深井泵不同转速下性能的数值计算与试验研究

发布时间：2018-05-28 09:10

本文选题：深井泵 + 数值计算　；参考：《江苏大学》2017年硕士论文

【摘要】：作为一种提供高扬程液体的通用机械,深井泵已被广泛应用于国民经济和社会生产的各个领域。由于泵体外径受到井径的限制,深井泵大多采用增加级数的方法来满足总扬程的需求,这会导致其轴向长度较大,因而给深井泵的安装与维修带来不便。为了提高深井泵的单级扬程、缩短其轴向长度,提高其运行转速已成为深井泵设计的一大趋势。本文以UG 8.0、ANSYS CFX 14.5等软件为工具,完成了100QJ20型高速深井泵的水力设计与数值计算,并通过性能试验验证了数值计算的准确性。主要研究内容与取得的研究成果如下:(1)回顾了深井泵产品的发展历史,对其水力设计的相关研究做了简单的总结,并介绍了近年来泵内部流动与泵转速变化的研究现状。(2)基于等比例缩放设计法完成了100QJ20型深井泵的水力设计,并对初始模型(150QJ36型深井泵)与设计模型分别进行了三维建模与各计算域的网格划分,采用ANSYS CFX软件分别完成了两组模型的数值计算。两组模型的外特性在0.4~1.6倍额定流量工况范围内基本满足相似换算准则,其内部流场的分布规律具有较强的相似性与微小的差异性。对150QJ36型深井泵进行了性能试验,结果表明数值预测扬程与功率略低于试验结果,预测的效率略高于试验值,但整体上两者随流量的变化趋势基本一致,证实本文的数值模拟具有较高的精度。(3)对100QJ20型深井泵分别在三种不同转速方案下进行了多工况数值计算,分析了运行转速对深井泵性能的影响。结果表明不同转速下的深井泵扬程、功率预测值基本满足相似换算准则,泵效率则随着转速的提高而有所提升。这是由于不同转速下泵内的圆盘摩擦损失不符合相似换算准则而造成的,随着转速的提高,圆盘摩擦损失在轴功率中所占的比重不断下降。(4)在深井泵模型各计算子域中布置了多组监测点,完成了对深井泵模型在3种不同转速下的非定常数值计算,获取了各监测点的压力脉动数据。通过对压力脉动数据的无量纲处理与快速傅里叶变换,获得了压力脉动时域分布和频域分布,对比发现泵内压力脉动存在较为复杂的级间耦合与拍振现象。不同转速下泵内压力脉动的分布规律具有一定的相似性,但高转速下泵内压力脉动的主频频率要高于低转速下的,且转速的变化会引起某些监测点压力脉动相位的改变。(5)确定了三种不同的转速变化方式,并以此完成了不同转速变化方式下深井泵模型的非定常数值计算。在三种方案中,直线加速过程与开口向下的二次加速过程中,扬程的波动要弱于开口向上的二次加速过程,且开口向下的二次加速过程能够最先达到扬程要求;在泵加速过程中,叶轮流道内的二次流会得到明显的改善。
[Abstract]:As a kind of universal machinery to provide high head liquid, deep well pump has been widely used in various fields of national economy and social production. Because the outer diameter of pump body is limited by the well diameter, most deep well pumps adopt the method of increasing series to meet the demand of total head, which will lead to the large axial length of pump, which brings inconvenience to the installation and maintenance of deep well pump. In order to improve the single stage head of deep well pump, shorten its axial length and improve its running speed, it has become a major trend in the design of deep well pump. In this paper, the hydraulic design and numerical calculation of 100QJ20 type high speed deep well pump are completed with the software of UG 8.0 and ANSYS CFX 14.5, and the accuracy of numerical calculation is verified by performance test. The main research contents and results obtained are as follows: (1) reviewing the development history of deep well pump products, and briefly summarizing the relevant research on hydraulic design of deep well pumps. The research status of pump internal flow and pump speed change in recent years is introduced. The hydraulic design of 100QJ20 deep well pump is completed based on the equal scale scaling design method. The initial model and the design model are modeled and meshed in each computing domain respectively. The numerical calculation of the two groups of models is completed by using ANSYS CFX software. The external characteristics of the two groups of models basically meet the similar conversion criterion in the range of 0.4 ~ 1.6 times rated flow rate, and the distribution law of internal flow field has strong similarity and small difference. The performance test of 150QJ36 type deep well pump is carried out. The results show that the predicted head and power are slightly lower than the test results, and the predicted efficiency is slightly higher than the experimental value, but on the whole, the variation trend of the two kinds of pumps with the flow rate is basically the same. It is proved that the numerical simulation in this paper has a high accuracy. The numerical calculation of 100QJ20 deep well pump under three different rotational speed schemes has been carried out, and the effect of running speed on the performance of deep well pump has been analyzed. The results show that the power prediction value of the deep well pump at different rotational speeds basically meets the similar conversion criteria, while the pump efficiency is improved with the increase of the rotational speed. This is caused by the fact that the friction loss of the disk in the pump does not conform to the similar conversion criteria at different rotational speeds, and with the increase of the rotational speed, The proportion of disk friction loss in shaft power is decreasing continuously. (4) multiple monitoring points are arranged in each calculation subdomain of deep well pump model, and the unsteady numerical calculation of deep well pump model under three different rotational speeds is completed. The pressure fluctuation data of each monitoring point are obtained. The time-domain and frequency-domain distributions of pressure pulsation are obtained by dimensionless processing and fast Fourier transform of pressure pulsation data. It is found that there are more complicated phenomena of interstage coupling and beat vibration in pump pressure pulsation. The distribution of pressure pulsation in the pump at different rotational speeds is similar, but the main frequency of the pressure pulsation in the pump at high rotational speed is higher than that at low rotational speed. And the change of rotational speed will cause the change of the phase of pressure pulsation in some monitoring points.) three different rotational speed change modes are determined and the unsteady numerical calculation of the deep well pump model under different rotational speed variation modes is completed. In the three schemes, the fluctuation of the head is weaker than the second acceleration up the opening in the linear acceleration process and the secondary acceleration process down the opening, and the secondary acceleration process down the opening can first meet the requirements of the lift. In the process of pump acceleration, the secondary flow in the impeller passage will be improved obviously.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH38

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