Surface and Gas Temperature Measurements Along a Film Cooled Wall

Abstract

Film cooling is widely used to protect critical sections of propulsion devices from extreme heat loads in the internal flowpath. Many studies have been conducted to formulate scaling laws characterizing the effectiveness of film cooling in a variety of configurations for the development of engineering correlations. There is an emerging demand for detailed measurements near film-cooled surfaces to support computational model development of these complex wall-bounded flows. In this study a unique hot wind tunnel facility was used to perform detailed measurements in a canonical two-dimensional thermally stratified wall-jet configuration. Wall temperature, adiabatic effectiveness, and turbulent flow measurements were performed over a range of carefully controlled inlet conditions. Far-field laboratory effectiveness measurements compare well with previously developed scaling laws; however, the effect of the ratio of mainstream to cooling stream temperature is significantly underpredicted. The micro-thermocouple probe used in this study provided mean flow temperatures and detailed turbulent statistics characterizing the nearwall mixing behavior. The mean flow temperature measurements in the far field demonstrate self-similar behavior whereas fluctuating temperatures indicate fully developed turbulence in the wall layer. The turbulent statistics provided in this study are especially useful for development and validation of computational models of film-cooled surfaces.