Direct numerical simulations are used to investigate the Open Von Kármán Swirling Flow, a new type of unsteady three-dimensional flow that is formed between two counter-rotating coaxial disks with an axial extraction enclosed by a cylinder chamber. Solution verification shows that monotonic convergence is achieved on three systematically refined grids for average pressure at the disk periphery with a small grid uncertainty at 3.5%. Effects of the rotational speeds and flow rates on the flow field are examined. When the disks are rotating at the lowest speed, ±100 RPM, only circular vortices are formed regardless of the flow rates. When the disks are rotating at ±300 RPM and ±500 RPM, negative spiral vortex network is formed. The radial counterflow concept for such spiral vortex network is verified by examining various horizontal cuts and radial velocity component, which show radial outflows in two bands near the two disks and radial inflow in one band between them. Overall, the flow is similar to the Stewartson type flow but with significant differences for all three velocity components due to the axial suction at the upper disk center and gap between the disk periphery and chamber wall.

中文翻译：

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开式冯·卡尔曼旋流的直接数值模拟

直接数值模拟用于研究开放式VonKármán旋流，这是一种新型的非定常三维流，它在两个反向旋转的同轴圆盘之间形成，轴向抽出被气缸腔包围。解决方案验证表明，在三个系统精化的网格上，对于磁盘外围的平均压力实现了单调收敛，而网格不确定性很小，为3.5％。研究了转速和流速对流场的影响。当圆盘以最低速度±100 RPM旋转时，无论流速如何，都只会形成圆形漩涡。当磁盘以±300 RPM和±500 RPM旋转时，会形成负螺旋涡旋网络。通过检查各种水平切口和径向速度分量，验证了这种螺旋涡旋网络的径向逆流概念，这些水平切口和径向速度分量显示了在两个圆盘附近的两个带中的径向流出和在两个圆盘之间的一个带中的径向流入。总体而言，该流量类似于Stewartson型流量，但是由于三个较高的速度分量，在上盘中心的轴向吸力以及盘外围与腔室壁之间的间隙，使流量有明显差异。