承插式90°弯头水力特性的试验与数值模拟

Experimental and Numerical Simulation Study on Hydrodynamic Characteristics of 90° Elbow

为了研究弯头水流阻力及水流流动特征,运用试验和数值模拟的方法,对DN50和DN75 2种PVC承插式90°弯头的流动特性进行了试验和数值模拟,所得模拟结果与试验结果基本吻合。结果表明:不同管径的弯头局部阻力系数先随雷诺数的增大而迅速降低,在雷诺数达到一定数值后,局部阻力系数趋于一定值,随雷诺数的变化很小。利用CFD中的fluent软件,对不同管径的承插式90°弯头进行了数值模拟。根据模拟结果,建立了局部阻力系数与管径的关系式。同时对比分析了承插式90°弯头的速度场、压力场,由弯头的流线图和速度矢量图,得出了弯头能量损失的主要原因:弯头的能量损失主要发生在弯头下游管段,弯头水头损失主要来源于因流动方向的改变及漩涡引起的能量损失。

In order to study the flow resistance and water flow characteristics of elbow, a series of experiments and numerical simulation of water flow in two kinds of PVC 90 °socket elbows, including DN75 and DNS0, and their flow characteristics are studied in this paper. The simulation results are consistent with the test results. The results show that the local resistance coefficient in different pipe diameter of elbow firstly drops quickly with the increase of Reynolds number, white the change with Reynolds number is very small when the Reynolds number reaches a certain value. The flow characteristic in the elbow is then studied by using the CFD software. Based on the simulation results, the relation function between the local resistance coefficient and the pipe diameter is established. Meanwhile, by comparing and analyzing the 90°socket elbow velocity field and pressure field, the main reason for the bend energy loss is gained from the elbow flow diagram and the velocity vector diagram, which is that energy loss occurs mainly in the elbow downstream section and the head loss mainly because of the change of flow direction and vortex.