Transient Cooling of a Spherical Mass of High-Temperature Gas by Thermal Radiation

This paper considers the transient cooling of a spherical mass of high-temperature gas which is surrounded by the cold atmosphere. The ionization and dissociation phenomena are neglected, and it is assumed that energy transfer by convection is negligible in comparison to radiation. The radiation transfer problem has been formulated exactly. For the case of a gray gas, approximate solutions are obtained for the temperature inside the sphere as functions of time and space coordinate by the method of moments. The local radiation flux is then evaluated for two different initial temperature distributions and several value of the optical radius.