Current research on infrared radiation from rocket exhaust

Abstract

Infrared radiation heating from rocket exhausts has been of particular interest to NASA in connection with large vehicles of the Saturn class. These vehicles are equipped mainly with two types of rocket engines: the J-2 model for which H 2O is the only radiating species, and the F-1 model for which H 2O, CO 2, CO and carbon particles are the radiating specie. A computer program has been developed to calculate infrared radiant heat transfer from inhomogeneous mixtures of these gases. This program uses a band model to express the absorption coefficients of the gases. The band model parameters necessary for these calculations are the mean line strength S, the mean line half-width γ, the mean line spacing d, averaged over 25 cm −1 increments. Analytical and experimental programs are in progress to complete the determination of these parameters at long path lengths and to include the effects of foreign gases on these parameters. A tentative set of γ's, 1/ d's, S/ d's has been determined, using data and analytical expressions coming principally from the literature. A modified Curtis-Godson approximation is used in the radiative heat transfer calculation and effectively substitutes a hypothetical homogeneous path for the inhomogeneous path. This approximation has been used successfully in predicting atmospheric radiative transmission. This modified Curtis-Godson approximation is experimentally shown to be applicable for strong temperature and concentration gradients for certain wavelengths in the H 2O and CO 2 infrared spectrums.