| Oil water annular flow is mainly used in long-distance pipeline transportation of heavy oil. It can be a good solution to these problems, such as poor liquidity because of the heavy oil viscosity and the pressure decreases while transportation. It needs less money and has remarkable effects, but its stability is lower. In the process of pipe transportation, it is easy to produce the phenomena of vortex and jet through the valves. The flow pattern was severely destroyed and seriously influences the transmission efficiency. Therefore, this paper will begin a study to the flow patterns of oil and water annular flow through different valve opening.This paper’s research object is oil water annular flow. Both numerical simulation and experiment were adopted to research the disturbance suffered by different valve opening degree while through the oil water annular flow. Then the simulation result was analyzed. The change rules of internal pressure difference, vortex position and jet distance were summarized. More details is as follows:(1)Based on the VOF multiphase model coupling model Level Set algorithm and the standard turbulence model by FLUENT, the author have a transient and dynamic simulation to the effect of valve opening of the annular flow of water, and the change of flow under different open degrees is obtained;(2) The research was conducted experimentally according to the simulated conditions. The author employs high-speed photography to obtain the data of pressure difference and flow rate of the valve before and after the different opening, then compared the results of simulation and it is proved that errors is within permission, which validates the numerical results;(3) The effects of different valve opening and different flow velocity on the flow characteristics of oil water annular flow were analyzed. It is found that when the valve opening of the pipeline is 30%, the erosion is most serious and the swirl is the most strongest. The flow evolution law of oil water annular flow through valve is also summarized. The author found that before the valve opening up to 40%, with the increase of opening of the swirl, whirlpool gradually close the valve body; when it reach 40%, the whirlpool is moving away from the valve body;(4) The author analyzed the variation section of oil phase volume fraction in different valve opening degree and found that the oil phase volume fraction reaches the maximum when the valve opening is 30%. The analysis of different flow velocity shows that the volume fraction of oil is maximum when the oil phase flow rate reaches 2.06m/s. Greater than or less than the flow rate will reduce the volume fraction;(5) The adhesive condition of surface of pipe was analyzed, and it shows that the oil phase flow rate of 1.2m/s is at most apt to adhere. The viscosity is bigger, the adhesive on the wall is more easily. Increasing the flow rate can reduce the effect of viscosity on the wall;(6) Dynamic simulation of the oil and water annular flow shows that increasing the valve opening speed is beneficial to the improvement of the valve flow field. |
