Nonlinear Effects of Krypton Flow in a Micronozzle with a Cylindrical Tube

This paper considers krypton flow in a micronozzle with a cylindrical tube. A standardized conical nozzle elongated with cylindrical portion performs gas discharge into a vacuum chamber at a pressure of $10^{−2}$ Pa. Under such conditions, a low temperature area is formed in the central part of the jet with gas condensation. The particles are entrained by the gas flow. The portion with a constant section behind the nozzle should focus the supersonic flow part and the condensed particle flow and also decrease particle dispersion behind the nozzle throat.
The paper expresses a mathematical model of homogeneous gas motion with respect to formation processes and the growth of condensation nuclei. Since the condensed particles are small, the research is carried out with a single velocity motion model. The results obtained have shown that the application of the cylindrical tube leads to nonlinear flow effects. The flow responds to: the geometrical exposure related to flow transition from the conical diverging nozzle into the cylindrical tube, heat exposure and mass outflow due to particle formation and growth, and considerable friction force exposure due to the small sizes of the channel. The sum total ofthese factors leads to an insignificant deceleration of the supersonic flow part and highly impacts condensation.