半开式离心泵汽蚀特性及数值模拟研究

发布时间：2018-11-09 12:47

【摘要】：随着国民经济的发展,离心泵的应用领域越来越广泛,但是汽蚀这一难题导致其性能下降、损失增大,不仅影响了离心泵的工作稳定性和可靠性,而且浪费了很多能量,所以研究离心泵的汽蚀有重要意义。本文使用自行搭建的可视化半开式离心泵实验台,分别进行了离心泵的性能实验和汽蚀实验,在实验基础上使用ANSYS软件对实验泵进行建模,并进行了内流场、汽蚀的数值模拟,与实验的结果相印证。最后分析了叶顶间隙、动静叶相互作用对离心泵汽蚀的影响。主要工作如下:1、搭建可视化半开式离心泵实验台进行离心泵的性能实验和汽蚀实验,绘制出离心泵性能曲线,采用高速摄像技术拍摄汽蚀现象,拍摄结果显示汽蚀发生的位置位于离心泵动叶进口吸力面。根据实验离心泵的几何参数建立三维模型,使用CFX进行离心泵的内流场模拟,将性能曲线与实验数据对比,误差在10%以内。2、模拟汽蚀情况下不同流量工况离心泵的压力场分布和气体体积分数分布,并绘制了汽蚀余量-扬程曲线和汽蚀余量-流量曲线。结果表明:汽蚀一般率先发生在离心泵动叶进口吸力面偏后位置,随着汽蚀的加深汽蚀发生区域沿动叶的流线方向发展,这与实验所拍摄的结果相符合。随着流量的增大,汽蚀发生的工况提前,即发生汽蚀时进口压力的值增大。3、分析了叶顶间隙和动静叶相互作用对离心泵汽蚀性能的影响。首先对不同叶顶间隙下离心泵的汽蚀进行分析,绘制了额定流量下不同叶顶间隙的NPSHH曲线,找到汽蚀临界点,结果表明,在一定范围内,随着叶顶间隙的增大,离心泵的扬程下降,并且越容易发生汽蚀。然后分析了动静叶相互作用对离心泵性能的影响,然后分析了动静叶不同相对位置时的气体体积分数分布以及叶片载荷的分布。结果表明,随着叶轮的转动,离心泵性能、压力场的分布、气体体积分布的分布都呈周期性变化,汽蚀发生的区域在动叶前段至1/5长度处。
[Abstract]:With the development of national economy, the application of centrifugal pump is more and more extensive, but the cavitation problem leads to its performance decline and loss increase, which not only affects the working stability and reliability of centrifugal pump, but also wastes a lot of energy. So it is important to study cavitation of centrifugal pump. In this paper, the performance experiment and cavitation experiment of the centrifugal pump are carried out by using the visual semi-open centrifugal pump test bench built by ourselves. On the basis of the experiment, the experimental pump is modeled with ANSYS software, and the numerical simulation of the internal flow field and cavitation erosion is carried out. The results are in agreement with the experimental results. Finally, the effects of tip clearance and dynamic and static blade interaction on cavitation of centrifugal pump are analyzed. The main work is as follows: 1. Build a visual semi-open centrifugal pump test bench for centrifugal pump performance experiment and cavitation experiment, draw the centrifugal pump performance curve, use high-speed camera technology to photograph cavitation phenomenon, The results showed that the cavitation occurred on the suction surface of centrifugal pump. According to the geometric parameters of the experimental centrifugal pump, the three-dimensional model is established, and the internal flow field of the centrifugal pump is simulated by using CFX. The performance curve is compared with the experimental data and the error is less than 10%. The pressure field distribution and gas volume fraction distribution of centrifugal pump with different flow conditions were simulated and the cavitation residual-lift curves and cavitation residual-flow curves were plotted. The results show that cavitation generally occurs first in the inlet suction surface of centrifugal pump and develops along the flow line of the moving blade with the deepening of cavitation, which is consistent with the experimental results. With the increase of flow rate, the cavitation occurs in advance, that is, the inlet pressure increases when cavitation occurs. 3. The influence of blade tip clearance and dynamic and static blade interaction on cavitation performance of centrifugal pump is analyzed. Firstly, the cavitation of centrifugal pump with different blade top clearance is analyzed, the NPSHH curve of different blade top clearance under rated flow rate is drawn, and the cavitation critical point is found. The results show that the cavitation critical point increases with the increase of blade top clearance in a certain range. The head of the centrifugal pump drops, and the more prone to cavitation. Then the influence of the interaction of the stator and the stator on the performance of the centrifugal pump is analyzed, and the distribution of the volume fraction of gas and the load distribution of the blade at different relative positions are analyzed. The results show that with the rotation of impeller, the performance of centrifugal pump, the distribution of pressure field and the distribution of gas volume change periodically, and the region of cavitation occurs from the front of the blade to a fifth of the length of the blade.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH311

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