| 王李科,卢金玲,廖伟丽,王维,冯建军,罗兴锜.离心泵叶顶泄漏涡结构特性研究[J].水利学报,2020,51(6):738-748 |
| 离心泵叶顶泄漏涡结构特性研究 |
| Investigation of tip leakage vortex characteristics in a centrifugal pump |
| 投稿时间：2020-03-12 |
| DOI：10.13243/j.cnki.slxb.20200146 |
| 中文关键词: 离心泵 泄漏涡 Omega涡识别准则 前缘溢流 熵产 |
| 英文关键词: centrifugal pump tip leakage vortex Omega vortex identification leading edge over flow entropy production |
| 基金项目:国家自然科学基金面上项目（51879216，51679196，51679195） |
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| 中文摘要: |
| 叶顶间隙产生的泄漏涡会对半开式离心泵性能产生不利影响，为了探究不同流量工况下泄漏涡结构及其运动轨迹的变化规律，本文采用SST k-ω湍流模型对半开式离心泵进行全流道数值模拟，分析了泄漏涡的结构特征和泄漏流速度分布，改进了泄漏涡运动轨迹预测模型。结果表明，数值模拟值得到的外特性与试验值吻合较好；叶顶泄漏流相对速度的弦向分量的最小值出现的位置与泄漏涡的初始位置重合，并且随着流量的减小向上游移动。叶片进口边负的弦向分量导致回流的形成，而法向分量的增大是导致小流量工况前缘溢流和大流量工况叶片尾缘二次泄漏流的根本原因。叶顶间隙内速度梯度较大的泄漏流会引发高熵产，并且与主流混掺形成泄漏涡，在泄漏涡周围同样引发高熵产，高熵产区面积随着流量的减小而增大。改进轨迹预测模型用叶顶间隙进口的平均速度代替了原先叶轮进口平均速度，扩展了预测范围，减小了预测结果的误差，说明改进模型能够很好地预测泄漏涡核的迁移轨迹。 |
| 英文摘要: |
| Tip leakage vortex in a semi-open centrifugal pump has adverse effect on the external performance and vibration. In order to improve the understanding of tip leakage vortex structure and trajectory,a semi-open centrifugal pump was simulated by ANSYS CFX software and SST k-ω turbulence model. Then, the characteristics of the tip leakage vortex and distribution of tip leakage flow were analyzed, the prediction model of the tip leakage vortex trajectory was improved. The results show that the external characteristic of the numerical simulation is consistent with the experiment data. The minimum of the chordwise component of the tip leakage flow relative velocity coincides with the initial position of tip leakage vortex, and it moves upstream with the decrease of flow rate. The negative chordwise component leads to the formation of reverse vortex, and the increase of normal component is the main reason for leading edge overflow at small flow rate and secondary tip leakage flow nearing the trailing edge at the large flow rate. The tip leakage flow with a large velocity gradient at the tip clearance leads to the high entropy production rate. The mixing and rolling up phenomenon between the tip leakage flow and main flow also results in high entropy production rate. The area of the high entropy production rate increases with the flow rate decrease. The improved trajectory prediction model replaces the average velocity of the impeller inlet with the average velocity of the blade tip clearance inlet. The errors between the predicted results and the numerical simulation results are negligible, indicating that the improved model could well predict the migration trajectory and expand the prediction range. |
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