改良楔形叶片旋转空化器水动力学特性数值模拟分析

Numerical analysis of hydrodynamic characteristics of rotational cavitator with improved wedge-shaped blade

  • 摘要:
      目的  旋转空化器是通过高速旋转的叶片在水中产生超空泡来满足不同工程实际应用需求,有必要对叶片形状进行改良设计以提高其工作性能,探究叶型改良对空化器水动力学特性的影响。
      方法  首先,针对旋转空化器楔形叶片的原始叶型进行改良设计,建立叶片改型前、后旋转空化器的三维几何模型;然后,基于ANSYS Fluent软件对原始叶型和改良叶型空化器在不同转速下的自然空化流场开展数值仿真计算;最后,根据计算结果对二者的水动力学特性进行对比分析。
      结果  结果显示,相比原始叶型,改良叶型产生的空泡除存在于叶片出口边外,还可以存在于副进口边,这两部分的空泡会随着转速的升高而逐渐连接成一个整体,因而改良叶型空化器产生的空泡尺寸更大,产生的自然空化更强;改良叶型在叶根处产生的空化效应较强,而原始叶型在叶尖处产生的空化效应更强;当转速较高时,改良叶型产生的空泡会与旋转空化器装置的四周壁面接触,导致空泡尾部形态沿半径呈直线型变化。
      结论  所做研究可为旋转空化器的设计和应用提供重要参考。

     

    Abstract:
      Objectives  A rotational cavitator generates supercavitation through the high-speed rotation of its blades in water to meet the practical application requirements of various projects. Therefore, it is necessary to optimize the blade profile in order to improve the working performance, and investigate the influence of the improvement of the blade profile on the hydrodynamic characteristics of the cavitator.
      Methods  First, the original wedge-shaped blade is modified, and 3D geometric models of the cavitator before and after the modification are established. Numerical simulations are then carried out of the natural cavitation generated by two cavitators at different rotational speeds. Finally, the hydrodynamic characteristics of the two cavitators are compared and analyzed according to the calculation results.
      Results  The results show that with the original blade profile, the cavity is only generated by the trailing edge, but with the improved blade profile, the cavity can be also generated by the secondary leading edge, and the two cavities are gradually connected with increasing rotational speed. Therefore, the rotational cavitator with the improved blade profile produces a larger cavity and stronger natural cavitation. In addition, with the improved blade profile, the cavitation effect is relatively stronger at the blade root, while with the original blade profile, it is stronger at the blade tip. The cavity generated by the cavitator with the improved blade profile at higher rotational speed touches the surrounding wall of the device, resulting in a linear change in the shape of the cavity tail along the radius.
      Conclusions  The results of this study can provide important references for the design and application of rotational cavitators.

     

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