Investigation of the Dynamical Behaviour of Trailing Vortices in Unba ed Stirred Vessels at Transitional Reynolds Numbers
Investigation of the Dynamical Behaviour of Trailing Vortices in Unba ed Stirred Vessels at Transitional Reynolds Numbers
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过渡雷诺数下无基底搅拌容器中尾随涡流动力学行为的研究
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
J. C. Vassilicos
中科院分区：
文献类型：
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作者：
S. Ba;G. Papadakis;J. C. Vassilicos
采用直接数值模拟（DNS）方法研究了Re = 320和1600时无底艾德搅拌槽内的流场。我们观察到在功率消耗中的波动，峰值频率在ca。两个雷诺数的叶轮转速的三倍。研究发现，这些脉动与叶片尾流中的周期性事件有关，包括尾涡对上下涡核的交替增长和衰减以及径向射流的上下摆动。此外，还详细分析了不同叶片尾迹之间的相位关系。使用分形形状叶片的进一步研究表明，确切的叶片形状对这种现象没有很大影响。然而，叶片之间的尾流相互作用，从而叶片的数量，有一个直接的尾涡的非定常性的影响。
Flow in an unba ed stirred vessel agitated by a four-bladed radial impeller is investigated by using Direct Numerical Simulations (DNS) at Re = 320 and 1600. We observe uctuations in the power consumption with a peak frequency at ca. three times the impeller rotational speed for both Reynolds numbers. It is discovered that these uctuations are associated with a periodic event in the wake of the blades, which involves alternating growth and decay of the upper and lower cores of the trailing vortex pair as well as up-and-down swinging motion of the radial jet. Moreover, the phase relation between the wakes of the di erent blades is examined in detail. Further studies using fractal-shaped blades show that the exact blade shape does not have a strong in uence on this phenomenon. However, the wake interaction between the blades, hence the number of blades, has a direct in uence on the unsteadiness of trailing vortices.