Gas-liquid two phase flow occurs extensively in petroleum industry. In gas-liquid two-phase flow, droplet entrainment in the gas phase and dispersed droplet adheres to the tube surface was usually observed in experiments; when gas velocity is larger than the critical velocity for entrainment.
Based on this new information, a new model is prosed to predict the liquid hold up and pressure gradient in stratified and annular flow, which could be considered the correction of Fan's model. The proposed closure relationships include the viscosity and density of the gas mixture weighted by gas and entrained droplet volume; the gas mixture-wall friction factor weighted by gas-wall friction and entrained droplet-wall friction; the increased flow rate of gas mixture and the decreased flow rate of liquid due to droplet entrainment. Then apply these new relationships into the momentum equation of gas mixture and calculation of interfacial-friction Factor, then liquid holdup and pressure gradient are solved through iterative calculation.
Then, the basic parameters of the proposed model were adjusted to agree with the stratified flow laboratory data from Meng and Fan's experiments. And the predictions of holdup and gradient are agreed well with that of laboratory data. What's more, the predictions are more accurately than Fan model when there have existed droplet entrainment.