The Pulsed Thermocouple for Gas Turbine Application

Abstract

A mechanically pulsed suction thermocouple has been developed. The gas to be measured is sucked through a sonic orifice, thus eliminating the influence of the velocity inside the combustor. The signal from the thermocouple is processed by an analogue circuit. Contrary to the usual approach to the problem of dynamic temperature measurements (i.e., the attempt to find an exact solution to the extrapolation of the temperature rise curve) in this work, a calibration of the probe was done. This calibration showed very little scatter and a good repeatability. The overall measurement accuracy was better than ±1 percent. As a test of application, a partial survey of the temperature distribution within an aircraft gas turbine combustor was done. A satisfactory agreement was observed between temperatures measured by the thermocouple and those determined from gas analysis. In this test the pulse thermocouple proved to be a reliable and fast tool for the measurement of local gas temperatures.