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ISSN Imprimir: 2150-766X
ISSN On-line: 2150-7678
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TEMPERATURE AND CONCENTRATION MEASUREMENTS IN HOSTILE COMBUSTING FLOWS USING MULTICHANNEL ABSORPTION SPECTROSCOPY
RESUMO
Multichannel absorption spectroscopy has been used to determine simultaneously the temperature and absolute species concentrations in the gas-phase flame above solid propellant samples burning at pressures from 0.1 to 2.0 MPa. The apparatus consists of a windowed chamber, broad-band arc lamp and two 0.32-m spectrometers with intensified photodiode array detectors. Pinhole apertures, 0.1 and 0.2 mm in diameter, were mounted near the propellant samples to define the spatial resolution. Typically, 30 spectra were recorded during a propellant burn. Details of the analysis that account for the significant wavelength nonlinearity which is present in the data are given.
Sample spectra and analysis fits are presented for OH and NO from both laboratory flames and propellant burning at elevated pressures. Plots of the measurements of both the temperature and absolute concentrations of OH and NO as functions of distance from the surface of a sample propellant are presented. Measured mole fractions are as high as 0.20 for NO in the dark zone and 0.002 for OH in the post-luminous flame zone. Estimated total error in concentration measurements is 30%. Temperature errors are indicated to be 50 K from data fits and 100 K based on comparison of OH concentrations observed vs. those calculated thermochemically.