پیش بینی فشار گرادیان و وقفه در تعداد ایتوویوس کوچک جریان تفکیک مایع-مایع

The segregated flow pattern, which occurs in a 26.1 mm diameter, horizontal, stainless steel test section, is investigated. Pressure gradient and in situ phase distribution data were obtained for different combinations of phase superficial velocities ranging from 0.05 m·s−1 to 0.96 m·s−1. For the current small Eötvös number liquid-liquid system (EoD=4.77), the dominant effect of interfacial tension and wall-wetting properties of the liquids over the gravity is considered. The approach introduces the closure relationship for the case of turbulent flow in a rough pipe, and attempts to modify the two-fluid model to account for the curved interface. In present flow rates range, wave amplitudes were found small, while interfacial mixing was observed. An adjustable definition for hydraulic diameters of two fluids and interfacial friction factor is adopted. The predicted pressure gradient and in situ phase distribution data have been compared with present experimental data and those reported in the literature.

Flows of two immiscible liquids occur over a wide range of volumetric flow rates in pipelines for multiphase flow transport. In particular, in the petroleum industry, mixtures of oil and water are transported in pipes over long distances [1]. In order to design the transport and production systems, prediction of oil-water flow characteristics, such as flow pattern, water holdup and pressure gradient, is required in many engineering applications [2]. Despite their importance, oil-water flows have not been studied to the same extent of gas-liquid flows [3], and only some mature theories for gas-liquid flows are modified for the development of modeling liquid-liquid flows. It is noted that the flow structure of oil-water mixtures in pipes is quite different from that of gas-liquid mixtures. The density difference between oil and water is relatively low [4], while the viscosity ratio encountered extends over a range of many orders of magnitude [5]. Also, the occurrence of shorter interfacial waves and smaller dispersed phase droplets are related to the lower free energy at the interface [6]. Furthermore, oil-water mixtures may show a Newtonian or non-Newtonian rheological behavior as the result of emulsification and dispersion [7, 8]. Therefore, the various concepts and results related to gas-liquid two-phase flows cannot be simply applied to liquid-liquid systems [9]. The main difficulties in modeling oil-water flows arise from the interface between phases and the discontinuity associated with them. Much effort has been given to the flow patterns and their transition, and the corresponding theoretical analysis, similar to Taitel and Dukler’s [10] two-fluid model, is commonly used for the prediction of design parameters, such as phase fraction and pressure gradient. Trallero et al. [11] observed flow patterns in a 50.8 mm I.D. straight pipe using a refined oil with a viscosity of 28.8 mPa

Extensive experimental and theoretical studies for oil-water segregated flow have been conducted using a 26.1 mm I.D. horizontal pipeline. The oil-water interfacial behavior was observed carefully. Due to the dominant effect of interfacial tension and wall-wetting properties of the liquids over the gravity, especially EoD