Radiation processes related to oxygen-hydrogen combustion at high pressures

Abstract

Radiation related to the combustion of liquid-oxygen jets in gaseous hydrogen was studied by measuring the intensities of OH, O 2 , and H 2 O radiation in a combustion chamber equipped with windows. Over-all oxidant-fuel weight ratio ( o/f ) was varied from 1 to 10 at a chamber pressure of 24 atm. Maximum intensities were measured at mixture ratios near stoichiometric. Gas temperatures derived from the measured color temperature of a tungsten plate in the gas stream, corrected for losses, agreed with theoretical temperatures of the products. Gas radiation appeared to be thermally excited and in local equilibrium at all locations within the combustor. Measured radiation from the upstream region of a stable combustor veried little with o/f ratio. Intensities initially increased in the direction of gas flow due to reaction and then decreased as the burned gas was diluted with excess reactant or cooled by heat transfer to the walls. Ultraviolet and total radiation data showed that the reaction proceeded at approximately a constant rate until the limiting reactant was consumed. The distance required to complete the reaction varied from 1.5 to 12 in. as o/f was varied from 1 to 9. Measurements made in a second, unstable combustor (axial pressure and velocity oscillations) showed that reaction distances were reduced to 1 to 6 in. for the same o/f variation of 1 to 10. The extents of reaction in the two combustors were compared to the predicted trends for turbulent mixing or vaporization. Combustion appeared to be controlled by mixing in the stable combustor and by vaporization in the unstable one.