Blockage of the Deep-Sea Mining Pump Transporting Large Particles with Different Sphericity

The present study aims to plumb blockage of the deep-sea mining pump transporting large particles with different shapes. A numerical work was performed through combining the computational fluid dynamics(CFD) technique and the discrete element method(DEM). Six particle shapes with sphericity ranging from 0.67 to 1.0 were selected. A velocity triangle is built with the absolute, relative, and circumferential velocities of particles. Velocity triangles with absolute velocity angles ranging from 90° to 180° prevail in the first-stage impeller. With declining sphericity, more particles follow the velocity triangle with absolute velocity angles ranging from 0° to 90°, which weakens the ability of particles to pass through the flow passage. Furthermore, the forces acting on the particles traveling in the impeller passage are analyzed. Large particles, especially non-spherical ones, suffer from high centrifugal force and therefore move along the suction surface of the impeller blades. Non-spherical particles undergo great drag force as a result of large surface area. The distribution of drag force angles is featured by two peaks, and one vanishes due to blockage.As particle sphericity declines, both magnitude and angle of the pressure gradient force decrease. Variation of the drag force and the pressure gradient force causes clockwise deflection of the centripetal force, resulting in deflection and elongation of particle trajectory, which increases the possibility of blockage.

Fluid characteristic of multiphase fluid in annular space between pump barrel and plunger

The pump performance parameters,such as pump pressure,plunger friction and pump valve resistance,are fundamental parameters of optimal design of pump efficiency and sucker rod pumping system (SRPS).In this paper,considering the characteristic of geometrical nonlinear and rheology property of multiphase fluid,the pump performance parameters are studied.Firstly,a dynamics model of annular fluid flow is built.In the detail,a partial differential equation of annular fluid is established and a computing model of fluid pressure gradient is built.Secondly,the simulation models of plunger friction and hydraulic resistance of pump valve are built.Finally,a novel simulation method of fluid pressure in annular space is proposed with software ANSYS.In order to check up the correction of models proposed in this paper,the comparison curves of experiment and simulation results are given.Based on above model,the whole simulation model of plunger pump is simulated with Visual Basic 6.0.The results show that the fluid friction of pump plunger and instantaneous resistance of pump valve are nonlinear.The impact factors of pump performance parameters are analyzed,and their characteristic curves are given,which can help to optimize the pump motion parameters and pump structural.

Microstructure and properties of ductile iron bars for plunger pump prepared by horizontal continuous casting process

Ductile iron bars(DIBs) with a diameter of 145 mm, used for plunger pump production, were made by the horizontal continuous casting(HCC). The microstructure of the samples cut at three locations with different distances away from the surface(~20 mm from the surface, half of the radius and the center of the HCCDIBs)were investigated. The mechanical properties were measured by tensile and torsion tests. Results show that after the spheroidization of graphite, the iron matrix incorporates the nodules of Format I, Size 8 close to the surface, Format I, Size 7 at the half of the radius from the surface, and Format II, Size 6 in the centre of the bar,according to the ASTM A247 standard. The content of pearlite in the matrix changes from 55%(~20 mm from the surface) to 70%(half of the radius) and 80%(the center of the HCCDIBs). The strengths in tension are 552, 607 and 486 MPa with the elongations of 12.5%, 10.5% and 5.8% in samples cut at these three locations from the surface to the centre, respectively. The strength in torsion is equal to 558, 551 and 471 MPa at corresponding torsion angles of 418°, 384° and 144° respectively to the same distance from the bar surface. Fracture in tension is manifested via crack propagation through the interface between graphite nodules and matrix(Mode I), while in torsion the fracture is caused by the shear of graphite nodules(Mode II). It is shown that the transition between two fracture modes is also dependent on the size of graphite nodule. Typically, fracture Mode I was observed for nodules of smaller diameter(less than 22.7 μm) and fracture Mode II was seen for nodules of greater diameter(more than 24.8 μm).

Theoretical analysis of effect of solid phase on cavitation performance of deep-sea mining pump

In view of the present situation of low cavitation performance of deep-sea mining slurry pump, the effect of solid phase on the cavitation performance of deep-sea mining pump is analyzed theoretically. The relationship between gas and liquid phases are established by cavitation nucleon theory and mass energy equation as well as solid phase and liquid phase, and then we explored the relationship between gas phase and solid phase. The results show that the critical bubble radius and solid-phase concentration flow rate during the cavitation can be related to the liquid pressure. Eq.(19) show that the larger the solid particle concentration and the solid phase flow, the earlier the cavitation will occur, and pump anti-cavitation performance will decline.

Influence on the Solid−Liquid Two-Phase Flow from Cross-Section Area of Slurry Pumps for Deep-Sea Mining

To explore the mechanism of solid-liquid two-phase flow in deep-sea mining pumps,this paper investigates the influences of the impeller cross-section area on the multi-phase flow in the slurry pump.Experimental and numerical results are presented for two-phase flow in four impellers with different cross-section areas.They show that the degree of vortex strength and the passing capacity of particles increase as the cross-section area of the impeller.In addition,the correlations between the two-phase flow and cross-section area have been revealed by a mathematical model taking the force of the flow field into account.The simulation results confirm the theoretical analysis,while the experimental pump performances validate the numerical calculation.The influence of the cross-section area on two-phase flow and pump performance could provide theoretical support for the design of high-performance deep-sea mining slurry pumps.

基于预吸排油结构的柱塞泵配流盘优化

配流盘过渡区域的结构对于柱塞泵的脉动抑制以及减振降噪起着至关重要的作用。基于配流盘吸空抑制原理,对配流盘过渡区进行结构优化。首先计算为了平衡节流面积变化速率和柱塞腔运动速率所需增加的节流面积,并对配流盘过渡区结构进行优化。然后通过PumpLinx对轴向柱塞泵压力、流量脉动以及空化进行了仿真分析与验证。结果表明,优化后的配流盘过渡区结构可以有效降低压力、流量脉动,缓解空化发生。

考虑表面粗糙度与空化效应的组合密封润滑分析

为了研究表面粗糙度及空化效应对压裂泵柱塞密封副密封性能的影响,基于稳态Reynolds方程,建立了粗糙峰和空化效应影响下组合密封的弹流润滑数值模型.在数值模拟基础上,采用有限体积法求解稳态Reynolds方程,研究了密封副在表面粗糙度影响下的油膜厚度、油膜压力、油膜流速分布规律,以及不同的往复速度和滑环表面粗糙度对密封性能的影响.结果表明,外行程流体动压效应微弱,油膜在空气侧附近会出现空化现象;较高的往复速度有利于减小泄漏量及摩擦阻力;滑环表面粗糙度从0.8μm增加到1.8μm时,净泄漏量与外行程摩擦力分别升高了180.4%和11.17%.因此,在工作过程中应设置较高的往复速度和使用较低粗糙度的滑环以提高密封性能.

基于键合图理论的斜盘多柱塞泵建模与仿真

为了研究9个柱塞组合而成的斜盘式轴向柱塞泵的性能特征,应用键合图理论,通过AMESim仿真平台建立模型,研究斜盘倾角和配流盘窗口前端的减振槽对柱塞泵流量脉动的影响,分析扩展模型中斜盘所受的力矩。结果表明:柱塞泵斜盘倾角越大,输出的流量越多,流量脉动幅度越大;配流盘窗口的减振槽形状和大小越合理,流量脉动越小;用AMESim仿真平台中的接收和发射元件可以扩展模型,获得斜盘所受的力矩曲线。

水压泵柱塞密封性能实验装置的设计

为解决油水分离式柱塞泵的柱塞与缸套的密封可靠性及选型设计问题,研制了模拟水压柱塞泵实际运行工况的柱塞密封性能实验装置及其加载系统,并对实验装置进行了动平衡设计。在建立实验装置加载系统的仿真模型后,通过仿真对比确定了合理的加载方式。该实验装置的加载实验和稳定性实验表明,实验装置运行稳定可靠,且容积效率在合理范围内。

基于支撑力平衡的柱塞泵滑靴副油膜厚度动态求解方法

通过改进轴向柱塞泵的滑靴副与柱塞的结构设计以稳定建立滑靴油膜,这是轴向柱塞泵当前的研究热点之一。柱塞泵滑靴副油膜厚度的动态特性对分析柱塞泵滑靴副的支撑特性至关重要,为此,提出了一种基于支撑力平衡的柱塞泵滑靴副油膜厚度动态求解新方法。首先,对滑靴副的受力平衡机理进行了分析,并构建了柱塞泵运动学和动力学模型;然后,构建了柱塞泵整泵流场仿真模型,求解了包含滑靴底部支撑力、柱塞腔压力等在内的滑靴副支撑动态边界,并采用容积效率试验数据验证了整泵流场仿真的准确性;最后,建立了滑靴副油膜承载模型,分析了滑靴副油膜支撑特性,提出了基于插值计算理论的柱塞泵滑靴副油膜承载尺度动态求解方法,对1600 r/min与600 r/min两种典型工况的滑靴副油膜动态进行了计算。研究结果显示:大排量柱塞泵转速为1600 r/min时,柱塞惯性力导致高压侧油膜厚度进一步减薄,高压转低压过程中,柱塞腔内出现压力骤降,使滑靴副油膜无法形成,导致滑靴与斜盘发生刚性接触,在该区域内发生异常磨损;而在低转速工况(600 r/min)时,滑靴底面能够有效形成油膜,保证柱塞泵低速运行的可靠性。这表明基于支撑力平衡的柱塞泵滑靴副油膜厚度动态求解方法可以快速地对不同工况下的柱塞泵滑靴副油膜厚度进行求解。

柱塞泵滑靴磨损信号随机森林算法故障诊断

为了提高低负载下柱塞泵滑靴磨损故障状态诊断精度,提出基于随机森林算法的柱塞泵滑靴磨损故障状态识别方法。重点分析了低负载条件下各类柱塞泵滑靴故障信号的频域特征值,构建了特征数据库。验证了上述方法的适应性,并测试了柱塞泵不同程度松靴故障的诊断情况。研究结果表明:滑靴磨损后频域表现出明显的波动性,袋外错误率和决策树数量呈现反比变化规律,基本都在0.05附近,将决策树最优棵数n设定在400。以随机森林算法诊断特征数据库时,在250组样本中只发生了1组误识别情况,达到了98.75%的识别准确度。随机森林方法训练时间、训练准确度与测试准确度都比其它各算法更优。松靴故障诊断结果获得了高于99.5%的总体诊断准确度。采用随机森林方法柱塞泵磨损故障状态诊断表现出优异适应性,能够对柱塞泵各故障状态进行准确诊断。

柱塞泵配流盘卸荷槽开度对瞬态流场特征影响

空化是影响轴向柱塞泵性能的关键因素,柱塞缸体表面损坏是一种常见的失效形式,但目前成因尚不清晰。建立柱塞泵三维流场仿真模型,设计可观察单个柱塞腔与卸荷槽导通状态下流场特征的实验装置,并采用流体仿真和流场可视化测量的方法揭示了其成因。研究结果表明:射流角随卸荷槽开度的增大而增大,并伴随漩涡的产生与消失,射流中心速度大于20 m/s时漩涡产生;柱塞腔与卸荷槽由导通至完全截止的转变过程中,射流角由0°逐渐增大至60°,当射流角由0°向20°变化时,射流方向主要集中于柱塞缸体与配流盘腰型槽接触的表面处,导致柱塞缸体表面和配流盘吸油腰型槽上部产生射流破坏和气蚀破坏;当射流角由20°向60°变化时,射流方向将向配流盘腰型槽内部扩展,导致配流盘破坏区域由上部移向内部。上述研究结果有助于厘清柱塞缸体摩擦表面气蚀成因,为配流盘结构优化设计提供了约束条件,对提升柱塞泵的综合性能也有重要意义。

基于AMESim的多液缸合流式压裂泵流量脉动特性研究

传统的机械式压裂泵存在冲次高、冲程短、曲轴易于失效等问题,为此,提出了一种多液缸合流式液压驱动压裂泵,并对其产生流量脉动的机理进行了研究。首先,详细阐述了多液缸合流式压裂泵的工作原理,基于液压流体力学等理论,建立了多液缸合流式压裂泵的数学模型,并进行了理论分析;其次,采用AMESim仿真软件搭建了多液缸合流式压裂泵工作仿真模型,选择了合理的仿真参数设置,进行了变负载压力下的仿真研究;最后,对液压动力传递链中的活塞-柱塞运动特性、泵腔流量特性、输出流量和压力脉动特性进行了研究,并对仿真结果进行了分析。研究结果表明:在25 MPa工况下,多液缸合流式压裂泵的输出压力和流量脉动率分别为36.8%和20.61%,冲次只有42次/min,符合实际工况;多液缸合流式压裂泵输出流量脉动的主要原因是各组液缸的频繁换向、泵送行程和吸入行程的切换,导致活塞-柱塞做减速停止运动和加速启动运动。

五对置柱塞泵曲轴的多工况分析及优化

针对五对置柱塞泵曲轴在实际工况下存在的失效、共振问题,以五对置柱塞泵曲轴为例,采用理论分析和有限元分析的方法,对曲轴进行了仿真分析、结构优化和强度校核。首先,采用了ANSYS有限元分析法,研究了5DW150/16对置式柱塞泵曲轴多工况下的应力应变云图与模态响应云图,分析了曲轴不同工况下的危险截面和共振问题;然后,采用了支撑结构优化与响应面法优化两种优化方法,研究了支撑方式与结构参数对曲轴应力应变的影响;最后,采用了理论公式强度校核方法,对优化前后的曲轴是否满足设计要求进行了验证。研究结果表明:五拐两支撑结构曲轴的危险截面出现在曲柄销的过渡圆角处,不会出现共振现象;采用全支撑结构增强了曲轴的抗冲击能力,降低了曲轴的颤动,提高了整体载荷能力,保证了泵的平稳运行;采用响应面法优化后的曲轴,最大等效应力减小了15.8%,最大变形量减小了14.04%;优化前后的曲轴可以满足强度要求。

PC2-6型柴油机高压油泵柱塞卡死故障诊断及改进措施

船舶推进柴油机的单体式高压油泵结构复杂,零部件工艺要求高。由于高压油泵的柱塞偶件属于精密偶件,因此,固体颗粒物或水分对其的影响较大,很容易造成柱塞偶件卡死,高压油泵无法工作的故障。本文统计了某船推进柴油机高压油泵柱塞偶件卡死的故障案例,分析了高压油泵卡死的原因,并依据日常的经验提出解决方案和优化措施,对后续解决同类故障具有一定的实践参考价值。维护管理人员应当在使用操作和维护保养过程中做到“规范操作、正确使用、及时保养”,就能够大大减少高压油泵柱塞卡死这类故障的发生。

基于颗粒阻尼的柱塞泵减振研究

柱塞泵以及相关管网振动过大的问题,是困扰油田注水泵站安全生产的难题之一,极大的管道振动常常会引起管道的疲劳破裂,从而引发流体泄漏等安全事故。研究了基于颗粒阻尼的专用减振器,并基于有限元与离散元耦合分析算法,建立了颗粒阻尼技术阻尼分析模型,然后利用有限元方法,分析了增加颗粒阻尼前后的设备减振效果,并结合现场测试数据以及空间安装位置,设计了合理的阻尼减振方案,并完成了阻尼器的现场安装与调试,研究发现,增加颗粒阻尼减振后,设备的振动烈度降低57.5%以上,进出口管线降低45%以上,确保了设备的安全运行。

乳化液泵进液过程流场分析

利用Fluent流场分析软件对BRW125/31.5C型3柱塞式乳化液泵进液过程流场特性进行了分析,得到了进液阀启、闭过程中受到的压差力及其大小随柱塞速度的变化规律,可为开展乳化液泵配流过程流场特性研究提供参考。

某型全自动变截面板簧轧机液压系统故障分析与排除

对某型汽车板簧轧机液压系统原理及工作全过程进行了分析,对机器生产现场出现的两类故障现象进行阐示:①压下缸推动上轧滚压下钢板时,压力不够。观看压下缸压力表此时只有7MPa,钢板压制的尺寸不到位,导致报废;②设备刚启动后,控制压力油路表3压力较低,把控制油的回油管(L管路)堵塞,压力就升上来,影响压下缸正常工作进行阐示,对这两种故障原因进行分析,并分别给出解决方案,现场排除了故障。

基于数据驱动的柱塞泵冲击信号分离模型研究

针对多缸体柱塞泵冲击信号难以分离且机械故障判断困难的问题,提出了基于数据驱动的柱塞泵冲击信号分离模型。模型根据谱峭度最大原则对原始信号进行自适应带通滤波处理,根据二次包络谱峰值结合最优谐波能量和算法自动搜索柱塞泵的转速数据,根据转速对柱塞泵的单次循环大周期进行分割,以提取每个大周期内的各个密封阀单次冲击信号;判断每次单个冲击的起始时刻,设计周期时变滤波器组,对原始信号进行滤波处理,得到单一缸体的冲击信号,并计算相应的特征指标;采用实际柱塞泵振动数据对模型的准确性进行了验证。结果表明:对于具有明显冲击的三缸泵振动信号,采取分离模型分析出其转频为3.7566 Hz,信号周期为5.12 s,设计出6个周期时变滤波器组对原始信号进行处理,实现了每个密封阀的冲击信号的有效分离,便于后续对每个阀体进行独立监测和诊断分析。研究结果可为多源冲击信号的分离提取提供技术支持以及参考依据。

密相CO_(2)柱塞泵动态热流特性数值模拟研究

为了厘清柱塞往复运动过程中,密相CO_(2)柱塞泵内CO_(2)温度、压力的演变规律,考虑CO_(2)物性参数随温度、压力的变化,建立了密相CO_(2)柱塞泵的全周期三维热流耦合动态数值模型,分析了柱塞和阀的耦合运动特性、泵内CO_(2)温度场和压力场的演变,以及阀弹簧预紧力对阀位移、入口和出口回流的影响规律。研究结果表明:压缩过程是升温、升压过程,余隙容积内残留有高温、高压CO_(2);吸入阶段,余隙容积内的高温、高压CO_(2)膨胀,挤占理论容积;同时,余隙内的CO_(2)与吸入的CO_(2)混合,导致混合CO_(2)的温度升高、吸入CO_(2)的质量减少;随着吸入阀弹簧预紧力的增加,吸入阀的开启速度变慢、关闭速度变快,有效降低了回流量峰值;随着排出阀预紧力的增加,阀的最大开度、滞后角度、回流流量峰值均减小;但是,较大的预紧力会引起排出阀关闭时振荡。研究结果可为密相CO_(2)柱塞泵的优化设计提供建模方法与数据支撑。