong symmetric vortex in compound angled cases. Anticounter-rotating vortex pair (anti-CRVP) evolved from delta winglets cancels the strength of CRVP in the streamwise coolant injection case, and the downwash effect of anti-CRVP is weakened with lateral angle increasing.