论文总字数：51655字

摘 要

离心泵广泛应用于工业、民用、建筑给排水、暖通、制冷、排污、消防以及化工、制药等领域,其内部流动特征直接影响离心泵的工作性能。为了达到对离心泵性能的需求，扩大离心泵的使用范围，通常对离心泵叶轮外径采取切割的方式。离心泵叶轮外径经过切割之后叶轮几何参数发生了变化，使得其内部流动与原型泵相比存在一定的差异。本文以原油调和250ys150型离心泵为研究对象,采用理论分析和数值模拟技术，研究了该离心泵叶轮切割前后离心泵内部流动特性。对离心泵叶轮切割前后的各性能参数进行了分析对比，讨论了离心泵叶轮外径切割后的离心泵性能的变化。研究结果对离心泵的结构优化和离心泵的节能增效有参考价值。

论文主要研究工作和结论如下：

(1）基于离心泵的基本性能曲线，采用水—油转换技术，研究离心泵输送原油时的性能换算方法。并基于性能换算方法，对原油调和250ys150离心泵进行了性能换算，得到了原油调和250ys150离心泵的性能曲线；

(2)研究离心泵内部流场分析所运用的数值计算理论和方法，基于离心泵的水利模型，采用CAD和Solid works 软件对原油调和250ys150离心泵的叶轮和蜗壳进行造型，建立了离心泵数值模拟计算模型；

（3）利用FLUENT软件模拟计算在定工况、不同切割量下，研究离心泵内部湍流流场的速度、压力分布情况，揭示其在设计工况下的流体流动规律。

(4) 计算结果表明，液体在离心泵叶轮进口处流动比较均匀，速度比较低，进入叶轮后沿径向方向液体速度逐渐升高，到叶轮出口附近达到最大；

(5) 结果表明，从离心泵叶轮进口到叶轮出口，再从蜗壳进口到蜗壳出口，压力沿着液体流动的方向呈逐步增大的趋势，在蜗壳出口附近压力达最大。在叶轮通道内，液体在运动的过程中，压力和速度是不断增加的；在蜗壳内，液体沿着逆时针方向运动到离心泵出口的过程中，速度是逐渐减小的，而此时压力的变化过程是逐渐增大的；

(6)结果表明,离心泵盖板侧流体的速度沿叶轮进口到叶轮出口径向方向逐渐增加。叶轮盖板入口附近流体有严重的旋涡存在，并且旋涡的方向与叶轮的旋转方向相反；叶轮进口靠近叶片吸力面处存在着易发生汽蚀的低压区；在相同半径上，叶片压力面的速度和压力均比吸力面的速度和压力要大；

(7)结果表明,切割前后叶轮内静压分布规律相似，叶轮出口及蜗壳内流动差异较大，流动不相似，且随着切割量的增大，压力分布越来越不均匀。30mm切割量时，静压动压分布较好，切割前后各流道矢量分布相似。切割后叶轮内部各流道压力分布更加均匀，速度小于切割前的速度，性能有所提高。

关键词：离心泵；数值模拟；性能换算；叶轮切割；内部流动特性

ABSTRACT

Centrifugal pumps are widely used in industrial, civil, architecture, HVAC, refrigeration for drainage, sewage, fire, chemical and pharmaceutical, the internal flow characteristics of a centrifugal pump direct impact on the performance of it. In order to achieve the performance demand of the centrifugal pump, expand the scope of the centrifugal pump, cut the outer diameter of the pump impeller is a way we usually adopted. The Centrifugal pump impeller outside diameter will be changed after the cutting, and make its internal flow compared with prototype pump there are some differences. In this paper, the 250ys150 type centrifugal pump used for petroleum crude mixture was chose as a representative. Based on theoretical analysis and numerical technique and the characteristic curve was studied. Each performance curve was analyzed and compared after being cut.Discussed the performance changes of centrifugal pump after the impeller diameter was cut. The results of the study has a reference value to optimize the structure of centrifugal pump , energy conservation and improve the efficiency of centrifugal pump.

The main work and main conclusions in this paper are obtained as follows:

（1）Based on the performance curve of centrifugal pump , the performance of the centrifugal pump oil conversion method by studying the water and oil conversion technology was studied . Based on performance conversion method, conversion of crude oil mixed 250 ys150 centrifugal pump performance.The oil mixed 250 ys150 centrifugal pump performance curve are obtained;

（2）Based on the basic theories and methods of numerical simulation of internal flow in the centrifugal pump as well as hydraulic model of the impeller and the volute, and using three-dimensional software CAD and Solid works, the geometric models of the impeller and the volute were built. And then, numerical model of centrifugal pump for petroleum crude mixture was established;

（3）Under certain conditions, different cutting quantity,we used FLUENT software to simulate the speed of the turbulence flow of a centrifugal pump, pressure distribution are studied, and the under designed condition of fluid flow pattern are revealed ;

（4）Calculations show that liquid in the impeller inlet flow is uniform, speed is lower, velocity increases after entering the impeller liquid along the radial direction, and achieve maximum near the impeller outlet;

（5）Calculations show that imports from impeller impeller export, exported from the imported to the snail's shell, stress along the direction of liquid flow have been gradually increasing trend, maximum pressure near the volute exit. In the impeller passage,with the liquid moving in the process , pressure and velocity is increased; The counter clock wise direction in the volute, liquid in the process of the centrifugal pump outlet, the speed is gradually reduced, while the pressure change process is gradually increased;

（6）Calculations show that imports to the flat side of the fluid velocity increases along the impeller impeller exit radial direction gradually. Serious vortex impeller cover plate exists near the entrance to the fluid, and the direction of the vortex is opposite to the direction of rotating impeller. The area of impeller inlet near the blade suction surface exists the low pressure area witch cavitation often occurred; On the same radius, the velocity and pressure on blade pressure surface is bigger than witch on the suction surface;

（7）Calculations show that the static pressure distribution are similar after impeller being cut .Flow in the impeller outlet and the volute is difference evidently, the flow is not similar, and with the increase of cutting quantity, pressure distribution is more and more uneven . The static pressure distribution of 30 mm cutting quantity is relatively good. The flow vector distribution is similar after impeller being cut.After being cut,the pressure distribution on the flow channel of impeller become more uniform. Speed is lesser too.Meanwhile the performance is improved;

KEYWORDS: Centrifugal pumps; Numerical simulation; The performance conversion ; Impeller cutting; The internal flow characteristics

目 录

摘要 I

ABSTRACT III

第一章 绪论 1

1.1 引言 1

1.1.1 课题背景 1

1.1.2 本课题研究目的及工程应用价值 2

1.2 离心泵内部流场和数值模拟研究现状 3

1.2.1 离心泵设计研究现状 3

1.2.2 离心泵工况调节研究现状 5

1.2.3 CFD技术应用于离心泵内流场分析的研究 10

1.3 离心泵内部流场数值模拟发展趋势 13

1.4 本文的主要研究内容 14

第二章 离心泵及CFD数值模拟基本理论 15

2.1 离心泵简介 15

2.1.1 离心泵的基本概述 15

2.1.2 离心泵的工作原理 16

2.1.3 离心泵的工作特性 16

2.2 离心泵效率和性能的影响因素 18

2.3 原油离心泵性能曲线换算方法 19

2.3.1 离心泵性能曲线的换算因素 19

2.3.2 介质粘度对离心泵性能的影响 19

2.3.3 原油离心泵性能曲线的研究方法 19

2.3.4 离心泵性能曲线的换算 20

2.4 离心泵叶轮的切割计算 22

2.5 CFD数值模拟基本理论 25

2.5.1 计算流体力学简介 25

2.5.2 计算流体力学的控制方程 27

2.5.3 控制方程的求解方法 30

2.5.4 湍流模型 33

2.6本章小结 35

第三章 离心泵数值计算模型的建立 36

3.1 实体建模 36

3.1.1 Solidworks软件简介 36

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