大型ガスタービン冷却空気流量のヒータ法による計測

抄録

In a large gas turbine, data on cooling air flow rate is needed to analyze not only the temperature of both stators and blades but also its efficiency. However, an ultrasonic flowmeter is not useful because the measurement position becomes hot, usually exceeding 300 degrees centigrade. Furthermore, an insert type flowmeter cannot be used because it requires additional pipe processing for installation and also causes a pressure loss. Accordingly, we tried to use the heater method. In this method, a circumferential heater is attached to the outside of a pipe and then the axial temperature distribution on the outside of the pipe, which is influenced by fluid velocity in the pipe, is measured by thermocouples. The velocity is analyzed on the basis of the temperature distribution in the pipe. Measurements were conducted at two kinds of cooling air pipe in a gas turbine for power generation. In one cooling air is extracted from the 13th stage of a compressor and supplied to the 2nd stator s of the gas turbine; in the other, cooling air is extracted from the 9th stage of the compressor and supplied to the 3rd stator s of the gas turbine. As a result of the measurement, the theoretical temperature curve is closely fitted the measured temperature values in each. These results suggest that the measurement method was effective.