In-situ heat transfer measurements on coated and uncoated turbine blades of a full-scale turbine

Abstract

An experimental study was conducted to measure the heat transfer coefficient distributions on cooled rotor blades of a low-pressure turbine in an operating heavy duty (288 MW) gas turbine engine. Heat transfer data along the midspan of the blades are presented in terms of Nusselt numbers for a set of thermal barrier coated and uncoated blades, respectively. The influence of the Reynolds number and incidence angle on the heat transfer rates are demonstrated and discussed. In the measurement technique, the gas turbine is subjected to thermal transients at various engine operating conditions. During these transients the surface temperatures of the rotating blades are measured by means of an infrared pyrometry system. The distribution of heat transfer coefficients is determined from these temperatures and the measured change of an upstream reference gas temperature. The associated measurement errors are assessed using a Monte Carlo analysis.