The effect of liquid viscosity on gas wall and interfacial shear stress inhorizontal two-phase pipe flow

An experimental investigation of gas-liquid flow in horizontal pipes is con ducted. Consideration of a stationary liquid phase allows the direct calcul ation of gas wall and interfacial shear stress from measurements of gas vel ocity, pressure drop, and liquid height without the need for any empirical input. The experiments are conducted to determine the effects of liquid vis cosity. The results show that commonly used correlations for interfacial fr iction factor, which are generally developed in rectangular ducts, are inad equate, especially under conditions of increased liquid viscosity. It is sh own that more success can be achieved if the effect of liquid viscosity is considered in the transition to wavy flow. New correlations for shear gener ated by smooth, rippled and wavy interfaces are proposed. (C) 1999 Elsevier Science Ltd. All rights reserved.