Experimental investigation on the improvement of film cooling efficiency with a V-shaped micro-vortex generator

Abstract

An experimental investigation was performed to assess the impact of a V-shaped micro-vortex generator (VG) on film cooling (FC) efficiency. The study involves injecting coolant gas from a downstream inclined cylindrical hole, while measuring flow characteristics and film cooling efficiency using particle image velocimetry (PIV) and pressure-sensitive paint (PSP), respectively. The width and streamwise location of the VG are systemically studied to provide a comprehensive guideline for the selection of VG geometrical parameter. The data reveal that the width of VG can affect the strength of anti-counter-rotating vortex pair (anti-CVRP) and the spanwise distance between the two vortices in the anti-CVRP. There is an optimal VG width (i.e., W = 2.5D) for the enhancement of film cooling efficiency within the blowing ratio (BR) range of 0.2 ≤ M ≤ 0.8. In addition, it was found that the reduction of the streamwise distance between the VG and the cooling hole does not always improve film cooling performance. The attenuation of the cooling effect in the streamwise direction is significantly accelerated if the VG is placed nearby the cooling hole.