Evaluation of Wavy-Trailing-Edge Film Cooling Versus Pressure Side Cutback Cooling

Abstract

This study measures the film cooling effectiveness along the trailing edge (TE) of a turbine blade in a linear cascade. The film cooling effectiveness is measured and analyzed using the pressure-sensitive paint (PSP) technique. Two different TE designs are investigated: the standard pressure side cutback and the new alternating discharge design (referred to as a wavy-TE design). The alternating discharge design is a new design with a wavy structure between the pressure and suction surfaces at the TE. The new wavy structure allows the coolant to discharge from the TE so that it alternates between the pressure and suction surfaces. Testing is carried out in a five-blade, linear, steady-state cascade with inlet and exit Mach numbers of 0.20 and 0.30, respectively. The freestream turbulence intensity is measured to be 10.5% upstream of the blade leading edge. Coolant-to-mainstream mass flow ratios (MFRs) vary from 0.30 to 1.25% and coolant-to-mainstream density ratios (DRs) of 1.0, 1.5, and 2.0 are examined. A positive MFR and DR effect is witnessed. The results demonstrate the potential of the alternating discharge as a promising TE design and provide gas turbine designers with an improved TE cooling scheme.