Experimental Study of Near-Wall Liquid Film Outflow with Co-Current Gas Flow from Nozzle into Vacuum. 2. Flow Structure behind Nozzle

Abstract

Outflow of a near-wall liquid film with co-current gas flow from a nozzle (cylindrical channel) into vacuum is studied experimentally. Special features of near-wall liquid films ejection into vacuum are established with the help of the developed measurement techniques (droplet phase flow structure visualization with ordinary and laser illumination, deposition of droplets on paper substrates, spectrophotometry): turn of the film in the opposite direction at the nozzle lip and its rise along the outer surface of the nozzle against gravity, cooling due to evaporation, disintegration into droplets with the formation of the spatial flow structure, which includes two typical areas: central and peripheral. The temperature of the liquid film formed on the outer surface of the nozzle is measured. It is shown that the film is cooled down to a temperature at which the pressure of liquid saturated vapors becomes equal to the pressure in the vacuum chamber. The distribution functions of droplets by size, direction of fly, and velocity in the peripheral area of the flow are obtained.