Determining parameters in nonequilibrium flow of a gas with homogeneous condensation

Analytic expressions are obtained for the parameters which determine the number of particles (clusters) and their mean radius and the supercooling at the starting point of active homogeneous condensation (the Wilson point). With a given law p=f(T), such parameters are the temperature T_s at the dew point and the mean cooling rate = dT/dt of the gas from the dew point to the Wilson point. In this context, with T_s = const and = const, the processes of nonequilibrium homogeneous condensation in the P-T diagram corresponding to the various initial states after the Wilson point may be described approximately by a single curve. So the parameters T_s and are determining parameters for the whole process of nonequilibrium homogeneous condensation. Equations are given which enable us to estimate approximately the cooling rate for flows in nozzles and jets. Computation results are given for steady flow in a Laval nozzle and unsteady spherically symmetric expansion of a gaseous sphere into a vacuum; these results demonstrate the noted regularities. Despite the great amount of literature, both periodical and monograph, on the nonequilibrium condensation of vapors, the important question of the determining parameters for the process of a homogeneous nonequilibrium condensation has not been studied to any great extent 1].Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 80–87, May–June, 1985.