EFFECTIVENESS OF LEADING-EDGE COOLING ARRANGEMENTS
Measurements of the film-cooling effectiveness around the circumference of a cylinder are presented as a function of velocity ratio and hole arrangements. The geometrical configuration and flow properties simulate (apart from the Mach number) the flow around the leading edge of a nozzle guide vane or gas-turbine blade. Results, based on mass transfer measurements, were obtained for one, two and three rows of holes; the holes were angled at 30 degrees to the cylinder axis and along the span. The effect of the circumferential location of the rows of holes with respect to the stagnation line is also quantified. In general, the results show that the effectiveness increases with velocity ratio and number of rows of holes and that, with the present pitch to diameter ratio of 3.2, the three-dimensional nature of the geometry is reflected by the downstream measurements.