DESIGN OF A DIODE-LASER SENSOR TO MONITOR WATER-VAPOR IN HIGH-PRESSURE COMBUSTION GASES

Citation
V. Nagali et Rk. Hanson, DESIGN OF A DIODE-LASER SENSOR TO MONITOR WATER-VAPOR IN HIGH-PRESSURE COMBUSTION GASES, Applied optics, 36(36), 1997, pp. 9518-9527
Citations number
19
Journal title
ISSN journal
00036935
Volume
36
Issue
36
Year of publication
1997
Pages
9518 - 9527
Database
ISI
SICI code
0003-6935(1997)36:36<9518:DOADST>2.0.ZU;2-Y
Abstract
The design of a diode-laser sensor to monitor water vapor in high-pres sure combustion gases is described. The sensor, which employs a multip le-fixed-wavelength absorption strategy, has the potential to simultan eously monitor the water mole fraction and the temperature and pressur e in high-pressure and high-temperature environments. The conventional scanned-wavelength strategy, employed in previous diode-laser sensors , is shown to be ill-suited for high-pressure applications. The applic ation of impact and additive approximations in the modeling of H2O abs orption features at high pressures is validated experimentally for num ber densities as high as 18 amagats. Criteria to select optimum wavele ngth combinations for the fixed-wavelengths strategy are discussed. Op timum wavelength combinations that meet these criteria are identified for different temperature and pressure ranges of interest to combustio n applications. The proposed sensor configuration and a strategy to ob tain the baseline (zero absorption intensity) in high-pressure environ ments are also described. Line-shape models that are appropriate for d ifferent temperature and pressure regimes are identified. (C) 1997 Opt ical Society of America.