基于CFD-DEM方法的变径T型流道冲蚀特性研究

目的 研究石油开采过程中,携砂压裂液对变径T型流道壁面冲蚀磨损规律及主要影响因素.方法 针对石油压裂管汇及井下喷砂器等工具中常见的变径T型流道的冲蚀问题,建立了基于CFD-DEM的变径T型流道固液两相流冲蚀磨损预测模型,该模型中颗粒-颗粒、颗粒-壁面碰撞采用逆向迭代碰撞搜索算法,颗粒-流体耦合计算时间步长根据耦合收敛条件自适应调整.将数值方法与正交试验方法结合,分析各因素变化对均值主效应响应的优先排序和各因素的交互作用,并进行了单因素变化对冲蚀规律的影响.结果 单因素分析时入口流速增大,T型流道最大冲蚀速率和冲蚀面积均增大,冲蚀位置向支流道出口处移动,流体携带颗粒能力增强,堆积颗粒数量减小.砂比范围为5％～35％时,最大冲蚀速率与砂比正相关.最大冲蚀速率随粒径的增大而先增大后减小,随变径比的增大而减小.与最大冲蚀速率均值主效应分析结论一致,验证了正交试验结论的准确性.结论 径向流速、切向流速、管壁压力、最大冲蚀速率为衡量变径T型流道冲蚀程度的指标时,入口流速的影响最大,其次是支撑剂粒径、变径比、砂比,入口流速与其他因素的交互作用对冲蚀速率的影响最显著.

Research on Erosion Characteristics of Variable Diameter T-shaped Flow Channel Based on CFD-DEM Method

In the process of oil exploitation, sand-carrying fracturing fluid''s erosion and abrasion law and main influencing factors of the wall of the variable diameter T-shaped flow channel are studied. diameter T-channel in oil fracturing manifold and down hole sandblasting tool. A CFD-DEM model for predicting erosion wear of solid-liquid two-phase flow in variable diameter T-channel was established. In this model, a reverse iterative collision search algorithm was adopted for particle-particle and particle-wall collisions, and the time step of particle-fluid coupling calculation was adjusted adaptively according to the coupling convergence conditions. The interaction between the mean main effect response and the change of each factor and the priority of each factor change were analyzed by the combined numerical method and orthogonal test method, and the influence of the change of single factor of erosion method was also studied. In univariate analysis, the maximum erosion rate and erosion area of the T-channel increased with the increase of inlet velocity, and the erosion location moved towards the outlet of the channel. The particle carrying capacity of the fluid increased, and the amount of accumulated particles decreased. In the sand ratio range of 5%~35%, the maximum erosion rate is positively correlated with sand ratio. The maximum erosion rate increases first and then decreases with the change of particle size, and decreases with the increase of diameter ratio. The results are consistent with the main effect analysis of the mean maximum erosion rate, which verifies the accuracy of the orthogonal experiment conclusion. When radial velocity, tangential velocity, pipe wall pressure and maximum erosion rate are the indexes to measure the erosion degree of variable diameter T-channel, inlet velocity has the greatest influence, followed by proppant particle size, variable diameter ratio and sand ratio. The interaction between inlet velocity and other factors has the most significant influence on erosion rate.