| As an important part of the subsea production system,choke valve is used to adjust the flow rate and velocity of the production unit and to control the operation and closing of oil and gas wells.The terrible working environment,high working pressure and the impact of high speed fluid with sand make erosion the main factor of valve failure.This thesis establishes valve model of fluid domain and uses ICEM CFD for meshing.It chooses standard k-? turbulence analysis model from Fluent to get the flow field distribution characters of valve based on control equation of computational fluid dynamic and discrete phase.This thesis combines with a variety of erosion theory to select appropriate control factors of underwater choke valve,establishing erosion model.Due to the limited experimental condition,the erosion experimental data from Baker Oil Company is selected to verify that the control model is suitable for this paper.The erosion rate and rules of choke valve is obtained by using the discrete phase model and erosion model.To explore the change rules of fluid field in valve along with the change of valve opening,a regular model close to the origin model is found first,and then twenty models of different opening are calculated,from which the rules and forming mechanism that the velocity,pressure,maximum erosion rate and average erosion rate change along with the change of opening are obtained.After having a good command of erosion regularity and mechanism,the end of inlet pipe is designed a cone-shape,which leads to the reduction of particle concentration in valve chamber and obviously decreases the erosion of upstream valve body.To decrease the erosion of downstream valve,cage sleeve is designed a double layers structure,the comparison of coaxial dislocation of a orifice is made to find out the reduction effect in erosion and select optimal structure.The erosion rate of the improved upstream pipe in the valve decreases by 13.47% and 16.42% in downstream pipe. |
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