Numerical simulation of film cooling effectiveness on a flat plate

Numerical Simulation has been conducted to study film cooling effectiveness on a flat plate. Three-dimensional geometry was generated and the effects of blowing ratio and geometrical shape were studied. A cylindrical round, simple angle (CYSA) and laterally diffused, simple angle (LDSA) hole with a streamwise angle of 30 degrees and spanwise angle of 0 degrees were used. Hole length to diameter ratio (L/D=4) is constant for all geometries. Also the diameter of film cooling hole for different cooling holes at the entrance surface (D = 10mm) is constant. The blowing ratio ranges from 0.5 to 1.67, and the mainstream Reynolds number based on the mainstream velocity and hole diameter (Re-D) was 8563. Both local and lateral averaged values are presented. Results have a good correspondence with experimental data obtained by Yuen and Martinez-Botas (Int. J. Heat Mass Transfer 2003; 46:221-235). The simulation results show that cooling hole shape affects film cooling effectiveness significantly. The LDSA hole decreases the momentum of jet flow at the exit area of the hole and avoids lift-off phenomenon. Counter-rotating vortex formed downstream of the hole is weaker for the LDSA hole and secondary flow is not powerful enough to disturb the jet flow Structure next to the wall. Also the results show that the LDSA hole has a better lateral coverage due to the diffused shape of the hole and has a higher effectiveness value in a wider region on the wall. Copyright (C) 2008 John Wiley & Sons, Ltd.