Numerical Study On The Water Entrainment By Oil Stream In The Products Pipeline

In the view of the phenomenon of erosion in the low-lying sections of products pipeline, experimental researches were completed in order to study the function of the entrainment of water deposition by the oil stream. Meanwhile, numerical computation model was established, basing on the numerical calculation software FLUENT.The two phase model-VOF method in the FLUENT software was selected for simulating the water deposition entrainment by the oil stream. ComPared with the experimental data, it was approved that the VOF method can accurately predict this phenomenan.It was found both in the numerical and experimental studies that when the velocity of oil stream was low, water deposition would aggregate in the low-lying section of the pipe, with a smooth interface between the two phases. The flow Pattern in this condition was smooth stratified flow. When the velocity of oil stream was higher, water could be entrained to the inclined section, with a disturbance in the interface, and the flow Pattern turned to be stratified wavy two phase flow. Moreover, as the velocity of the oil stream increases more, water droplets were formed and be carried into the oil stream.Seeking to study the water entrainment by the oil stream, user defined functions of FLUENT was developed to access simulation data, such as average water hold up, average interface shear stress, average water velocity, average pressure drop gradient. Factors effecting the entrainment caPability of oil stream such as the diameter of the pipe, the property of the oil, the velocity of oil stream were also analyzed.Through numerical analysis and experimental study, it is thought that a critical condition existed, meaning that only when the velocity of oil stream was increased to a certain value, the water deposition could be entrained completely out of the low-lying section of the products pipe.