Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.
The effect of imperfections in film-cooling nozzles on the
flow fields and cooling effectiveness is studied. Measurements
are performed using laser induced fluoresce, particle image
velocimetry and thermo-chromic liquid crystal sheets. Different
positions, shapes (square, triangular and round) and sizes (5-
25% blockage) of imperfections are used to investigate the role
of the nozzle geometry at different velocity ratios (0.15-1.50)
with a fixed nozzle angle (37o). Results will show that the
position and size of the geometry disturbance are determining
factors in the resulting cooling effectiveness, through their
effect on the vortex-structures at the nozzle outlet. In some
cases, the imperfect holes lead to a significantly improved
performance, while in some other cases they deteriorate it.