Temperature wave propagation in a non-gray radiating fluid

Theoretical and experimental studies were carried out on the upward propagation of a temperature wave in a fluid, in which heat is transferred by both conduction and nongray radiation. A harmonic temperature oscillation was imposed on the lower boundary, and the attenuations in amplitude and changes in phase at different altitudes and under different conditions were investigated. Gaseous ammonia and nitrogen were respectively the radiating and nonradiating media selected for experiments and calculations. Spectroscopic data for frequencies, intensities, and widths of individual absorption lines in nine infrared bands of ammonia were determined from theoretical and empirical formulae. They were then compiled as parameters and used in a random absorption band model to obtain the modified emissivity functions, which are essential to the nongray radiative heating calculation.