低比转速复合离心叶轮设计探讨

对低比转速复合离心叶轮的设计方法进行了探讨，给出了其滑移系数、理论扬程、叶片数、叶轮外径、叶片出口宽度、叶片出口安放角及短叶片起始处直径的计算公式，并对两台带诱导轮的复合叶轮离心泵进行了试验验证，结果表明复合叶轮能够提高杨程系数、效率和改善小流量工况下的工作稳定性，是设计高性能高速诱导轮离心泵的关键之一。     

低比转速离心泵叶轮的设计

通过对叶轮内液液流动分析，提出了减小叶轮出口射流－尾流结构的措施。为减小圆摩擦损失，对时轮结构采取了适量车削前后盖板，周向修圆叶片的方法。     

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.     

极低比转速叶轮内流体的流动分析和叶轮的设计

通过分析得出影响低比转速离心泵效率的主要原因是在叶轮出口存在二次流、边界层的分离等而引起的射流一尾迹结构并提出了改进的方法。实例表明文中提出的加大叶轮出口宽度,采用较大的叶片出口安放角,较大的叶片包角和叶片的线型前部采用较小曲率半径,后部分采用较大的曲率半径等叶轮设计方法能够设计出具有较高效率和较好性能的低比转速离心泵。     

低比转速两级复合叶轮高速离心泵的研制

阐述了两级复合叶高速泵的结构设计特点和水力设计方法。理论上采用以效率为目标函数的优化水力设计方法，并采用复合叶轮和双密封结构，经水力试验和现场运行表明，该泵具有很理想的性能指标和密封可靠性。     

低比转速高速泵复合叶轮的设计理论与工业应用

从叶轮流道相对速度分布导出了低比转速高速离心泵复合叶轮的设计原理,提出了复合叶轮的设计准规,并给出了叶片数的经验计算公式。按该准则设计的三台超低比转速复合叶轮高速离心泵均取得了很好的性能指标。     

低比转速离心泵叶轮内三维流场PIV试验及数值仿真

为研究低比转速离心泵内部流场分布情况,借助于PIV试验,结合数值仿真方法对一台叶轮直径为187 mm、比转速为70的离心泵叶轮通道流场进行了测量及数值模拟计算。为对比不同湍流模型计算结果的可信度,分别采用Standard k-ε模型、RNG k-ε模型、SST k-ω模型进行计算,并将流场计算结果与PIV试验结果进行了对比。研究结果表明：在小流量工况下,叶轮通道内速度分布较不均匀,在通道后半区域靠近叶片工作面存在明显的低速区,叶片背面的中前部区域附近出现高速区;随着流量增大,叶轮通道内部速度分布渐趋均匀,水流出口角增加。三个湍流模型计算结果与试验结果吻合较好,尤其是对低速区的模拟较好。对比三个不同的湍流模型,在小流量工况及设计流量工况下,RNG k-ε模型计算结果与试验值更为接近;在大流量工况下,Standard k-ε模型计算结果与试验值吻合更好。对比离心泵整体性能表现,扬程、效率计算结果均远高于试验测量值。     

低比转速离心油泵叶轮出口直径的优化

本文考虑粘度对离心泵基本公式中滑移系数、理论扬程的影响,对低比转速离心油泵叶轮出口直径进行了优化计算。研究表明,粘度对低比转速离心油泵的叶轮出口直径和机械效率影响很大。     

反击系数在低比转速叶轮几何参数优化中的应用

低比转速叶轮为产生较高的给定扬程,叶轮直径都相对较大。叶轮圆盘摩擦损失大约正比于叶轮直径的5次方．圆盘摩擦损失成为低比转速泵内损失的主要形式,也是这类泵效率甚低的基本原因。为改善这类泵的效率指标,曾提出了一以降低叶轮直径和圆盘摩擦损失为主要目标的优化模型。针对对这一数学模型的质疑,从叶轮的反击系数这一概念入手,论证了不可能通过叶轮几何尺寸优化同时把叶轮圆盘摩擦损失和叶轮出口冲击损失降低到最小值,由于在低比转速泵中前者占优势,因而降低这类泵的圆盘摩擦损失是提高这类泵效率的主要途径,从而在理论上论证了所讨论优化模型的正确性．     

超低比转速复合式离心泵内部流动特性分析

为研究超低比转速复合式离心泵内部流动特性,以一台比转速为16、半开式复合叶轮离心泵为研究对象,应用ANSYS-Fluent19R1软件对模型泵进行三维全流场数值模拟计算,得出泵内部流场及作用在叶轮、蜗壳上的径向力分布规律。结果表明:在不同流量工况下,随着流量的增加,在隔舌附近出现较大的压力梯度;在长叶片与短叶片相间隔流道内低速区面积较大、叶轮出口处分布较多的旋涡;当流量从0.2倍增加至1.8倍额定流量时,作用在蜗壳上的径向力幅值逐渐减小,作用在叶轮上的径向力幅值先减小后增加,在1.0倍额定流量时径向力幅值达到最小,而后增大。为超低比转速复合式离心泵的设计优化提供参考。     

Numerical prediction and performance experiment in a deep-well centrifugal pump with different impeller outlet width

The existing research of the deep-well centrifugal pump mainly focuses on reduce the manufacturing cost and improve the pump performance,and how to combine above two aspects together is the most difficult and important topic.In this study,the performances of the deep-well centrifugal pump with four different impeller outlet widths are studied by the numerical,theoretical and experimental methods in this paper.Two stages deep-well centrifugal pump equipped with different impellers are simulated employing the commercial CFD software to solve the Navier-Stokes equations for three-dimensional incompressible steady flow.The sensitivity analyses of the grid size and turbulence model have been performed to improve numerical accuracy.The flow field distributions are acquired and compared under the design operating conditions,including the static pressure,turbulence kinetic energy and velocity.The prototype is manufactured and tested to certify the numerical predicted performance.The numerical results of pump performance are higher than the test results,but their change trends have an acceptable agreement with each other.The performance results indicted that the oversize impeller outlet width leads to poor pump performances and increasing shaft power.Changing the performance of deep-well centrifugal pump by alter impeller outlet width is practicable and convenient,which is worth popularizing in the engineering application.The proposed research enhances the theoretical basis of pump design to improve the performance and reduce the manufacturing cost of deep-well centrifugal pump.     

多级离心泵首级叶轮停机特性数值研究

针对多级离心泵在突然断电情况下可能出现的意外事故问题,基于滑移网格技术、用户自定义函数和SIMPLE算法,在关死点处和给定转速下降规律情况下,对一多级离心泵首级叶轮的停机过程进行了内部非定常粘性流动的数值模拟,通过数值计算获得了多级离心泵首级叶轮停机过程的外特性和内部流场演化特性,重点分析了叶轮进口、叶轮出口和反导叶出口3个位置处的瞬态物理量变化。研究结果表明,无量纲扬程系数在停机之前和停机过程前期阶段基本不变,而在停机过程末期迅速下降,叶轮停止转动时,各个物理参数并未同步趋零,总之表现出明显的瞬态行为特征;叶轮出口处的物理量参数变化受叶轮转动影响最大,其次受叶轮进口处的参数变化影响,而反导叶出口处的参数变化最小。     

低比速离心泵叶轮优化设计进展

介绍了低比速离心泵叶轮优化设计的主要方法和模型,分析其优缺点,并着重介绍了叶轮多目标优化设计、遗传算法及神经网络等新的优化技术在叶轮优化设计中的应用,指出了低比速离心泵叶轮优化设计的发展趋势。     

离心泵内磁流变液流动特性的研究

采用Mixture多相流模型和标准的κ-ε模型,使用SMPLEC算法,应用Fluent软件,对磁流变抛光循环系统用离心泵内部水基磁流变液三维流场进行数值模拟,分析不同叶片数对泵内磁流变液流场压力、速度、颗粒体积浓度分布的影响。计算结果表明：随着叶片数目的增加,叶轮出口压力呈现出先增加后减小的趋势;叶片数目对叶轮出口处磁流变液速度大小影响不明显,对叶轮流道内的速度分布及颗粒体积浓度分布影响显著。     

Investigation of CFD calculation method of a centrifugal pump with unshrouded impeller

Currently, relatively large errors are found in numerical results in some low-specific-speed centrifugal pumps with unshrouded impeller because the effect of clearances and holes are not accurately modeled. Establishing an accurate analytical model to improve performance prediction accuracy is therefore necessary. In this paper, a three-dimensional numerical simulation is conducted to predict the performance of a low-specific-speed centrifugal pump, and the modeling, numerical scheme, and turbulent selection methods are discussed. The pump performance is tested in a model pump test bench, and flow rate, head, power and efficiency of the pump are obtained. The effect of taking into consideration the back-out vane passage, clearance, and balance holes is analyzed by comparing it with experimental results, and the performance prediction methods are validated by experiments. The analysis results show that the pump performance can be accurately predicted by the improved method. Ignoring the back-out vane passage in the calculation model of unshrouded impeller is found to generate better numerical results. Further, the calculation model with the clearances and balance holes can obviously enhance the numerical accuracy. The application of disconnect interface can reduce meshing difficulty but increase the calculation error at the off-design operating point at the same time. Compared with the standard k-ε, renormalization group k-ε, and Spalart-Allmars models, the Realizable k-ε model demonstrates the fastest convergent speed and the highest precision for the unshrouded impeller flow simulation. The proposed modeling and numerical simulation methods can improve the performance prediction accuracy of the low-specific-speed centrifugal pumps, and the modeling method is especially suitable for the centrifugal pump with unshrouded impeller.     

Optimization on the impeller of a low-specific-speed centrifugal pump for hydraulic performance improvement

In order to widen the high-efficiency operating range of a low-specific-speed centrifugal pump, an optimization process for considering efficiencies under 1.0Q_d and 1.4Q_d is proposed. Three parameters, namely, the blade outlet width b_2, blade outlet angle β_2, and blade wrap angle φ, are selected as design variables. Impellers are generated using the optimal Latin hypercube sampling method. The pump efficiencies are calculated using the software CFX 14.5 at two operating points selected as objectives. Surrogate models are also constructed to analyze the relationship between the objectives and the design variables. Finally, the particle swarm optimization algorithm is applied to calculate the surrogate model to determine the best combination of the impeller parameters. The results show that the performance curve predicted by numerical simulation has a good agreement with the experimental results. Compared with the efficiencies of the original impeller, the hydraulic efficiencies of the optimized impeller are increased by 4.18% and 0.62% under 1.0Q_d and 1.4Q_d, respectively. The comparison of inner flow between the original pump and optimized one illustrates the improvement of performance. The optimization process can provide a useful reference on performance improvement of other pumps, even on reduction of pressure fluctuations.     

低比转速离心泵叶轮的设计

通过对叶轮内液流流动分析 ,提出了减小叶轮出口射流——尾流结构的措施。为减小圆盘摩擦损失 ,对叶轮结构采取了适量车削前后盖板、周向修圆叶片的方法。     

极大流量工况下离心泵内部流场数值分析

针对离心泵极大流量工况下内部流动特性的问题,应用流体动力学软件Fluent,采用RNGκ-ε湍流模型与SIMPLEC算法,对某一高比转速离心泵内部流场进行了数值模拟,并与实验结果进行了比较。对比分析了4种不同流量工况下离心泵内部流体速度和压力分布以及离心泵的外特性。研究结果表明,在设计流量工况下,离心泵内部压力分布均匀,速度迹线平滑;较大流量工况下,蜗壳压力不断减小,速度分布不均匀;极大流量(1.7Qopt)工况下,蜗壳出口处出现局部负压现象,速度流线产生的漩涡增大,在扩散管局部位置流体受到冲击,容易出现回流现象。针对离心泵在不同工况下以及达到极大流量工况下内部流动随流量变化规律的研究,可为高比转速离心泵多工况优化设计、延长使用寿命提供参考。