Earlier studies have shown that the power consumption of an unbaffled stirred vessel decreases significantly when the regular blades are replaced by fractal ones. In this paper, the physical explanation for this reduction is investigated using Direct Numerical Simulations at Re = 1600. The gaps around the fractal blade perimeter create jets that penetrate inside the recirculation zone in the wake and break up the trailing vortices into smaller ones. This affects the time‐average recirculation pattern on the suction side. The volume of the separation region is 7% smaller in the wake of the fractal blades. The lower torque of the fractal impeller is equivalent to a decreased transport of angular momentum; this difference stems from the reduced turbulent transport induced by the smaller trailing vortices. The major difference in the turbulent dissipation is seen in the vicinity of trailing vortices, due to fluctuations of velocity gradients at relatively low frequencies. © 2018 American Institute of Chemical Engineers AIChE J, 64: 1485–1499, 2018

中文翻译：

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通过分形叶轮减少搅拌容器中的功率消耗

早期的研究表明，当用分形叶片代替常规叶片时，无挡板搅拌容器的功耗会显着降低。在本文中，使用Re = 1600处的直接数值模拟研究了这种减小的物理解释。分形叶片周长周围的间隙产生了射流，这些射流穿透尾流中的再循环区域，并将尾随的涡旋分解成较小的涡旋。这会影响吸入侧的时间平均再循环模式。分形叶片之后，分离区域的体积减小了7％。分形叶轮的较低扭矩相当于减少了角动量的传递。这种差异源于较小的尾随涡流引起的湍流传输减少。。©2018美国化学工程师学会AIChE J，64：1485–1499，2018