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大涡模拟研究展向旋转槽道湍流流动

Large eddy simulation of spanwise rotating turbulent channel flow

  • 摘要: 本文用大涡模拟预测了以不同转速做展向旋转的槽道湍流流动,统计平均的流向速度型在壁面附近与已有实验数据符合很好,在通道中部的预测差异也能给出合理解释,对比不同转速的计算结果,表明展向旋转通道的湍流应力和壁面摩擦力在压力面附近提高、在吸力面附近降低,这些高阶湍流统计量的变化规律可以结合湍流应力输运方程加以解释,漩涡识别技术显示了近壁条带结构,其形态和猝发率受旋转附加力的影响发生改变,进而影响壁面摩擦速度的数值和分布,进一步考察垂直流动方向的截面内速度分布,发现旋转引起了垂直壁面方向的流动,形成正负相间排列的流向涡对,并随着转速的增加向压力面靠近。

     

    Abstract: Large eddy simulation (LES) is used to predict flow filedin fully developed turbulent channel flow rotating along spanwise axis atsix different angular velocities. Statistically-averaged streamwise velocityprofile consists well with available experimental data near the wall. Thephenomena that turbulence and wall friction are enhanced near pressure sideand depressed near suction side are recovered. Explanation for theevolvement of lower order turbulence correlations is consistent with theanalysis of the transport equation for each turbulence stress component. Thebursting and the shape of near wall streak are also affected by rotationalforces, resulting in variation of wall friction velocity. Furthermore,velocity distribution in streamwise cross section indicates that Coriolisforce induces secondary flow normal to the wall. Such secondary flowgenerates counter rotating vortex pairs in streamwise, which shift towardspressure side as the rotating velocity increases. The results with lowcomputational cost agree with available conclusion, implying possibleapplication of LES for engineering usage.

     

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