Experimental and Numerical Studies on Leading Edge Film Cooling Performance: Effects of Hole Exit Shape and Freestream Turbulence

Abstract

This study deals with the experimental and numerical studies of the effect of hole exit shape and free-stream turbulence on turbine blade leading edge film cooling. The study examines several test cases with two blowing ratios (BR = 1.0 and 2.0) and three mainstream turbulence intensities (1.0, 3.3 and 12.0%) using two types of leading edge models with cylindrical holes and diffuser holes [1]. The leading edge model consists of a semi-circular part of 80mm diameter and a flat after-body. In this study total pressure loss coefficient is measured by total pressure probe. Film effectiveness and heat transfer coefficient on the model surface are measured by the transient method using thermochromatic liquid crystal with video camera. In addition, detailed investigation of the film cooling is carried out using CFD simulations. RANS approach using Shear Stress Transport turbulence model and Detached Eddy Simulation (DES) approach are employed to solve the flow field. In the case of diffuser hole, the effect of mainstream turbulence intensity appears significant, and its spanwise averaged film effectiveness is decreased.