Enhancement of film cooling effectiveness using upstream vortex generator

A numerical study was carried out to explore the influence of triangular with concave edge shaped (TCES) upstream ramp on the film cooling effectiveness (FCE) and flow characteristics. The main objective of this study is to obtain the performance of the newly proposed upstream ramp on FCE and to establish that it provides better thermal protection by increasing the lateral diffusion of coolant on the surface compared to the baseline case and continuous triangular-shaped (TS) upstream ramp. Four different cases were investigated, including baseline case, TCES with s/d = 1, TCES with s/d = 1.5 and triangular-shaped (TS) upstream ramp. Coolant streams were injected through a circular jet hole on the target surface with an inclination angle of alpha(c) = 35. Computations were carried out with different blowing ratio (M), including, 0.40, 0.85, 1.00, and 1.25. Results showed that TCES has a significant potential of improving coolant dispersion towards the lateral direction on the surface by means of generating a pair of strong anti-counter rotating vortex (anti-CRV) in the jet flow region compared to the baseline case. Correspondingly TCES with s/d = 1 upstream ramp is the best design especially considering thermal protection. Moreover, area-averaged FCE enhances 441.35% by using TCES with s/d = 1 upstream ramp on the surface under inspection compared with the baseline case for the blowing ratio of M = 1.25.