An Experimental Investigation of Showerhead Film Cooling Performance on a Turbine Blade

Experimental tests were performed to investigate the film cooling performance at the leading edge region of a turbine blade using the Infrared Radiation (IR) thermography technique. The test blades were enlarged by five times the natural size with three showerhead rows of radial-angle hole and one row of streamwise angle hole on pressure and suction side, respectively. Six different leading edge cooling geometries were designed by varying the radial angle from 35 degrees to 90 degrees. The effects of mainstream Reynolds number and coolant-to-mainstream blowing ratio were discussed. Results show that the blowing ratio has a marked influence on the cooling effectiveness with the existence of an optimum blowing ratio. High mainstream Reynolds number produces larger coolant flow rate and hence better cooling effectiveness. For x/C<0.15 on suction side close to the stagnation region and the overall pressure side, small radial angle improves the leading edge film cooling performance,whereas large radial angle facilitates the effectiveness downstream of x/C>0.15 on suction side. In current investigation, 45 degrees showerhead radial angle relatively produces the least pressure loss and 75 degrees or 90 degrees gives the most aerodynamic loss that increases with the blowing ratio. (C) 2015 The Authors. Published by Elsevier Ltd.