Two-Phase flow pattern in the mixing chamber of an effervescent atomizer

This paper deals with an experimental study of the two-phase flow in the mixing chamber of an effervescent atomizer. Not only do operational conditions and media properties affect the process of effervescent atomization but also the pattern (quality) of the two-phase flow. Therefore, it is necessary to describe the phenomena associated with the mixing process. Two-phase flow structure was investigated in a mixing chamber with an inner diameter of 8 mm. During the experiment, the effervescent nozzle was operated in the air pressure range of 1 to 0.5 MPa and mass GLR (Gas-to-liquid- ratio) was between 1 and 25%. Mass flow rates of water ranged from 5 up to 50 g•s-1. Since optical measurement techniques fail to provide sufficient quantitative information on the flow structure at higher GLR we applied the conductivity wire-mesh sensor technology to this problem. Therefore, a new miniature wire-mesh sensor for small-diameter tubes was developed. The measuring principle of this sensor is based on the measurement of electrical conductivity in the crossing points of a wire mesh. Due this principle we used a conductive liquid (deionized water). The two-phase flow in the chamber is highly unstable and the wire-mesh sensor provides also data for an evaluation of two-phase flow pulsation.