High-Temperature Sensors for Small Gas Turbines

Temperature sensors for application to the turbine inlet of small gas turbine engines were developed. Two thermocouple designs to sense gas temperature were developed and tested. An optical sensor for first-stage turbine blade temperature measurement was tested in the laboratory and on a gas turbine engine. A bare multiple-junction platinum-rhodium thermocouple with a platinum- rhodium radiation shield was tested at temperatures to 2550F. Response time, calibration, drift, and life were measured in a simulated gas turbine environment. A rugged, protected thermocouple probe was developed using advanced materials systems able to operate in an oxidizing environment to 2800F. The radiation sensor consists of a silicon photovoltaic detector, a quartz lens, a high-temperature fiber optic bundle, an interface device, and a signal linearization system. It measures blade temperature and can resolve individual blades. The fiber optic bundle allows remote placement of the temperature- sensitive detector in a relatively cool environment. Silicon detectors provide- high-temperature sensitivity and accuracy with an insensitivity to emittance and transmission errors. A unique interface device protects the optical system from transmission losses resulting from contamination of the optical system.