Diode Laser In-Situ Fiber-Optic Real-Time Combustion Exhaust Sensor

Real-time in-situ monitoring of trace combustion species from rocket and aircraft engines is desirable because it provides a direct measure of the combustion process, the operating efficiency, and the release of pollutants into the environment. Of particular interest are CO, NO, and CH4, which are produced by liquid propellant rockets and aircraft turbine engines. A sensor that could be incorporated into propulsion systems would have wide-ranging application in both Air Force and commercial transportation systems. To address this opportunity, Spectral Sciences, Inc. proposes to develop a Fiber Optic Real-time Combustion Exhaust (FORCE) sensor that uses a tunable diode laser for rapid monitoring of multiple species in a high-temperature flow. A fiberoptic cable carries the light from the laser/microprocessor module to the probe, which is located in the exhaust duct; the line of sight is near the engine exit. The state of the art in lasers and electro-optic and signal processing components enables the development of a compact, rugged, and reasonably priced instrument with ppm-level sensitivity. In Phase I, a proof-of-principle experiment will be conducted and preliminary design will be developed for a Phase II prototype instrument.| Benefits: In addition to Air Force applications, a major commercial market exists for monitoring trace combustion products from gas turbine and conventional power plants. Continuous emission monitoring is required for the toxic products NO and CO as well as NH3, a byproduct of NO control chemistry. In addition, accurate measurement and control of the CO/CO2 ratio in the exhaust would facilitate the optimization of burner combustion efficiency.|