分流叶片对离心压缩机性能影响的数值分析

以一种高压比离心式空气压缩机为研究对象,主要针对不同的分流叶片长度,采用商用软件ANSYS-CFX 对其叶轮内部三维流场进行数值模拟计算。计算结果表明,应用分流叶片可以不同程度提升该压缩机的整体性能,最大可提高效率2%以上。通过对比各计算结果的熵分布云图,分析了分流叶片长度对压缩机性能造成影响的原因。     

分流叶片对离心压缩机叶轮内流及性能影响的数值研究

对包含分流叶片的离心压缩机叶轮内部流场进行了全三维数值仿真,分析了分流叶片对叶轮流场与性能的影响,并与不带分流叶片的叶轮内部流场进行了比较.     

含分流叶片的离心压缩机级的数值分析

对含分流叶片的离心压缩机级进行了三维数值试验.重点分析了叶轮、扩压器和蜗壳部件中的流动特征,另外,数值计算的结果表明:离心叶轮分流叶片的位置、扩压器宽度,以及蜗壳型式等方面的不同选择都会对压缩机的性能造成一定的影响.最后对数值计算的精度进行了分析说明.     

磨削叶片对离心式通风机性能的影响

分析了离心式通风机叶片尾迹流产生的原因及其影响，介绍了叶片尾迹损失的计算方法。通过一个试验实例，说明了对叶片工作面进行磨削处理，可以减少尾迹损失，提高风机的效率，同时对降低风机的噪声也非常有利。     

分流叶片对离心泵流场和性能影响的数值预报

针对低比速离心泵IS 50-32-160模型,给出不同叶片数下、不同分流叶片长度的设计方案,采用计算流体力学(Computational fluid dynamics, CFD)方法,对多方案的全流场进行分析。对非设计流量工况计算采用了稳态N-S方程求解,对于叶轮和蜗壳、前后腔体的交界面采用滑移网格技术进行处理。通过叶轮叶片上扭矩分析,并结合以往试验和计算经验,给出适用于低比速离心泵分流叶片长度的设计公式;流场计算结果显示：分流叶片有利于叶轮出口和蜗壳入口的压力、速度分布均匀性,能有效提高叶轮出口压力,减小压力脉动;通过不同工况的计算模拟,预测各个设计方案离心泵的性能,结果表明：含分流叶片离心泵的效率向偏大流量处偏移,扬程提高较多,且功率曲线更加陡峭。最后总结了不同叶片数对水泵性能的影响,给出不同设计要求时叶片数取值参考。     

分流叶片位置对离心压缩机级内部流动和性能影响的数值研究

运用数值求解叶轮机械内部三维粘性流场的方法,对工程上常用的某带分流叶片的离心压缩机叶轮及后接有叶扩压器的内部流动和性能进行数值研究。通过求解分流叶片处于不同周向位置和其前缘处于不同流向位置时级的流场,得到了对应的内部流场和压力、效率与流量的性能曲线。结合对级性能曲线和内部流场的详细分析,结果表明:分流叶片处于不同的周向位置和其前缘处于不同流向位置时对级的内部流场和性能曲线影响很大,分流叶片中间叶高处前缘位置位于50%左右和周向位置距长叶片吸力面一侧1/10栅距左右,级性能较佳。     

离心压缩机叶轮分流叶片对性能的影响

某离心压缩机三元流叶轮由于在入口处无加工空间,因此改为带有分流叶片的叶轮。为了验证改造后的叶轮是否满足设计参数以及和原始叶轮的异同,采用了数值方法对原始叶轮和改造后的叶轮进行了数值分析。结果表明,两种均满足设计要求,并且改造后的叶轮性能要好于原始叶轮。这是由于原始叶轮在入口处的相对马赫数较大,因此所引起的摩擦损失也略大。     

提高离心式板型叶片通风机性能的途径

提高离心式板型叶片通风机性能的途径沈阳鼓风机厂吴明柱目前，在我国离心式（板型叶片）通风机在现场运行数量达千台，大多仍为六十年代、七十年代，甚到还有五十年代的，少量的是七十年代后期产品，除普遍存在着的效率低，噪声大及耐磨性差等缺点外，还反映出由于现场系...     

两种不同叶片的离心叶轮的数值模拟

基于N-S方程和雷诺平均法的RNG k-ε湍流模型,采用压强连接的隐式修正SIMPLIEC算法,对两个有相同设计工况但叶片类型不同的单级双吸离心泵进行了数值模拟,荻碍了叶轮内流场的速度、压力分布,捕捉到了一些重要的流动现象.并对数值计算结果进行了深入的分析研究,揭示了两种不同叶片叶轮内的流动规律,为认识两种叶片的不同的流动特征提供了参考信息.     

离心油泵的CFD数值模拟

利用数值流体动力学CFD(computational fluid dynamics)商业软件Fluent对高速离心油泵叶轮内部的定常三维湍流进行了全流道数值模拟,以研究其内部流动规律。数值计算基于Reynolds时均N-S方程,采用了标准k-ε湍流模型和SIMPLEC算法。由于计算域由转动的叶轮和固定的蜗壳组成,使用了多重参考坐标系(MRF)把旋转区域和静止区域分开。计算得到了叶片吸力面和压力面等值线图、叶轮全流道截面(z=0)压力分布云图、叶轮全流道截面(z=0)相对速度矢量图;并对叶轮小流量工况和大流量工况进行计算。根据计算的数据对泵的外特性进行预估,给出了泵的扬程流量特性曲线、功率流量特性曲线。计算结果有助于深入了解叶轮的内部流动机理,指导叶轮的水力设计。     

离心泵内流场空化特性的数值模拟研究

针对离心泵内流场特性分析困难的问题,对离心泵流场数值模拟的几何模型建立、模型网格划分和边界条件设定进行了研究,采用计算流体力学方法,获取了在敞水性能条件下离心泵的扬程-流量、效率-流量的变化关系;结合Zwart空化模型,重点对不同有效汽蚀余量时离心泵的空化流场进行了数值模拟,得到了离心泵的内部流线和空泡分布的情况,并与该离心泵机组进行了性能测试实验,最后在此基础之上进行了对比分析。研究结果表明,所采用的数值模拟方法和空化模型合理有效,此结果可为进一步开展离心泵空化监测技术研究提供借鉴。     

增加短叶片的9-26型风机流场数值模拟

风机的设计过程中,可以采用在长叶片中间安装短叶片的方法来提高风机性能.为了深入了解增加短叶片后的风机流场,应用计算流体力学软件Fluent对某9-26型高压离心风机进行了加装短叶片后的数值模拟并对结果进行分析.计算结果显示,在相同的进出口条件下,增加短叶片的风机流量可增加约5%,出口全压平均增加约10%,叶片的长短对流量的增加也有所影响.计算中所采用的是标准k-ε湍流模型与非结构化网格.模拟结果可以有效帮助人们改进风机性能.     

带有前置搅拌装置污水泵的流动特性研究

针对污水池清淤问题,在一潜水排污泵进口处设置一搅拌装置,研究带有前置搅拌装置污水泵在污水池中的流动特性。研究表明,基于CFD计算的污水泵外特性结果与试验结果基本吻合,数值模拟结果具有较好精度;对比无前置搅拌装置的潜水排污泵,发现装有搅拌装置后泵的轴功率升高,效率下降;对整个污水池系统的流场进行分析,发现污水池内出现旋涡及附壁效应,说明泵前设置搅拌装置有利于池底清淤;固相颗粒主要聚集于叶轮流道中下游及蜗壳周边壁面处,叶片工作面的进口、出口以及叶片背面中间部位磨损稍微严重,而叶片流道中间部位及靠近叶片背面出口处的磨损相对轻微。     

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.     

Influence of blade wrap angle on centrifugal pump performance by numerical and experimental study

The existing research on improving the hydraulic performance of centrifugal pumps mainly focuses on the design method and the parameter optimization. The traditional design method for centrifugal impellers relies more on experience of engineers that typically only satisfies the continuity equation of the fluid. In this study, on the basis of the direct and inverse iteration design method which simultaneously solves the continuity and motion equations of the fluid and shapes the blade geometry by controlling the wrap angle, three centrifugal pump impellers are designed by altering blade wrap angles while keeping other parameters constant. The three-dimensional flow fields in three centrifugal pumps are numerically simulated, and the simulation results illustrate that the blade with larger wrap angle has more powerful control ability on the flow pattern in impeller. The three pumps have nearly the same pressure distributions at the small flow rate, but the pressure gradient increase in the pump with the largest wrap angle is smoother than the other two pumps at the design and large flow rates. The pump head and efficiency are also influenced by the blade wrap angle. The highest head and efficiency are also observed for the largest angle. An experiment rig is designed and built to test the performance of the pump with the largest wrap angle. The test results show that the wide space of its efficiency area and the stability of its operation ensure the excellent performance of the design method and verify the numerical analysis. The analysis on influence of the blade wrap angle for centrifugal pump performance in this paper can be beneficial to the optimization design of the centrifugal pump.     

Predicting performance of radial flow type impeller of centrifugal pump using CFD

The main objective of this work is to use the computational fluid dynamics (CFD) technique in analyzing and predicting the performance of a radial flow-type impeller of centrifugal pump. The impeller analyzed is at the following design condition: flow rate of 528 m³/hr; speed of 1450 rpm; and head of 20 m or specific speed (N_s) of 3033 1/min in US-Units. The first stage involves the mesh generation and refinement on domain of the designed impeller. The second stage deals with the identification of initial and boundary conditions of the mesh-equipped module. In the final stage, various results are calculated and analyzed for factors affecting impeller performance. The results indicate that the total head rise of the impeller at the design point is approximately 19.8 m. The loss coefficient of the impeller is 0.015 when 0.6 < Q/Q_design < 1.2. Maximum hydraulic efficiency of impeller is 0.98 at Q/Q_design = 0.7. Based on the comparison of the theoretical head coefficient and static pressure rise coefficient between simulation results and experimental data, from previous work reported in the literature [Guelich, Kreiselpumpen, Springer, Berlin, 2004], it is possible to use this method to simulate the performance of a radial-flow type impeller of a centrifugal pump. This paper was recommended for publication in revised form by Associate Editor Seungbae Lee Somchai Wongwises is currently a Professor of Mechanical Engineering at King Mongkut’s University of Technology Thonburi, Bangmod, Thailand. He received his Doktor Ingenieur (Dr.Ing.) in Mechanical Engineering from the University of Hannover, Germany, in 1994. His research interests include two-phase flow, heat transfer enhancement, and thermal system design. Professor Wongwises is the head of the Fluid Mechanics, Thermal Engineering and Two-Phase Flow Research Laboratory (FUTURE). Suthep Kaewnai obtained a B. S. degree in Mechanical Engineering, 1980 from the King Monkut’s University of Technology Thonburi and M. S. degree in Mechanical Engineering, 1983 from Chulalongkorn University. He is currently an assistant professor at King Mongkut’s University of Technology Thonburi. Suthep’s research interests are in the area of pumps and small hydroturbine. Manuspong Chamaoot received a B. S. degree, 1972 and M.S. degree in Mechanical Engineering, 1979 from the King Monkut’s University of Technology Thonburi. He is currently an assistant professor at King Monkut’s University of Technology Thonburi. His research interests are in the field of mechanical vibration for rotating equipment and computational fluid dynamics.     

不同流型对轴流通风机性能影响的数值

本文采用Navier-Stokes方程和标准k-s湍流模型,对采用两种不同流型设计的低压轴流通风机进行三维稳态内流模拟,详细分析两种流型造成叶片根部安装角变化对轴流通风机性能的影响.并对采用改进型流型设计的样机采用大涡模拟和声学模型进行噪声预测分析.计算结果表明,改进型流型设计不仅能改善叶轮根部的流动,同时也有利于风机...     

高温熔盐泵中分流叶片对结构动力特性的影响

为研究分流叶片对高温熔盐泵结构动力特性的影响规律,以IS50-32-160型低比转数高温熔盐泵为研究对象。对有/无分流叶片方案不同工作温度、不同工况下的泵转子进行基于ANSYS Workbench的数值计算,分析了泵内部的应力、变形和模态分布规律。研究结果表明:添加分流叶片后,叶轮的等效应力明显减小,说明分流叶片能够有效提高叶轮的承载能力;分流叶片使得转子的变形情况也得到一定的改善,从而降低了叶轮变形对内部流场的影响,且叶轮内的变形分布变得更均匀,从而可减轻泵转子的振动;同时,不同工作温度对泵转子的固有频率及各阶振型影响均不大。