In-engine turbine heat transfer measurement

Abstract

The heat transfer coefficient distributions on the rotor blades of a low-pressure turbine in a heavy duty (288 MW) gas turbine engine have been measured. This is the first successful in situ measurement of the heat transfer coefficient in the harsh environment (high temperature, combusted gases) of an operating engine. In the measurement technique, blade surface temperatures and an upstream reference gas temperature are measured, while the engine is subjected to a thermal transient. The temperatures on the surfaces of the rotating blades are measured by means of an infrared pyrometer. The distribution of heat transfer coefficients along the midspan of the blades is then determined from these temperatures and the measured change in the upstream reference gas temperature. The associated measurement errors are assessed using a Monte Carlo analysis. Empirical correlations for stagnation point flow show excellent agreement with the measured heat transfer coefficients in the leading edge region of the blades. The accuracy of the measurements and the low relative cost of the hardware mean that the present measurement approach is well suited for in situ heat transfer measurements of large gas turbine engines.