Non-Intrusive Fiber Optic Temperature Sensor for Internal Combustion Engine Monitoring

Advanced sensors that can withstand the extreme temperatures and vibrations of an operating engine environment are required in order to improve the performance and efficiency of these engines. Present temperature sensor technology requires sensors to protrude into the hot gas stream or be embedded in the component being monitored. These sensors not only interfere with the operation of the engine, but they are quite often temperature limited, short lived, and /or inaccurate. Physical Optics Corporation proposes the use of a narrow field-of-view IR radiation temperature sensor that utilizes recently developed sapphire optical fiber technology and an innovative sapphire non-imaging optical (NIO) element. The sapphire fiber will be drawn to make the NIO a natural extension of the fiber end. Therefore, only a one-piece sapphire probe needs to be exposed to the hot environment of the engine. The sapphire probe can be installed flush with the engine wall, without intruding into the hot gas stream, to monitor the temperature of hot gases or internal engine components. Sapphire's melting point is - 2000"C, far exceeding any temperature limit of internal combustion engines. An IR transmitting fiber will carry the IR radiation to a spectrum analyzer for temperature determination. Anticipated Benefits/Potential Applications - Non-intrusive temperature sensors for monitoring high temperatures can find military and commercial applications. Military applications include test-bed engine monitoring and temperature measurement of metal matrix composite coupons during thermal fatigue cycling. Commercial uses include monitoring combustion process temperatures (automobiles, boilers, etc.) to improve combustion efficiency and decrease pollution emission.