Part I. Chemical reactions during flow in rocket nozzles. Part II. Gas discharge rates through de Laval nozzles and the experimental determination of desorption rates

Abstract

In Part I, some of the important physical ideas that have been used in an analysis of chemical changes in rocket nozzles are reviewed with particular reference to the three-body recombination reaction. Modified forma of the simple near-equilibrium flow criterion developed about 15 years ago are shown to lead to results that are substantially equivalent to estimates derived from a criterion of Bray. The influence of surface-catalyzed processes on atomic recombination rates in rocket nozzles is considered and found likely to be important in present solid-propellant rocket engines. In Part II, studies of the effective desorption rates of gases (Ar, He, and CO_2) from sand and from silica gel are described. These rates have been determined experimentally by measuring, as a function of time, the pressure drop in a vessel containing the solids when the gases are allowed to discharge through a small de Laval nozzle. The dependence of the desorption rate on temperature has been investigated. A theoretical expression for the rate of desorption from porous solids has been developed assuming that the overall process is diffusion controlled. The experimentally determined desorption rates of Ar, He, and CO_2 from silica gel have been compared with this theoretical expression.