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采用大涡模拟方法对直方管内的湍流流动进行了研究,对比计算了进口处为均匀来流和非均匀来流三种工况。从瞬时速度、脉动速度和平均速度分布等方面对湍流流动进行了分析。计算结果表明:入口处均匀来流和非均匀来流在横截面都会产生二次流运动;四个角域强化了壁面流体和主流流体的动量交换;在平均雷诺数相同情况下,非均匀来流时湍流程度大,各方向湍流脉动加强,横截面二次流加强,出现多个复杂的涡流区,瞬时流场结构、涡结构要复杂得多。
The large eddy simulation method was used to study the turbulent flow in the straight tube. The three conditions of uniform inlet flow and non-uniform inlet flow were calculated. The turbulent flow was analyzed from the aspects of instantaneous velocity, pulsation velocity and average velocity distribution. The results show that both the uniform inlet flow and the non-uniform flow produce secondary flow in the cross section. The four angular flow intensifies the momentum exchange between the wall fluid and the main flow. When the average Reynolds number is the same, The degree of turbulence is large at the time of flow, the turbulent pulsation is strengthened in all directions, the secondary flow in the cross section is strengthened, there are many complicated eddy current zones and instantaneous flow field structure, and the eddy structure is much more complex.