Coupled Numerical Simulation of Electromagnetic and Flow Fields in a Magnetohydrodynamic Induction Pump

Magnetohydrodynamic(MHD)induction pumps are contactless pumps able to withstand harsh environments.The rate of fluid flow through the pump directly affects the efficiency and stability of the device.To explore the influence of induction pump settings on the related delivery speed,in this study,a numerical model for coupled electromagnetic and flow field effects is introduced and used to simulate liquid metal lithium flow in the induction pump.The effects of current intensity,frequency,coil turns and coil winding size on the velocity of the working fluid are analyzed.It is shown that the first three parameters have a significant impact,while changes in the coil turns have a negligible influence.The maximum increase in working fluid velocity within the pump for the parameter combination investigated in this paper is approximately 618%.As the frequency is increased from 20 to 60 Hz,the maximum increase in the mean flow rate of the working fluid is approximately 241%.These research findings are intended to support the design and optimization of these devices.

Application and prospect of the fluid cooling system of solar arrays for probing the Sun

The Solar Close Observations and Proximity Experiments(SCOPE)mission,which has been proposed by the Yunnan Observatories,Chinese Academy of Sciences,aiming to operate at a distance of 5 to 10 solar radii from the Sun,plans to complete the in situ detection of the solar eruption process and observation of the magnetic field structure response.The solar flux received by the satellite ranges from 10^(3) to 10^(6) Wm^(-2),which poses challenges for thermal management of the solar arrays.In this work,the solar array cooling system of the Parker Solar Probe is discussed,the developments of the fluid loop technique are reviewed,and a research plan for a next-generation solar array cooling system is proposed.This paper provides a valuable reference for novel thermal control systems in spacecraft for solar observation.

Flow Ripple of Axial Piston Pump with Computational Fluid Dynamic Simulation Using Compressible Hydraulic Oil

The flow ripple, which is the source of noise in an axial piston pump, is widely studied today with the computational fluid dynamic（CFD） technology development. In the traditional CFD modeling, the fluid compressibility, which strongly influences the accuracy of the flow ripple simulation results, is often neglected. So a compressible sub-model was added with user defined function（UDF） in the CFD model to predict the flow ripple. At the same time, a test rig of flow ripple was built to study the validity of simulation. The flow ripple of pump was tested with different working parameters, including the rotation speed and the working pressure. The comparisons with experimental results show that the validity of the CFD model with compressible hydraulic oil is acceptable in analyzing the flow tipple characteristics. In this paper, the improved CFD model increases the accuracy of flow ripple rate to about one-magnitude order. Therefore, the compressible model of hydraulic oil is necessary in the flow ripple investigation of CFD simulation. The compressibility of hydraulic oil has significant effect on flow ripple, and the compression ripple takes about 88% of the total flow ripple of pump. Leakage ripple has the lowest proportion of about 4%, and geometrical ripple leakage ripple takes the remnant 8%. Besides, the influence of working parameters was investigated through the CFD simulations and experimental measurements. Comparison results show that the amplitude of flow ripple grows with the increasing of rotation speed and working pressure, and the flow ripple rate is independent of the rotation speed. However, flow ripple rate of piston pump grows with the increasing of working pressure, because the leakage ripple will increase with the pressure growing. The investigation on flow ripple of an axial piston pump using compressible hydraulic oil provides a more validity simulation model for the CFD analyzing and is beneficial to further understanding of the flow ripple characteristics in an axial piston pump.

Numerical Investigation on Fluid Structure Interaction Considering Rotor Deformation for a Centrifugal Pump

The existing research for unsteady flow field and the corresponding flow induced vibration analysis of centrifugal pump are mainly carried out respectively without considering the interaction between fluid and structure. The ignorance of fluid structure interaction （FSI） means that the energy transfer between fluid and structure is neglected. To some extent, the accuracy and reliability of unsteady flow and rotor deflection analysis should be affected by this interaction mechanism. In this paper, a combined calculation between two executables for turbulent flow and vibrating structure was established using two-way coupling method to study the effect of FSI. Pressure distributions, radial forces, rotor deflection and equivalent stress are analyzed. The results show that the FSI effect to pressure distribution in flow field is complex. The pressure distribution is affected not only around impeller outlet where different variation trends of pressure values with and without FSI appear according to different relative positions between blade and cutwater, but also in the diffusion section of volute. Variation trends of peak values of radial force amplitude calculated with and without FSI are nearly same under high flow rate and designed conditions while the peak value with FSI is slightly smaller, and differently, the peak value with FSI is larger with low flow rate. In addition, the effect of FSI on the angle of radial force is quite complex, especially under 0.5Q condition. Fluctuation of radial deflection of the rotor has obvious four periods, of which the extent is relatively small under design condition and is relatively large under off-design condition. Finally, fluctuations of equivalent stress with time are obvious under different conditions, and stress value is small. The proposed research establishes the FSI calculation method for centrifugal pump analysis, and ensures the existing affect by fluid structure interaction.

Viscous flow simulations through multi.lobe progressive cavity pumps

Computational fluid dynamics(CFD)simulations of multi-lobe progressive cavity(PC)pumps are limited in the literature due to the geometric complexity of the pump,which places numerous restrictions on the grid generation process.The present study attempts to alleviate such restrictions by developing a detailed numerical procedure for the numerical simulations of multi-lobe progressive cavity pumps.The profile equations for the multi-lobe configuration at any section at each instant of rotation are presented.A structured grid generation method is developed to generate mesh files required for CFD simulations of multi-lobe PC pumps.Results from the present procedure are validated against single-lobe PC pump numerical results available in the literature.Finally,a numerical parametric study is carried out to investigate the effect of the number of lobes,the stator pitch,the circular fillet and clearance on the volumetric efficiency of PC pumps with viscous oils.

Computational Fluid Dynamics Analysis of Shroud Design on Hemodynamic Performance and Blood Damage in a Centrifugal Blood Pump

Patients with extracorporeal membrane oxygenation still suffer from high rates of complication that linked to the flow field within the blood pump.So it is essential to optimise the geometry of the pump.The specification of shroud design is arguably the necessary design parameter in the centrifugal pump.However,the hemodynamic performances of the different shroud designs have not been studied extensively.In this study,ten different shroud designs were made and divided into two groups as the different covering locations(A:Covering the blade leading edge,B:Covering the blade trailing edge).In every group,six shroud designs with the covering proportions of 0,1/5,2/5,3/5,4/5,1 were made.Detailed computational fluid dynamics(CFD)analyses were performed to investigate their effects on hemodynamics and hydraulic performance at the constant flow condition(4000 rpm,5 L/min).The percentage volumes of the scalar shear stress in specific threshold(τ<1 Pa:Thrombosis,τ>9 Pa:the destruction of von Willebrand factor,τ>50 Pa:Platelet activation,τ>150 Pa:Break of red blood)were used to compare the blood damage of the different shroud designs.Also,the modified index of hemolysis(MIH)were calculated based on a Eulerian approach for different pumps.CFD simulations predicted an increase in the pump head,hydraulic efficiency,a fraction of fluid volume with scalar shear stress values above a threshold(9 Pa,50 Pa,150 Pa)and MIH with increasing shroud covering proportions from 0 to 1 in the same covering location.Also,these above results were higher in group B than group A.This means that the risks of the hemolysis,thrombosis and bleeding increased as the rise of the covering proportion and they were higher in the pump whose shroud covers the blade trailing edge.

Effect of Viscosity on Pumping-Up of Newtonian Fluid Driven by a Rotating Cone

Effect of viscosity on flow patterns of pumping-up of liquid generated by a cone rotating at the liquid surface has been experimentally studied with various concentrations of glycerol aqueous solution. We have previously found that the higher viscous non-Newtonian fluid was lifted-up along the conical surface with a radial filament-wise pattern, which is quite different from the monotonic thin film-wise pattern observed for the lower viscous fluid such as water. In order to elucidate the pumping-up mechanism, a transition diagram indicating the critical rotation rate is obtained as a function of viscosity?of Newtonian fluid in this study, varying from the lower value of water (μ?=?0.890 mPa·s) to the higher one of glycerin (μ?= 910?mPa·s). It is found that there are three categories depending on the viscosity classified as?1) film-wise pumping-up region for the viscosity?μ?≤?134?mPa·s,?2) filament-wise pumping-up one for the viscosity?μ?≥?520?mPa·s, and?3) no pumping-up phenomenon occurs?for 134??μ??mPa·s.

Research on two-dimensional fluid vibration axial transmission path model of axial piston pump

High speed and high pressure can enhance the vibration of axial piston pump. A fluid vibration transmission law of axial piston pump is studied in this paper. According to harmonic response analysis results, a transmission path analysis is used to establish a two-dimensional fluid vibration transmission path model in the vertical plane, which has characteristics of multi excitation sources, multi-path and multi-receptors. Model parameters are obtained by experimental and numerical analysis. Matlab is used to solve the model, and acceleration vibration response of three shells is got. To reduce the effect of mechanical vibration, the surface acceleration of pump is tested under low speed condition. Results show that the model can accurately reveal transmission law of fluid vibration and the accuracy is more than 90%. The research lays a foundation for exploring vibration transmission law and vibration control.

Analysis of fluid vibration transfer path and parameter sensitivity of swash plate axial piston pump

Taking swash plate axial piston pump as the research object,the mechanism of fluid vibration and transfer rule are analyzed.The pump shell can be assumed as the ultimate recipient of vibration transmission,the path model and differential equations from the fluid to the shell are established.The parameters of the path model are determined by the simulation software,and the mathematical model is solved by the simulation software.And time/frequency domain analysis of vibration acceleration of shell is presented.Based on the different influence of various parameters in the transfer path model on transfer characteristics and vibrational recipients,the time-varying parameters are studied by using sensitivity analysis theory,and the influence of the structural parameters on the vibration characteristics of vibration subject is quantitatively analyzed.The research in the paper provides theoretical basis for vibration analysis and structure parameter optimization of axial piston pump.

Maintaining Optimum Pump Performance with Specially-Formulated Hydraulic Fluids

This paper describes a battery of tests, and related results, that were performed under normal and severe conditions designed to demonstrate that hydraulic fluids formulated with Lubrizol’s high quality anti-wear hydraulic fluid technology can stand up to today’s increasing demands for longer life and provide excellent performance under higher operating temperatures and pressures.

Computational study of fluid-borne noise in vertical inline pump

The objective of present work is to find out the sources of fluid-borne noise in vertical inline pump for various flow rates. The three-dimensional unsteady Reynolds Average Navier Stokes equation was solved using computational fluid dynamics code to predict the acoustic distribution. The pump chosen for study was of low specific speed and the experimental performance characteristic was very well matched with computational head developed. PROUDMAN sound power contour analysis showed the critical zone of noise in inlet pipe,impeller,and volute. Based on this,the variations of acoustic power were depicted over the cross section of inlet pipe,along the mean streamline of inlet pipe,as well along the volute circumference. The result concludes that the predominant flow noise is at tongue region and followed by noise generated due to turbulence in inlet pipe which occurs by the sudden variation in flow passage as well it depends on the operating condition of pump. The frequency analysis gives a glimpse of understanding about the broadband noise distribution due to flow phenomenon over a frequency range.

主动脉穿刺型轴流血泵折边结构叶轮的数值模拟及溶血分析

为解决血泵因叶顶间隙泄漏而造成溶血和血栓等问题,引入了一种折边不等间距叶轮,采用计算流体力学(computational fluid dynamics, CFD)进行内部流场的数值模拟,并与非折边不等间距叶轮及折边等间距叶轮进行对比分析,研究了它们的内流场动力学特性和血液相容性.结果表明:折边叶片结构血泵避免了叶顶间隙泄漏流的产生,同时折边不等间距叶轮减少了叶轮入口和出口处的回流和涡流,流道内整体切应力低于其他2种叶轮;3种叶轮的溶血指数HI均满足血泵的溶血设计指标,其中,折边不等间距叶轮血泵壁面切应力在0~150 Pa的占比达96.84%,曝光时间相对集中且满足人工血泵设计要求,溶血指数较非折边不等间距叶轮血泵下降了3.50%,较折边等间距叶轮血泵下降了12.50%,溶血性能最优.提出的折边不等间距叶轮血泵可有效降低红细胞破损概率,减少溶血和血栓的发生,可为轴流血泵的结构设计和优化提供一定参考.

CAP1400核主泵叶轮动应力计算及疲劳寿命预测

为实现核主泵叶轮疲劳寿命预测,考虑叶轮高温高压的恶劣运行工况建立流-热-固耦合计算模型,应用ANSYS CFX软件对核主泵叶轮内部流动的压力载荷和温度载荷进行非定常数值计算,在ANSYS Workbench中实现载荷向结构的传递,并对叶轮动力响应疲劳载荷开展研究.利用雨流计数法对叶片危险部位的载荷数据进行统计分析,进一步结合Palmgren-Miner理论对核主泵叶轮的最小疲劳寿命周期进行预测.研究结果表明:叶轮在旋转过程中承受周期性交变应力的作用;叶轮叶片进、出口边与前、后盖板交接处容易发生内部应力集中,最大应力出现在叶片出口边与前盖板交接处,为142.57 MPa;叶片各危险部位承受应力波峰和波谷的时间基本一致;叶轮产生的疲劳为应力疲劳,疲劳破坏首先发生在叶片进口边与后盖板交接处;计算得到叶轮的疲劳寿命为277.94 a.研究结果可为叶轮的动态强度优化和疲劳设计提供一定参考.

双吸泵静腔室数值优化与试验分析

【目标】探究影响双吸离心泵效率的主要因素及关键参数,优化设计吸水室以提高水力性能。【方法】基于水力损失最小原则,对吸水室与蜗壳内部流道形状进行设计,研究过流断面面积演变规律。采用CFD数值计算方法对优化前后的泵内流特征及性能特性进行对比分析,并利用实体模型试验验证优化方案的实际性能。【结果】改良设计的工况点效率比原型设计提升3.36%;在0.7QBEP(设计工况)至1.2QBEP范围内,整泵效率相较改进前模型均有所提高。其中,蜗壳水力损失降低明显,除1.3 QBEP损失下降6.18%以外,其余工况下蜗壳水力损失降低幅度均超过20%。对于吸水室,大于0.98 QBEP流量工况时,改进后模型吸水室损失低于改进前模型。【结论】吸水室、蜗壳内部流道的优化设计,明显改善了吸水室内部的不稳定流动,消除了叶轮出口附近的流动旋涡,显著降低水力损失,有效提升双吸泵的水力效率。

螺旋缝隙泄漏双向流固耦合方法

针对螺杆泵泄漏机理,利用数值模拟加数据拟合方法,提出了一种针对螺杆泵螺旋微小缝隙泄漏的双向流固耦合模拟方法.利用此方法,对比了单向流固耦合和双向流固耦合方法在螺杆泵泄漏计算结果的偏差,计算结果表明,间隙越小偏差越大,间隙为0.500 mm时两结果相差20.3%,说明螺杆泵这种刚柔配合螺旋缝隙泄漏必须利用双向流固耦合求解才能获得准确结果.随后利用双向流固耦合方法对三维螺杆泵模型进行有限元分析求解,研究了初始间隙、流体介质黏度、螺杆泵单级腔室压差、进出口压力对螺杆泵泄漏的影响.结果显示:泄漏量随初始间隙的增大而增大,随流体介质黏度的增大而减少;进出口压力变化对螺杆泵泄漏影响很小,可以忽略;腔室间的压差造成橡胶定子变形形成间隙,间隙随着压差增大呈线性增大.最后利用双向流固耦合方法计算了不同举升压力螺杆泵的容积效率,与试验结果对比误差在±5%以内.

螺杆泵转速对油水旋流分离管流场特性的影响

旋流分离器在井下采油螺杆泵作用下会发生复杂的振动现象,对旋流分离器内部流场造成一定影响。为研究螺杆泵不同转速下旋流分离器内部流场的变化规律,以同井注采工艺中螺杆泵作用下的旋流分离管柱为研究对象,针对振动壁面旋流分离管柱结构及工作特点,基于计算流体动力学方法、计算固体力学方法以及流固耦合理论,建立流固耦合力学模型;利用流固耦合分析方法,对双螺杆泵转动条件下井下旋流分离管柱内速度场、油相分布、涡量及湍动能等流场特性进行分析。分析结果表明:随着螺杆泵转速升高,分离器内切向速度和轴向速度强度逐渐减弱,径向速度的不对称性逐渐加剧,转速的周期性变化还会造成径向速度场分布的偏移;螺杆泵不同转速下旋流分离器内部涡量分布不同,随着转速升高,溢流管以及锥段部分附近相关流场的涡旋明显增强;旋流器溢流口附近油相体积分数会随着螺杆泵转速的升高而减小;不同螺杆泵转动状态下,大颗粒油滴的分布不同。所得结果可为螺杆泵井下旋流分离同井注采系统的设计及螺杆泵的转速设定提供参考。

导叶安装角度对离心泵叶轮结构特性的影响

为提高带导叶蜗壳式离心泵的运行稳定性,研究了不同导叶安装角度对离心泵性能及叶轮结构力学响应的影响.以某带导叶蜗壳泵为研究对象,首先对其进行流场数值模拟,再通过静态和瞬态结构分析模块将水压力载荷导入叶轮结构,以实现单向流固耦合分析,研究不同导叶安装角度下叶轮变形与等效应力变化规律,最后通过模态分析研究叶轮结构的振动特性.结果表明:随着导叶安装角度减小,泵的高效区向小流量工况偏移,并且最高效率逐渐增大,最大提高2.1%;单向流固耦合分析得到的稳态结果与瞬态结果规律一致,其中叶轮最大变形量和最大等效应力值都随流量的增大而减小,在设计工况附近,都随导叶安装角度的减小而减小,最大差值为3.3%,且最大等效应力值变化的幅值较小;预应力对叶轮干模态固有频率的影响可忽略不计,与干模态对比,湿模态下的固有频率有较显著下降.

流热固耦合下间隙对三螺杆泵转子强度的影响研究

针对三螺杆泵工作中产生的流体载荷引起螺杆卡滞问题,分析三螺杆泵齿顶间隙、啮合间隙对螺杆形变的影响。以N-S方程为基础,基于k-ε湍流模型,通过流固耦合传热方法求解三螺杆泵螺杆在流场作用下的位移、应力。研究结果表明:随着齿顶间隙和齿间间隙的增大,螺杆泵内的最大压力和最大温度都逐渐降低;螺杆转子的变形主要集中在进口位置,最大变形为0.107 mm,应力主要集中在主从转子的啮合位置,最大应力为146.82 MPa,主动转子的变形和应力小于从动转子的变形和应力;转子的变形和应力随齿顶间隙、啮合间隙的增大而减小。因此,在满足螺杆泵压缩机比、温升的情况下,应尽可能增大间隙以提高螺杆转子强度。

基于CNN-LSTM的钻井泵液力端故障诊断方法研究

钻井泵液力端工作环境复杂,容易发生故障,传统故障诊断方法难以满足钻井现场需求。针对五缸式钻井泵,开展了基于深度神经网络的钻井泵液力端故障诊断研究,设计了CNN-LSTM故障诊断模型结构,研究了LSTM对故障诊断模型性能影响。结果表明,提出的CNN-LSTM模型实现了钻井泵液力端多种工况下9类故障快速准确诊断,通过引入LSTM结构,将故障诊断准确率提升了7.85%,达到了97.67%。因此提出的CNN-LSTM故障诊断模型可为钻井现场提供一种高效准确的钻井泵液力端故障诊断方法。

高速轴向柱塞泵空化机制研究与优化

为降低高速轴向柱塞的空化程度,以某型号轴向柱塞泵为例,利用Pumplinx软件搭建CFD仿真模型,探究不同转速与不同吸油口压力对泵空化程度的影响,并结合MATLAB软件对离散的仿真结果进行拟合,得到转速、吸油口压力与吸油效率的变化规律曲线。研究结果表明:当柱塞腔内气体体积达到12%以上,柱塞泵吸油效率下降甚至无法吸油;通过提高吸油口压力可以有效降低柱塞腔的空化程度,提高柱塞泵吸油效率;为了保证泵在5000~6000 r/min下能够正常吸油且有较高的吸油效率,可以使吸油口压力值介于0.25~0.30 MPa之间,此时柱塞腔空化程度和吸油效率均达到相对稳定。