The Effects of Condensation on the Flow Field Properties In Free-Jet Expansions of Argon

摘要

Molecular beam techniques and a time-of-flight velocity distribution detector system were used to investigate the effects of condensation in free-jet expansions of argon. A 1-in.-diam skimmer cooled to 22K was used to eliminate skimmer interaction. The data reported are for 170, 300, and 600K argon expanded into a vacuum from source pressures of from 10 to 10,000 torr and with a nozzle-skimmer separation distance of 650 nozzle diameters. The data revealed that the terminal velocity of the monomer species can be greater than predicted when condensation occurs. This is hypothesized to be the result of the heat of condensation being added to the flow field. Also, when condensation occurs, the static temperature increases. Terminal speed ratios as high as 27.5 were measured during these tests. (Author)