液固两相流盲三通冲蚀特性数值分析

Numerical Analysis on Erosion Characteristics of Blind Tee in Liquid-solid Two-phase Flow

盲三通内特殊的"气垫"结构可以在节省空间的同时提升管道的抗冲蚀性能。为了分析液固两相流环境下弯管和盲三通内的流场分布,并对比其抗冲蚀性能,分析冲蚀机理,运用CFD-DPM方法对相同直径弯管和盲三通内的流场进行了数值计算。通过对几何模型进行网格无关性验证来确定最佳的网格数量,选用Realizable k-ε湍流模型、McLaury冲蚀预测模型和Forder壁面反弹恢复模型来计算冲蚀速率。分析结果显示:盲三通的最大冲蚀速率明显低于弯管;弯管的主要冲蚀部位位于中心区域的外侧壁面,盲三通的冲蚀区域主要位于相贯线附近和出料管底部;在盲三通内存在缓冲涡,可以阻止固体颗粒对壁面的直接撞击,从而减轻对管道的冲蚀;随着流体流速的增加,冲蚀逐渐加重,且流速较高时,冲蚀速率增加幅度越大;随着颗粒质量流量的增加,冲蚀速率呈线性增加,增长斜率随长径比的增大而减小。所得结果对于管道的设计选用及长周期安全运营有一定的参考价值。

The special “air cushion” structure in the blind tee can improve the erosion resistance performance of the pipe at the same time of saving space. In order to analyze the flow field distribution in elbow and blind tee under the liquid-solid two-phase flow environment, compare their erosion resistance performance and analyze the erosion mechanism, the CFD-DPM method was used to conduct numerical calculation on the flow field in elbow and blind tee with the same diameter. The geometric model was used to conduct grid independence verification to determine the optimal number of grids, and the Realizable k-ε turbulence model, McLaury erosion prediction model and Forder wall rebound recovery model were used to calculate the erosion rate. The analysis results show that the maximum erosion rate of the blind tee is obviously lower than that of the elbow;the main erosion part of the elbow is located on the outer wall of the central area, and the erosion area of the blind tee is mainly located near the intersecting line and at the bottom of the discharge pipe;there is a buffer vortex in the blind tee, which can prevent the direct impact of solid particles on the wall, and thus alleviate the erosion of the pipeline;as the flow rate of fluid increases, the erosion gradually aggravates, and the higher the flow rate, the greater the erosion rate increase;as the particle mass flow rate increases, the erosion rate increases linearly, and the growth slope decreases with the increase of length/diameter ratio. The research results have certain reference value for the design, selection and long-term safe operation of pipelines.