MULTIPLE-LINE CORRELATION AND LASER ABSORPTION SPECTROSCOPY FOR IN SITU SHOCK-TUBE COMBUSTION STUDIES
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Date
1980
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Publisher
Ohio State University
Abstract
In situ shock-tube chemical kinetic studies of combustion systems require specific and quantitative spectroscopic methods for concentration-time history measurements of reacting species which do not suffer from interferences by other species. As typical examples for this purpose, we have determined multiple-line correlation-absorption $coefficients^{1}$ at $2259A(\Delta \lambda =39A)$ of low pressure ($\sim 5$ torr) emission lines by high-pressure ($0.5\sim$, atm$\sim 2.1$) and high-temperature $(905\sim T, ^{\circ} K\sim 2015)$ lines in the (0,0) band of the NO $\gamma$-band system and near line-center infrared absorption $coefficients^{2}$ at $3.329\mu$ of a He-Ne laser line by a high-pressure ($0.5\sim $p, atm$\sim 2.4$) and high-temperature $(965\sim T, ^{\circ} K\sim 2710$) line in the $\nu_{3}$-fundamental system of $CH_{4}$. The multiple-line absorption obeys an effective absorption coefficient for infinitely narrow emission lines and line-center absorption by isolated Voigt-lines with a common width. This model is applicable for a wide range of experimental conditions encountered in combustion $systems^{3}$ and results in a band f-number which differs by only $+6%$ from the preferred value when known line-width data are used. The laser-line absorption can be approximated by the line-center absorption of a Voigt-line for a symmetrical top and agrees at $300^{\circ} K$ (within $-4.5%$) with previous data when known line-width data are applied. The outlined methods are generally applicable and show that simple and analytical, quantitative $models^{4}$ for absorption data relevant to combustion studies are feasible. However, they require new experimental data for band-model and line-width parameters for many reactant, intermediate and product species. Examples are given of molecules and radicals of interest.
Description
1. K.G.P. Sulzmann, J.M. Kline and S.S. Penner, JQRT 21, 475 (1979) 2. W.M. Heffington, G.E. Parks, K.G.P. Sulzmann and S.S. Penner, JQRT 16, 9 (1976). 3. K.G.P. Sulzmann, JQRT 22, 195 (1979). 4. S.S. Penner and D.B. Olfe, Radiation and Reentry, Ch. 1, Academic Press, New York (1968).-
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