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Numerical study on the effect of tangential intake on vortex dropshaft assessment using pressure distributions
Engineering Applications of Computational Fluid Mechanics ( IF 6.1 ) Pub Date : 2022-05-12 , DOI: 10.1080/19942060.2022.2072954
Lu Chang, Wangru Wei

Dropshafts with tangential intakes are common structures in urban water drainage systems. The plunging and vortex flowpatterns are the typical flow regimes, which are mainly affected by the tangential intake design and flood discharge. However, thehydraulic flow transition between vortex and plunging flow patterns has received little attention, which may affect the dropshaftoperation during extreme flood discharge events. In this study, the effects of the flow discharge and contraction ratio on the pressuredistributions of vortex dropshafts are analysed based on a series of numerical simulations. The pressure distributions of the plungingand vortex flow patterns are compared; two hydraulic factors are used to distinguish rotational and non-rotational dropshaftoperations. For appropriate vortex dropshaft designs, the minimum to maximum wall pressure ratio should be greater than 0.1 at theintake cross-section and greater than 0.2 during the falling process. Based on this principle, flows in the annular dropshaft areclassified into non-rotation, transition, and rotation regimes. The results agree with the theoretical rotation intensity of the vortex flow,and an empirical relation is proposed. The present study is easy to implement and practically useful to assess the vortex dropshaftdesign for local water drainage systems.



中文翻译:

使用压力分布的切向进气对涡垂轴评估影响的数值研究

具有切向进水口的吊轴是城市排水系统中的常见结构。切入式和涡旋流型是典型的流态,主要受切向进水口设计和泄洪影响。然而,涡流与突进流型之间的水力流动过渡很少受到关注,这可能会在极端泄洪事件中影响下垂轴的运行。在这项研究中,基于一系列数值模拟分析了流量和收缩比对涡旋下垂轴压力分布的影响。比较了俯冲和涡流模式的压力分布;两个液压因素用于区分旋转和非旋转下落轴操作。对于适当的涡旋下落轴设计,进水断面最小与最大壁压比应大于0.1,下降过程中应大于0.2。基于这一原理,环形下落轴中的流动分为非旋转、过渡和旋转状态。结果与涡流的理论旋转强度一致,并提出了经验关系式。本研究易于实施,对评估当地排水系统的涡流下降轴设计具有实际意义。并提出了一个经验关系。本研究易于实施,对评估当地排水系统的涡流下降轴设计具有实际意义。并提出了一个经验关系。本研究易于实施,对评估当地排水系统的涡流下降轴设计具有实际意义。

更新日期:2022-05-12
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