Gas Temperature Measurement in the Hot Section of Turbine Engines

Abstract

An optical sensor system extends gas temperature measurement capability in turbine engines beyond the present generation of sensor hardware for production engines. The sensing element incorporates a thermally emissive insert to generate an optical signal proportional to the gas temperature at the tip of the probe. The use of a sapphire lightguide allows operation above the melting point of nickel based alloys. Sensor development for aircraft turbines has included flight hardware for use on the Fiber Optic Control System Integration (FOCSI) Program sponsored by NASA Lewis Research Center. The optical probe harness measured exhaust gas temperatures in a General Electric F404 engine. Signals from four probes were optically combined at a single detector assembly to determine the average gas temperature. A comparison of optical and thermocouple temperature measurements was conducted during a preflight engine test. The durability of the probe design has been evaluated in an electric-utility operated gas turbine under the sponsorship of the Electric Power Research Institute. The temperature probe was installed between the first stage rotor and second stage nozzle on a General Electric MS 7001B turbine at Houston Lighting and Power Company. Two probes have been used in the field test and they have a combined total of 4660 hours of operation near 1600°F and 330 starts.