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采用标准k-ε模型对90°弯管内部流场进行了三维数值模拟研究。模拟中弯管曲率半径与管径之比β=R/d分别为2.0、2.5、3.0和3.5,表观液速为0.5m/s。通过建模和数值计算,研究了弯管内流场分布、压力分布以及速度矢量和流动轨迹等规律,并重点分析了不同β情况下的弯管中流场流动特点。结果表明:流体速度在弯管内不同截面内是逐渐变化的。由于离心力的作用,在流动后段出现二次流,加强了流体的扰动。同时,流体进入弯道后管道内部不同半径处压力不同,弯管内壁面附近处压力较小,弯管外壁面处压力较大。不同曲率半径与直径之比对管内流速分布有较大影响。β由小增大时,内侧流速逐渐变小,实际的管道设计与施工中尽量使用β较大的弯头附件以降低对管道内壁的冲击。
The standard k-ε model was used to study the three-dimensional numerical simulation of flow field inside a 90 ° elbow. The ratio of radius of curvature to diameter of pipe in the simulation β = R / d was 2.0, 2.5, 3.0 and 3.5, respectively, and apparent velocity was 0.5 m / s. Through the modeling and numerical calculation, the law of flow field distribution, pressure distribution, velocity vector and flow trajectory in curved pipe are studied, and the characteristics of flow field in curved pipe under different conditions are analyzed. The results show that the fluid velocity changes gradually in different sections of the elbow. Due to the centrifugal force, a secondary flow appears in the back flow section, which intensifies the fluid disturbance. At the same time, the pressure at different radius inside the pipe after the fluid enters the curve is different, the pressure near the inner wall of the elbow is smaller, and the pressure at the outer wall of the elbow is larger. The ratio of radius of curvature to diameter has a great influence on the velocity distribution in the tube. β increases from small to small, the inner flow rate gradually becomes smaller, the actual pipe design and construction try to use larger elbow attachment to reduce the impact on the pipe wall.