加装旋转叶片T型通道内流动混合的数值模拟

Numerical Simulation of the Mixing Behavior in the T-junction With a Rotating Impeller

本文采用大涡模拟方法对加装旋转叶片的T型通道内冷热流体流动混合过程进行了数值模拟研究。在主管支管管径比为2:1的条件下,探究旋转叶片对T型通道内冷热流体混合的影响机理。通过对比分析有无叶片的T型通道内温度场,发现加装旋转叶片能够加快通道底部和对称面两侧流体的温度混合从而缩短通道内的混合长度,同时能够减小y轴方向的平均温度梯度进而改善通道内的热分层现象。为进一步分析旋转叶片在T型通道内的作用方式,本文获取了叶片旋转至不同角度下T型通道内的速度场和涡结构分布,结果表明加入旋转叶片后通道内出现了马蹄涡、叶尖分离涡和条状涡等涡结构,加剧了流动的不规则性。

The mixing process of cold and hot fluids in the T-junction with an impeller is studied by large eddy simulation method. Under the diameter ratio of main and branch pipe of 2 : 1, the influence mechanism of the impeller on the mixing behavior of cold and hot fluid in the T-junction is explored. By comparing and analyzing the temperature field in the T-junction with or without the impeller, it is found that by adding an impeller in the T-junction the length of mixing zone is shortened because the temperature mixing at the bottom of the pipe and on both sides of the symmetry plane is accelerated, at the same time temperature gradient in the y-axis direction is reduced so as to break the thermal stratification in the pipe. To further analyze the mechanism of the rotation impeller in the T-junction, the velocity field and vortex structure distribution in the T-junction are obtained at different angles, the results show that there is horseshoe vortex, tip separation vortex and strip vortex in the pipe, which increase disturbance of the flow.