低比转速叶轮的优化设计

本文将优化理论应用于低比转速叶轮主要几何参数设计,针对其圆盘摩擦损失过大的特殊性,提出了区别于现行设计理论的参数确定方法。本方法建立的数学模型以降低叶轮外径值为追求目标,以求克服防碍改善低比转速叶轮效率的主要矛盾。     

低比转数泵叶轮优化设计模型

本文以降低泵叶轮圆盘摩擦损失及叶轮几何参数对叶轮流道和运行稳定性的影响作为提高低比转数泵效率的主要途径,得出了低比转数泵叶轮几何参数的优化设计模型、经计算和叶片绘型表明效果是显著的。     

再论低比转速叶轮的优化设计

以减少叶轮外径和减少圆盘磨擦损失作为主要追求目标，通过约束反应系数以适当减小叶轮出口流液的冲击损失，比较全面地优化了低比转速叶轮的出口几何参数，提高泵的效率。     

采用机械密封提高低比速泵效率的试验研究

为了提高低比速泵的效率,对一台8Dy-100单级流程泵进行了一系列试验。试验研究表明:影响低比速泵效率的主要因素是圆盘摩擦损失。为此,把叶轮前口环间隙密封改为机械密封,泵总效率提高1.8%;把叶轮后口环间隙密封改为机械密封,泵总效率提高2.8%。把后口环改为机械密封,除了基本上消除泄漏和消除了口环以下后轮盘摩擦损失,提高泵效率外,还能够平衡轴向力、取消轴封装置。     

低比转数离心泵叶轮的优化设计

针对低比转数泵圆盘摩擦损失和压水室内的水力损失过大的特点，在对现有部分优秀低比转数泵叶轮出口参数统计分析的基础上，提出了以叶轮出口绝对速度ｖ２为约束条件，以叶轮直径Ｄ２有极小值为目标函数，寻求最优的Ｄ２，ｂ２，β２和Ｚ的优化设计方法。     

离心泵圆盘摩擦损失浅析

简述现有文献中关于离心泵圆盘摩擦损失估算式的推导,以及通过泵能量平衡试验确定圆盘摩擦损失的方法。指出现行理论中关于圆盘摩擦损失的一些疑点,分析了叶轮出口用薄钢板封闭或圆盘转动这两种情况与泵实际运行时的差别,充分计及实际运行时叶轮出口排出的液体具有较大圆周分速度从而降低了圆盘摩擦损失,由此得出了离心泵圆盘摩擦损失的实际值小于按现行估算式的计算值,并初步讨论了这一新认识的意义。     

中低比转速离心泵叶轮多目标优化设计

中低比转速离心泵效率普遍不高，主要因素是泵的损失过大，在减小泵的损失时，容易使汽蚀余量增大，扬程曲线产生驼峰，为提高泵效率，减少汽蚀余量，消除扬程曲线驼峰，本文论述了以中低比转速泵的能量损失最小，汽蚀余量最小及消除扬程曲线驼峰为多目标函数，以叶轮主要参数为设计变量的泵叶轮优化设计方法，通过优化，获得了满足一定扬程和流量的最优参数组合。     

水泵叶轮喷涂环氧粉末工艺的试验研究

泵的应用很广,泵消耗的能量约占全国电力的20％。提高泵的效率是节约能源的一个重要措施。因此,我们对水泵叶轮采用喷涂工艺来提高泵效率的课题进行了试验研究。一、理论依据泵的效率是受多种因素影响的,除了泵内的机械损失、容积损失、水力损失外,还有旋转圆盘造成的摩擦损失比轴承和填料函中的磨擦损失要大好几倍,且圆盘磨擦力矩与盘壁的粗糙度成正比增加。由此可见,要提高泵的效率,在过流壁面粗糙度     

低比转速离心泵叶轮水力设计新方法综述

低比转速泵应用广泛,具有不可替代的重要性.低比转速泵的高扬程、小流量的外特性决定了这类泵的叶轮应有适合其自身特点的设计原理和方法,这些原理和方法与一般离心叶轮应有所区别.近年来,该领域新的发展和成果不断出现,低比转速离心泵的性能如效率、最大轴功率等得到了明显改善.广泛收集国内外近年所发表的有关低比转速离心叶轮的水力设计新方法的文献资料,对这些方法进行分析、整理与概括,发现其合理的先进要素,涉及低比转速叶轮主要几何参数的选择与计算、圆柱形叶片具有优势的投影型线的导出与几何特性分析,总结出低比转速离心叶轮近期出现的新的设计原则和方法,为企业设计人员的设计实践提供新的参考,以求提高这类泵的水力性能.     

中低比转速两相流杂质泵叶轮优化

目前两相流杂质泵效率偏低,主要原因为尚未有成熟的固液两相流泵的设计方法。为提高杂质泵的效率,本文运用优化思想,以能量损失最小为目标函数,以杂质泵叶轮进口直径、出口直径、叶片数、叶轮进口宽度、出口宽度、叶轮出口安放角为设计变量,经验公式中设计参数的变化范围为设计变量的约束条件,建立了杂质泵的优化模型,建模时,引用了经验速度系数法、速度比设计法的一些公式,以巩义市两相流泵厂的80LXZH-80-58泵为算例,通过优化,得到了该两相流杂质泵叶轮参数的最佳组合。该方法可提高杂质泵的效率,也为设计人员提供了杂质泵的另一参考设计方法。     

对转轴流泵的设计与数值分析

对转轴流泵是由2个叶轮串联在一起,以相反的方向绕同一轴心旋转的轴流泵.与常规前、后导叶式轴流泵相比,在同样设计参数条件下,对转式轴流泵具有相对体积小、运转速度低、抗空化性能好和推重比高等特点.为探究对转轴流泵的设计理论和方法,设计了一对转轴流泵的前、后置叶轮,应用Matlab软件实现参数化设计,搭建了自动分析优化平台,...     

不同形式高速离心叶轮内部流动的数值模拟

为分析叶轮结构对于叶轮内部流动的影响,对8叶片的闭式和半开式两种形式低比转速高速离心复合叶轮进行研究.采用S-A湍流模型和雷诺时均N-S方程,对叶轮内部的流动进行三维紊流数值计算和分析,并对离心泵进行试验研究.数值计算结果表明,两种形式叶轮内部都存在回流,其中半开式叶轮内部的回流区域较少,液流在间隙里的相对流动大致为圆周方向;叶轮内部的静压力都是由叶片进口到出口逐渐升高,等静压曲线几乎是沿圆周方向,半开式叶轮叶片顶部的静压力低于相应位置根部的静压力,闭式叶轮出口的压力系数高于半开式叶轮.试验结果表明,半开式叶轮离心泵的效率较高,说明叶轮内部的回流是影响离心泵性能的重要因素.     

Particle image velocimetry in a centrifugal pump: Details of the fluid flow at different operation conditions

Centrifugal pumps are present in the daily life of human beings. They are essential to several industrial processes that transport single- and multi-phase flows with the presence of water, gases, and emulsions, for example. When pumping low-viscous liquids, the flow behavior in impellers and diffusers may affect the centrifugal pump performance. For these flows, complex structures promote instabilities and inefficiencies that may represent a waste of energetic and financial resources. In this context, this paper aims at characterizing single-phase water flows in one complete stage of a centrifugal pump to improve our understanding of the relationship between flow behavior and pump performance. For that, a transparent pump prototype was designed, manufactured and installed in a test facility, and experiments using particle image velocimetry (PIV) were conducted at different conditions. The acquired images were then processed to obtain instantaneous flow fields, from which the flow characteristics were determined. Our results indicate that the flow morphology depends on the rotational speed of the impeller and water flow rate: (i) the flow is uniform when the pump works at the best efficiency point (BEP), with streamlines aligned with the blades, and low vorticity and turbulence in the impeller; (ii) the velocity field becomes complex as the pump begins to operate at off-design conditions, away from BEP. In this case, velocity fluctuations and energy losses due to turbulence increase to higher numbers. Those results bring new insights into the problem, helping validate numerical simulations, propose mathematical models, and improve the design of new impellers.     

一种多目标泵的设计与分析

介绍了某项目用泵的2个需求工况点,应用欧拉扬程公式计算单叶轮设计时的叶轮外径,并计算圆盘摩擦损失预估泵效率,初步分析表明单叶轮设计不仅效率极低,而且也无法满足2个设计目标。针对比开发了一种双叶轮双出口组合的新型结构型式,介绍了其工作原理。其中主要过流部件采用模型换算法,应用面积比法计算正导叶外接的首级叶轮蜗壳的第Ⅷ断面面积。根据模型试验数据换算得到该多目标泵的外特性曲线并用现代CFD技术进行了数值仿真。发现扬程—流量曲线的模型试验数据与仿真结果曲线一致,满足2个工况点的目标需求。与模型换算数据相比,数值仿真得到的数据最高效率点向大流量方向偏移,这是由于第一级蜗壳是以正导叶为基础采用面积比法设计、过流断面大导致的。     

包角对中比转速泵流场及无过载性能的影响

以D82-19-2型中比转速离心泵为研究对象,根据无过载叶轮约束公式确定叶轮设计方案,选取四种叶轮包角（150°、170°、190°和210°）开展中比转速泵流场及无过载性能的模拟研究。与实验结果相比,模拟所得扬程、效率和功率值误差不超过9%,模拟方法可行。结果表明：当叶片包角由150°增大到210°时,叶轮进口压力提高24%,低速区面积扩大至整个叶轮流道的1/3,叶片对流体的约束能力及抗汽蚀性能增强,但叶轮出口压力降低,大包角下导叶的湍流损失加剧了动能损耗;功率备用系数由1.145减小至1.025,且功率曲线出现极大值,泵的无过载特性更显著,但扬程和效率分别下降了15.4%和4.48%。研究结果为中比转速离心泵的无过载设计提供了理论依据。     

Effects of meridional flow passage shape on hydraulic performance of mixed-flow pump impellers

During the process of designing the mixed-flow pump impeller, the meridional flow passage shape directly affects the obtained meridional flow field, which then has an influence on the three-dimensional impeller shape. However, the meridional flow passage shape is too complicated to be described by a simple formula for now. Therefore, reasonable parameter selection for the meridional flow passage is essential to the investigation. In order to explore the effects of the meridional flow passage shape on the impeller design and the hydraulic performance of the mixed-flow pump, the hub and shroud radius ratio (HSRR) of impeller and the outlet diffusion angle (ODA) of outlet zone are selected as the meridional flow passage parameters. 25 mixed-flow pump impellers, with specific speed of 496 under the design condition, are designed with various parameter combinations. Among these impellers, one with HSRR of 1.94 and ODA of 90° is selected to carry out the model test and the obtained experimental results are used to verify accuracies of the head and the hydraulic efficiency predicted by numerical simulation. Based on SIMPLE algorithm and standard k-ε two-equation turbulence model, the three-dimensional steady incompressible Reynolds averaged Navier-Stokes equations are solved and the effects of different parameters on hydraulic performance of mixed-flow pump impellers are analyzed. The analysis results demonstrate that there are optimal values of HSRR and ODA available, so the hydraulic performance and the internal flow of mixed-flow pumps can be improved by selecting appropriate values for the meridional flow passage parameters. The research on these two parameters, HSRR and ODA, has further illustrated influences of the meridional flow passage shape on the hydraulic performance of the mixed-flow pump, and is beneficial to improving the design of the mixed-flow pump impeller.     

Effects of Blade Number on Characteristics of Centrifugal Pumps

The blade number of impeller is an important design parameter of pumps,which affects the characteristics of pump heavily.At present,the investigation focuses mostly on the performance characteristics of axis flow pumps,the influence of blade number on inner flow filed and characteristics of centrifugal pump has not been understood completely.Therefore,the methods of numerical simulation and experimental verification are used to investigate the effects of blade number on flow field and characteristics of a centrifugal pump.The model pump has a design specific speed of 92.7 and an impeller with 5 blades.The blade number is varied to 4,6,7 with the casing and other geometric parameters keep constant.The inner flow fields and characteristics of the centrifugal pumps with different blade number are simulated and predicted in non-cavitation and cavitation conditions by using commercial code FLUENT.The impellers with different blade number are made by using rapid prototyping,and their characteristics are tested in an open loop.The comparison between prediction values and experimental results indicates that the prediction results are satisfied.The maximum discrepancy of prediction results for head,efficiency and required net positive suction head are 4.83%,3.9% and 0.36 m,respectively.The flow analysis displays that blade number change has an important effect on the area of low pressure region behind the blade inlet and jet-wake structure in impellers.With the increase of blade number,the head of the model pumps increases too,the variable regulation of efficiency and cavitation characteristics are complicated,but there are optimum values of blade number for each one.The research results are helpful for hydraulic design of centrifugal pump.     

Design optimization of mixed-flow pump impellers with various shaft diameters at the same specific speed

In this study, the hydraulic performance of a mixed-flow pump depending on the impeller hub ratio was analyzed using Computational- fluid-dynamics (CFD). The impeller inlet shape varies according to the hub ratio even at the same specific speed. It is important to ensure an optimum impeller design according to the hub ratio in order for the impeller shape to provide the desired performance at constant specific speed. The design variables of inlet part for meridional plane and vane plane development were defined for optimum impeller design. The objective functions were defined as the total head and total efficiency of the mixed-flow pump impellers. The optimum impeller design was carried out by controlling the design variables of impeller inlet parts by using the Response-surface-method (RSM). The tendency of impeller design variables depending on the hub ratio was identified by analyzing the optimum impeller design. Further, the impeller shape was designed on the basis of the tendency of the design variables depending on the hub ratio. Finally, the performance of an impeller with the designed shape was verified by numerical analysis.     

串列式双级轴流泵性能的数值模拟

为了揭示串列泵的内部流动机理及其能量特性,采用两个具有试验结果的轴流式叶轮和一新设计的导叶串联组成了一串列式轴流泵模型。应用Pro-E对该串列泵进行三维实体造型,用数值模拟的方法计算泵内的流场。数值计算采用NUMECA商业软件。在不同的工况条件下获得前后叶轮内部的速度矢量分布。基于流场计算结果,预测包括扬程、效率和轴功率在内的串列泵性能。将数值计算的结果与原叶轮的试验结果进行对比并与首级叶轮比较,串列轴流泵次级叶轮压力面和吸力面的速度具有较大的差值。与一般的轴流泵比较,串列式轴流泵具有比较宽的高效区,最优工况点向大流量区域偏移,其轴功率不再像普通轴流泵那样随流量的增加而减小。为了分析前后叶轮的相互作用,预测不同的后叶轮叶片偏转角条件下的串列泵性能,结果表明后叶轮的叶片偏转角对串列泵性能有重大的影响。