小流量工况下低比转速离心泵内部流场的数值分析

针对小流量工况下低比转速离心泵内部流动特性问题,通过运用计算流体力学软件FLUENT,并采用RNG k-ε湍流模型和SIMPLE算法,对离心泵内部流场进行了数值模拟。采用3种不同网格数对离心泵模型进行了网格无关性分析以验证提高数值计算的准确性。沿进水管道至其进口端设置了监测点,分析了周向速度和轴向速度,得出了不同工况下发生回流的位置,分析比较了4种流量工况下离心泵内部的流场分布。结果表明:0.7Qd工况下,进水管道和叶轮流道中的流线均比较平滑,离心泵内部流动比较稳定。0.6Qd工况下,叶轮进口和叶轮流道开始产生了漩涡。随着流量的进一步降低,叶轮进口回流强度增大,叶轮流道中的漩涡逐渐向其相邻流道中扩展,离心泵内部的流态十分紊乱。     

化工离心泵选型

主要阐述了化工离心泵的选型特点,并与普通水泵在选型上做了比较,通过卧式化工离心泵与旋涡泵选型方法在化工领域的具体应用,为化工泵设备选型提供技术支持。     

Assessing the efficiency of centrifugal pumps

A method is developed for assessing the efficiency of centrifugal pumps, by optimization of the parameters so as to ensure maximum hydraulic efficiency. Formulas for the other components of the pump??s efficiency are presented.     

Failure of mechanical seals in centrifugal pumps

This fourth paper in the troubleshooting series deals with mechanical seals. Often a seal failure is diagnosed through visual inspection of the failed seal's components; this may yield the condition that existed in the seal cavity prior to, or at the time of, failure. The events that led to this condition are usually linked to the real cause of failure, which often requires us to move beyond the vicinity of the seal itself in our search for cause of failure. The extensive nature of this topic does not allow full coverage of all aspects of diagnosis, but this first of three discussions by Stan Shiels will deal with the prime areas associated with seal failure. His next article will address some specific in more detail.     

Numerical and experimental study on flow-induced noise at blade-passing frequency in centrifugal pumps

With the increasing noise pollution, low noise optimization of centrifugal pimps has become a hot topic. However, experimental study on this problem is unacceptable for industrial applications due to unsustainable cost. A hybrid method that couples computational fluid dynamics （CFD） with computational aeroacoustic software is used to predict the flow-induced noise of pumps in order to minimize the noise of centrifugal pumps in actual projects. Under Langthjem＇s assumption that the blade surface pressure is the main flow-induced acoustic source in centrifugal pumps, the blade surface pressure pulsation is considered in terms of the acoustical sources and simulated using CFX software. The pressure pulsation and noise distribution in the near-cutoff region are examined for the blade-passing frequency （BPF） noise, and the sound pressure level （SPL） reached peaks near the cutoff that corresponded with the pressure pulsation in this region. An experiment is performed to validate this prediction. Four hydrophones are fixed to the inlet and outlet ports of the test pump to measure the flow-induced noise from the four-port model. The simulation results for the noise are analyzed and compared with the experimental results. The variation in the calculated noise with changes in the flow agreed well with the experimental results. When the flow rate was increased, the SPL first decreased and reached the minimum near the best efficient point （BEP）; it then increased when the flow rate was further increased. The numerical and experimental results confirmed that the BPF noise generated by a blade-rotating dipole roughly reflects the acoustic features of centrifugal pumps. The noise simulation method in current study has a good feasibility and suitability, which could be adopted in engineering design to predict and optimize the hydroacoustic behavior of centrifugal pumps.     

Effects of clearance flow on the characteristics of centrifugal pump under low flow rate

Journal of Mechanical Science and Technology - The Reynolds averaged Navier-Stokes equations and the shear stress transport k-w turbulence model are employed to simulate the centrifugal pump with...     

干气密封在离心泵上的应用

P-6201脱丁烷塔顶回流泵是中压加氢装置的关键设备,泵腔介质为轻烃,其中含有30%的硫化氢。硫化氢属于强烈的神经毒素,易燃、易爆,一旦大量泄漏到环境中,将带来极大的安全隐患。由于介质中硫化氢含量较高,在使用及检修拆泵时容易造成环境污染以及对操作人员造成伤害。P-6201采用的是单端接触式机械密封,使用寿命短。随着环保意识不断加强,对炼油装置的安全及可靠性要求越来越高。公司基于环保、安全、寿命等原因考虑,必须对这类高危泵进行改造。     

Investigations of groove seal wear in centrifugal oil pumps

The paper presents the results of study of the factors affecting the wear rate in groove seal components used for crude oil centrifugal pumps. A test technique is proposed for the groove seal components that forecasts their wear resistance in specified conditions.     

高压多级离心泵口环密封动力学性能研究

针对高压多级离心泵口环密封的动力学特性求解问题,提出添加出口压力恢复系数的"有限长"理论求解方法,完善了控制方程组的边界条件,并用"打靶法"对此新边界条件下的口环密封流体控制方程组进行了Matlab编程求解。同时,为使软件脱离Matlab运行环境而独立运行,采用动态链接库的方式将内核计算程序封装,并利用VB实现了界面的设计、数据传输与内核程序的调用。研究结果表明,该程序运行流畅,对口环密封动力学特性计算精度高。     

离心泵标准效率的智能计算方法

在表格Excel软件的基础上,进行软件二次开发,建立了离心泵标准效率的智能计算方法,该计算方法具有自动化程度高,误差小,省时省力等特点,对离心泵的技术发展具有一定的指导意义。     

离心泵机械密封的选择和使用

机械密封是离心泵长周期运行的核心,也是离心泵的主要易损件之一,从机械密封材质,结构形式,使用维护等方面介绍了其使用过程中遵循的基本原则。     

Analysis of inner flow in low specific speed centrifugal pump based on LES

To investigate unsteady flow in the low specific speed centrifugal pump, a three-dimensional model of a pump that n _s is equal to 50 is modeled with the software Pro/E. With standard k-?, SST k-ω and RNG k-? turbulence model, the testing performance of pump is compared with the simulated results. Based on the result of steady flow, the unsteady flow of RNG k-? turbulence model and large eddy simulation (LES) are calculated at both design and off-design conditions. The time domain of pressure fluctuation value of indicator points, which are located interfaces between volute and impeller, has been investigated numerically. The unsteady flow characteristic of pump with RNG k-? turbulence model is compared with LES. The distribution of vortex in the volute is discovered. The results show that in steady flow, an error of 2.6% of RNG k-? is the lowest, SST k-ω of 3.65% is second and the worst is standard k-? of 4.78% at design condition. The calculated precision using RNG k-? model is highest in steady condition. Because of the interaction of relative movement between volute and impeller, the pressure fluctuation can clearly be observed. The flow separation of the blade pressure surface and the stall channels in off-designed condition is the reason that the efficiency of pump operating under off-design condition is low. The vortex intensity is obviously different in the eight sections of the volute and is gradually increasing from first section to eighth section. Large eddy simulation can discover the unsteady flow of the centrifugal pump effectively.     

Antifrictional carbon-plastic slip bearings for centrifugal pumps in power stations

Experience with FUT and FUT-B carbon-plastics in the slip bearings of oil- and gas-industry pumps is considered (oil-line pumps, extraction pumps, and pumps maintaining bed pressure). The results of laboratory and bench tests are presented. The benefits of FUT and FUT-B carbon-plastics over other antifrictional materials are outlined.     

Design principles for low-noise multistage centrifugal pumps in power plants

Basic design principles for centrifugal pumps with low vibrational activity are considered. Increase in pump vibration is due not so much to residual rotor imbalance as to design and technological factors, some of which are intrinsic to multistage pumps and cannot be eliminated by any means.     

离心泵汽蚀原因及解决方法探讨

针对兰州石化公司动力厂供水部第一循环水场泵房一台离心泵在运行过程中出现严重汽蚀的问题,从离心泵产生汽蚀的机理及流体力学方面的基本公式,分析超流量对泵汽蚀的影响并总结出引起离心泵汽蚀的常见原因及其解决方法。     

Impeller inlet geometry effect on performance improvement for centrifugal pumps

This research treats the effect of impeller inlet geometry on performance improvement for a boiler feed pump, who is a centrifugal pump having specific speed of 183 m·m³min⁻¹·min⁻¹ and close type impeller with exit diameter of 450 mm. The hydraulic performance and cavitation performance of the pump have been tested experimentally. In order to improve the pump, five impellers have been considered by extending the blade leading edge or applying much larger blade angle at impeller inlet compared with the original impeller. The 3-D turbulent flow inside those pumps has been analyzed basing on RNG k-ɛ turbulence model and VOF cavitation model. It is noted that the numerical results are fairly good compared with the experiments. Based on the experimental test and numerical simulation, the following conclusions can be drawn: (1) Impeller inlet geometry has important influence on performance improvement in the case of centrifugal pump. Favorite effects on performance improvement have been achieved by both extending the blade leading edge and applying much larger blade angle at impeller inlet; (2) It is suspected that the extended leading edge have favorite effect for improving hydraulic performance, and the much larger blade angle at impeller inlet have favorite effect for improving cavitation performance for the test pump; (3) Uniform flow upstream of impeller inlet is helpful for improving cavitation performance of the pump. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007.