Gas-Core Turbulence Structure of Annular Flow Passing Through a Throat Section Affected by the Wavy Interface on Liquid Film Flow

Experimental studies were made on the gas-core turbulence structure in vertical upward annular two-phase flow passing through a round tube with a throat section. The gas-core turbulence is affected and modified by the dynamic interaction between gas-core flow and liquid film flow through the wavy interface. The test channel has a throat section, which consist of nozzle, throat and diffuser part, where the cross sectional area of the channel is changed along the flow direction. In the throat section, the flow is in transient state because the flow is accelerated or decelerated along the flow direction as the cross sectional area of the channel is changes. The gas-phase turbulence structure such as the time-averaged velocity profiles and fluctuation velocity profiles were precisely measured by using the constant temperature hot-wire anemometer. For the liquid film flow, the time-averaged film thickness, base-film thickness and interfacial wave height were obtained by using the point electrode resistivity probe. Direct observations for the interfacial waves on liquid film flow such as disturbance waves and ripple were also carried out by using the high-performance camera system to make clear the interfacial wave structure.