Numerical Simulation of Cavitating Flow in Mixed Flow Pump With Closed Type Impeller
Numerical Simulation of Cavitating Flow in Mixed Flow Pump With Closed Type Impeller
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DOI：
10.1115/fedsm2009-78308
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
Katsutoshi Kobayashi;Y. Chiba
中科院分区：
文献类型：
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作者：
Katsutoshi Kobayashi;Y. Chiba
采用基于空化模型的大涡模拟方法对闭式叶轮混流泵的非定常流场进行了计算。首先，对数值结果和实验结果进行了比较，以评估计算精度。其次，通过仿真计算作用在叶片上的转矩，研究空化对转矩波动的影响。在数值和实验结果中，叶片吸力面前缘附近的绝对压力均出现正脉冲峰。模拟结果表明，这些峰是由前缘附近的空化收缩和消失引起的。通过模拟预测绝对压力，误差为- 10%。在叶片吸力面尾缘附近的绝对压力在数值和实验结果中都没有出现脉冲峰，因为绝对压力比饱和蒸汽压高100倍。仿真结果表明，气穴在喉部周围产生，然后收缩，最后消失。模拟的泵具有5个喉道，在5个喉道附近的收缩和消失等空化行为是不同的。例如，这五个喉部周围的空化并没有同时消失。当空化收缩并最终消失时，叶片表面的绝对压力增大。当空化在位于叶片表面压力侧的喉部周围收缩时，叶片表面压力侧的压力变高。它使转矩的脉冲峰值比平均值高1.4倍。另一方面，当空化在位于叶片吸力侧的喉部周围收缩时，叶片吸力侧的压力变大。它使转矩的脉冲峰值比平均值低0.4倍。喉部周围的空化导致作用在叶片上的扭矩波动较大。ASME版权所有©2009
LES (Large Eddy Simulation) with a cavitation model was performed to calculate an unsteady flow for a mixed flow pump with a closed type impeller. First, the comparison between the numerical and experimental results was done to evaluate a computational accuracy. Second, the torque acting on the blade was calculated by simulation to investigate how the cavitation caused the fluctuation of torque. The absolute pressure around the leading edge on the suction side of blade surface had positive impulsive peaks in both the numerical and experimental results. The simulation showed that those peaks were caused by the cavitaion which contracted and vanished around the leading edge. The absolute pressure was predicted by simulation with −10% error. The absolute pressure around the trailing edge on the suction side of blade surface had no impulsive peaks in both the numerical and experimental results, because the absolute pressure was 100 times higher than the saturated vapor pressure. The simulation results showed that the cavitation was generated around the throat, then contracted and finally vanished. The simulated pump had five throats and cavitation behaviors such as contraction and vanishing around five throats were different from each other. For instance, the cavitations around those five throats were not vanished at the same time. When the cavitation was contracted and finally vanished, the absolute pressure on the blade surface was increased. When the cavitation was contracted around the throat located on the pressure side of blade surface, the pressure became high on the pressure side of blade surface. It caused the 1.4 times higher impulsive peak in the torque than the averaged value. On the other hand, when the cavitation was contracted around the throat located on the suction side of blade surface, the pressure became high on the suction side of blade surface. It caused the 0.4 times lower impulsive peak in the torque than the averaged value. The cavitation around the throat caused the large fluctuation in torque acting on the blade.Copyright © 2009 by ASME