基于座头鲸"结节效应"的仿生离心泵空化特性

    Cavitation characteristics of bionic centrifugal pump based on "nodule effect" of humpback whale

    • 摘要: 为了研究离心泵空化抑制策略,改善离心泵的空化特性,该研究基于仿生学中的座头鲸鲸鳍"结节效应"提出了一种仿生离心泵模型。对原型泵和仿生模型的瞬态空化流进行了数值模拟,并使用水力性能和空化性能试验对算法进行验证,分析了原型泵和仿生模型的外特性和空化特性,以及叶轮流道内空泡发展、压力脉动、涡量场、压力分布、湍动能分布情况。结果表明:数值模拟结果与试验结果吻合较好,仿生结构对原型泵水力性能影响较小,扬程变化范围为:-0.73%~0.77%,效率变化范围为:-1.74%~2.52%;仿生模型有效抑制了空泡发展,减少了空泡体积,在空化初生阶段抑制效果最好,平均空泡体积分数减少99.72%,仿生模型较原型泵的空化特性得到改善,提高了原型泵的水力性能;仿生模型降低了离心泵内多个位置的压力脉动主频幅值;仿生结构处产生的对漩涡会改变叶轮涡量场,使叶轮进口低压区减少的同时降低了叶轮流道内的湍动能,达到抑制空化发生和限制空化发展的作用。仿生模型可以有效地抑制离心泵空化的发生,改善离心泵的空化性能。

       

      Abstract: Abstract: This study aims to determine the cavitation suppression strategy of centrifugal pump for the better cavitation performance of centrifugal pump. A bionic centrifugal pump model was also proposed using the bionic humpback whale fin "nodule effect". The modified SST k-ω Turbulence Model and Z-G-B cavitation model were used to simulate the transient cavitation flow of the prototype pump. The bionic model was verified by the hydraulic performance and cavitation performance tests. A systematic analysis was made to clarify the external and cavitation characteristics of the prototype pump and bionic model, as well as the cavity development, pressure fluctuation, vorticity field, pressure distribution, and turbulent kinetic energy distribution in the impeller channel. The results show that the numerical simulation was in an excellent agreement with the experimental data, where there was the little effect of bionic structure on the hydraulic performance of the prototype pump. The variation ranges of head and efficiency were -0.73%-0.77%, and -1.74%-2.52%, respectively. There was the variation in the cavitation characteristics of the bionic model for the better hydraulic performance of the prototype pump that caused by cavitation. There was the most outstanding fracture cavitation stage, where the fracture head under NPSHa=0.049 working condition increased from 3.59 to 4.01 m, indicating the increase of 11.7%. The bionic model was effectively inhibited the development of cavity for the less volume of cavity. There was the best inhibition effect in the initial stage of cavitation, and the average volume fraction of cavity was reduced by 99.72%. The main frequency of pressure fluctuation in the original model occurred at the blade passing frequency of 50 Hz. There was no change in the bionic model for the main frequency characteristics of pressure fluctuation of the original model. The bionic model was effectively reduced the main frequency amplitude of the pressure fluctuation at the volute tongue, the blade inlet, and the impeller channel outlet, while the disturbance of the bionic nodule flow field made the flow in the middle of the impeller channel unstable, where the main frequency amplitude of the pressure fluctuation increased significantly. The bionic model was also reduced the main frequency amplitude of pressure fluctuation at the multiple positions in the centrifugal pump. The decrease of pressure fluctuation indicated that the cavitation noise and cavitation surge were also suppressed in the centrifugal pump. The counter vortex that generated at the bionic structure was changed the impeller vorticity field for the high-intensity vorticity area in front of the bionic nodule and near the wall of the leading edge of the blade. The anti-interference performance of the blade was improved to make the cavity development more stable. The high-intensity vorticity area was also reduced at the inlet of the impeller channel for the more uniform flow in the impeller channel. The bionic model was reduced the area of the low-pressure area at the impeller inlet and the turbulent kinetic energy in the impeller passage, leading to the less cavitation and the flow loss. The bionic model can be expected to effectively inhibit the cavitation of centrifugal pump for the better performance of centrifugal pump.

       

    /

    返回文章
    返回