EXPERIMENTAL STUDY OF PRESSURE DROP AND MODELING OF INTERFACIAL SHEAR FOR VERTICAL ANNULAR FLOW

摘要

The knowledge of the interfacial shear stress is not only essential for estimating the pressure drop but also is fundamental for modelling two-phase flow phenomena. Most annular flow interfacial shear stress models in the open literature are formulated based upon the sand-roughness model, which diverge from reality to some extent because of the mobility of gas-liquid interface. In view of this, a prediction model of gas-liquid interfacial shear stress for vertical annular flow has been proposed, which takes the interfacial characteristics into account, i.e. the local disturbance wave shapes obtained through processing the time trace of liquid film thickness that is measured using high-speed videos and extracted by the Matlab code in our previous work. What is more, the influence of the entrainment-deposition process and formation of gas eddy caused by the disturbance wave height when the gas core moves through the disturbance wave and subsequently encounters an abrupt expansion on the interfacial shear stress are incorporated into the model. The results predicted by the current model show that the interfacial shear stress has an increasing trend for the increase of both gas and liquid superficial velocities, and the non-dimensional pressure drop originating from the interfacial shear stress is in the form of c_(js) =33.6 Re_x~(-091) Re_f~(0.30).