Use of a Thermographic Phosphor Fluorescence Imaging System for Simultaneous Measurement of Film Cooling Effectiveness and Heat Transfer Coefficient

Abstract

This paper describes a novel approach based on the temperature-sensitive fluorescence of a thermographic phosphor (europium-doped lanthanum oxysulfide, La2O2S:Eu+3) that enables the simultaneous determination of both local film effectiveness and local heat transfer on a film-cooled surface. The measurement system is capable of acquiring a series of transient, full-field surface temperature images during a heating process. Using a data reduction procedure designed specifically for three-temperature systems, these temporally resolved temperature maps yield the local film effectiveness and heat transfer coefficient simultaneously. The film cooling test model is a single row of four, 30-degree inclined, discrete holes oo a flat plate. The measuement results exhibit superior spatial resolution with detailed features in good agreement with those using other conventional thermal methods, as well as the liquid crystal imaging technique. One major advantage of this technique is its potential for high temperature and highly unsteady applications.