Experimental study of the motion and shape of a vapor bubble rising in an annular channel at subatmospheric pressure

Abstract

Experimental study was performed for the dynamics of vapor bubble rising in the annular channel at subatmospheric pressure. The gas bubble is formed during boiling of superheated degassed liquid in an annular channel restricted by two glass tubes with the diameters of 25 and 16 mm. It was demonstrated that the dynamics of vapor cavity while rising the vapor bubble in the annular channel demonstrates a qualitative difference from the dynamics for an ascending gas bubble. The behavior is similar to a Taylor vapor bubble behavior in a round tube with a small diameter. One of typical features of vapor cavity behavior in an annular channel is the possibility of vapor cavity decay after the bubble collapse during the pulsation flow mode.