Scanned- and Fixed-Wavelength Absorption Diagnostics for Combustion Measurements Using Multiplexed Diode Lasers

摘要

A multiplexed diode-laser sensor system comprising two diode lasers and fiber-optic components has been de- veloped to nonintrusively monitor temperature and species mole fraction over a single path using both scanned- and fixed-wavelength laser absorption spectroscopy techniques. In the scanned-wavelength method, two InGaAsP lasers were current tuned at a 2-kHz rate across H_20 transitions near 1343 nm and 1392 nm in the 2v_1 and v_1+v_3 bands. Gas temperature was determined from the ratio of single-sweep integrated line intensities. Species mole fraction was determined from the measured line intensity and the calculated line strength at the measured temperature.