Research on Cavitation Characteristics and Influencing Factors of Herringbone Gear Pump

Cavitation is a common issue in pumps,causing a decrease in pump head,a fall in volumetric efficiency,and an intensification of outlet flow pulsation.It is one of the main hazards that affect the regular operation of the pump.Research on pump cavitation mainly focuses on mixed flow pumps,jet pumps,external spur gear pumps,etc.However,there are few cavitation studies on external herringbone gear pumps.In addition,pumps with different working principles significantly differ in the flow and complexity of the internal flow field.Therefore,it is urgent to study the cavitation characteristics of external herringbone gear pumps.Compared with experimentalmethods,visual research and cavitation area identification are achieved through computation fluid dynamic(CFD),and changing the boundary conditions and shape of the gear rotor is easier.The simulation yields a head error of only 0.003%under different grid numbers,and the deviation between experimental and simulation results is less than 5%.The study revealed that cavitation causes flow pulsation at the outlet,and the cavitation serious area is mainly distributed in the meshing gap and meshing area.Cavitation can be inhibited by reducing the speed,increasing the inlet pressure,and changing the helix angle can be achieved.For example,when the inlet pressure is 5 bar,the maximumgas volume fraction in themeshing area is less than 50%.These results provide a reference for optimizing the design and finding the optimal design parameters to reduce or eliminate cavitation.

The Development of Gear Pump CAD/CAPP Based on Solid Works

Nowadays, many kinds of software, which have succes sf ully created the integration of CAD, CAPP and CAM, find their disadvantages in p ractical manufacturing. As a result, it is welcomed to develop small CAD/CAPP sy stems on a proper CAD platform, which aim at requirements of factories. Based on the one of the most popular three-dimensional design software SolidWorks, we successfully developed a set of gear pump CAD /CAPP software for Huaiyin Gene ral Factory of Mechanics. 1 The architecture and function of the software According to the need of the enterprises, the general structure of the software contain two subsystems, which are detailed as follows: · The gear pump CAD subsystem contains four main modules, including the optiona l design module of gear pump, module of part design, the module of entity modeli ng and the module of drawing which creates 2 D drawings of parts and assembly c orresponding 3 D modals. · The gear pump CAPP subsystem, which is a combination of creative mode and der ivate mode, also includes four modules, they are the module of access to feature s, the module of planning process route, the module of designing process sheets and the module of generating process documents. 2 The developing environment of the system Basing on Windows 98 and SolidWorks2001 platform, this system creates all functi ons by using Visual C++ 6.0 as developing tools. 3 The keys to the CAD/CAPP integration 3.1 The establishment of product information modal The information of parts is the basis of process planning. In this system, we us e feature modeling to describe the information of parts and assembly of gear pum p, and set up a fundamental basis for the whole system. The information module o f gear pump includes the information of both the assembly and the parts; the par t-describing module uses four-layer structure that is subassembly layer, part layer, feature layer and geometric layer. 3.2 The operation of the information on feature modeling After establishment of information mode of gear pump, the next key problem is ho w to transmit information of product to CAPP subsystem. In order to integrate pe rfectly, connecting CAD with CAPP directly can be a good method. In this system, all information of parts is store in the part drawing files, and the CAPP syste m can load these files to get information. The gear pumps, which are produced by Huaiyin General Factory of Mechanics, are usually belong to several similar typ es, and this means that most products possess large number of similar feature. T herefore, we can easily establish a specific feature for gear pump CAD/CAPP syst em. All parts are created by selecting these features and/or adding few special features. In the module of access to feature of CAPP subsystem, the main task is to find the features and the information will be easily got. 4 Conclusion This system successfully creates gear pump CAD/CAPP integration based on SolidWo rks. 3D CAD software provide more convenient platform for integration and will i nevitably become the mainstream of product design. By developing this system, we clearly realize the promising future of SolidWorks.

Case Study of Developing Gear Pump Design System with SolidEdge

Part and Draft modules of SolidEdge are used to construct 3D solid models and generate part drawings, while ActiveX Automation of VB is used to access engineering database files to realize dimension-driven modification of the designed parts. Moreover, VB plays the enabling role of integrating all work processes of gear pump design, resulting in a comprehensive CAD system.

Optimal rotor wear design in hypotrochoidal gear pump using genetic algorithm

The wear rate between the rotors of a hypotrochoidal gear pump is characterized.Using the knowledge of shape design on the rotors,the contact stresses without hydrodynamic effect between the rotor teeth were evaluated through the calculation of the Hertzian contact stress.Based on the above results and the sliding velocity between the rotors,a genetic algorithm (GA) was used as an optimization technique forminimizing the wear rate proportional factor (WRPF).The result shows that the wear rate or the WRPF can be reduced considerably,e.g.approximately 12.8%,throughout the optimization using GA.

Research on synchronous gear pump

Based on a comprehensive analysis of the structure and existing problems ofthe gear pump, provided a structure principle of a synchronous gear pump.The discussionsfocused on the working principle, construction features and finite element analysis ofthe hydraulic gear.The research indicates that the new pump has such advantages aslower noise, better distributed flow and a high work pressure, and it can be widely used inhydraulic systems.

Optimization of compound gear pump

This paper introduces the performances of compound gear pump. Based on the target of having the smallest mass per unit volume, the paper established a mathematical model of optimization, and obtained the results of optimization of the pump.

Application of external gear pump in water-hydraulic system

The ceramic coating technology of microarc oxidation (MAO) was utilized to modify surface properties of the movable endplate of a high pressure gear pump used in water-hydraulic system, which is made of aluminium alloy. A coMPact ceramic layer of more than 130 μm was developed on the movable endplate with the hardness up to HV1000 by means of microarc oxidation. A trial of tests conducted in a water power transmission system show that the maximum outlet pressure of the gear pump with the movable endplate treated by microarc oxidation, can reach 16 MPa. It is pointed out that the ceramic coating developed by microarc oxidation technology on the surface of aluminium alloy, is economical and feasible.

双圆弧斜齿齿轮泵转子加工刀轨规划及仿真

针对双圆弧斜齿齿轮泵转子加工方法中存在的加工效率和精度比较低等问题,提出了利用球头铣刀在数控铣床上加工双圆弧斜齿齿轮泵转子的方法。研究目标是:根据双圆弧斜齿齿轮泵转子方程,结合空间啮合原理,建立了双圆弧斜齿轮的加工坐标系,根据各坐标系之间的转换矩阵,建立了双圆弧斜齿齿轮泵转子的齿面方程,模拟使用球头铣刀进行加工过程,计算出加工刀具中心在平面和空间轨迹,同时给出判定球头铣刀不发生干涉的最大半径的方法。利用VERICUT软件建立虚拟制造环境并进行铣齿仿真加工,验证了双圆弧斜齿齿轮泵转子齿面数控加工方法的正确性及其可行性。

基于MATLAB的六极并联齿轮泵优化设计及分析

针对普通外啮合齿轮泵流量脉动品质差、质量大、成本高等问题,设计一种六极并联齿轮泵。分析六极并联齿轮泵的结构及其工作原理;对六极并联齿轮泵的瞬态流量特性进行分析,推导其单周期内的流量曲线函数;建立基于流量脉动系数、流量脉动频率和泵体体积的数学模型,选取设计变量,确定约束条件,并利用MATLAB优化工具箱中fmincon函数对目标函数进行参数优化。最后对相同理论流量和额定进出口压差下的六极并联齿轮泵及普通外啮合齿轮泵进行瞬态流量仿真和齿轮泵特性计算,并将结果进行对比分析。仿真结果表明:在结构设计合理的情况下,六极并联齿轮泵在减小流量脉动,降低振动、噪声、质量和制造成本,提高工作性能和使用寿命方面具有重要作用。

基于运动法的航空发动机高速燃油齿轮泵卸荷槽设计与验证

高压、高速、高温化使得齿轮泵固有困油问题愈发严重,传统卸荷槽结构已难以满足高性能燃油泵设计要求。为此本文提出一种基于运动法的新型卸荷槽结构设计方法,通过构建困油模型并从整泵全局角度分析齿轮参数对困油各项性能的影响规律,以确定齿轮参数并为卸荷槽设计提供约束条件;其次基于齿轮运动规律和卸荷槽设计原则进行了某型燃油齿轮泵卸荷槽的设计,并进行了多个工况下新型卸荷槽和传统卸荷槽困油特性仿真对比;最后试制了样机并通过试验验证了卸荷槽设计的有效性。研究结果表明:所设计的卸荷槽与传统矩形卸荷槽相比,同工况下最大困油压力降低63.4 MPa,流量脉动率减小33.5%,空化区域更小,工作性能更优,能够显著缓解困油带来的不利影响。采用该结构卸荷槽的齿轮泵具有高的容积效率和长时抗汽蚀能力。

基于LabVIEW和PLC的齿轮泵性能测试系统设计

对于齿轮泵的传统测试装置接线复杂、测试速度慢和不便于维护等缺点,基于S7-1200 PLC和LabVIEW软件开发平台,将测试技术与虚拟仪器技术相结合,开发了集数据采集与查询、TCP/IP通信、效率实验、生成Excel报表和数据存储等功能为一体的齿轮泵性能测试系统。从测试系统总体设计、硬件系统设计和软件系统设计3个方面进行了叙述。所开发的测试系统具有设备成本低、操作简便、易于维护和更新的优点。

泵/马达困油现象充分缓解的等排量大模数方法

为了充分缓解外啮合齿轮泵/马达困油现象,在确保产品输出能力不变的等排量前提下,分析模数对困油腔内的负荷流量、泄漏流量和卸荷流量的影响,提出了一种等排量大模数的设计方法,并基于这3种流量的瞬时平衡和同齿形参数、不同模数下卸荷面积的演绎计算,计算出困油压力并由此判断出困油现象的缓解程度。结果表明,对于给定的齿轮副和工况条件,等排量下的齿宽系数反比例于模数的3次方,模数越大,困油现象越趋于缓解,且径向力越小,但齿宽系数越小;同齿形参数、不同模数下的卸荷面积等于模数的平方乘基准模数为1下的卸荷面积,从而为同齿形参数、不同模数下的卸荷面积计算,提供了极大方便;卸荷槽外通的进出口压力互为颠倒,导致泵较马达的困油现象更严重,但等排量小模数马达同样也会出现较为严重的困油现象。得出了选择最大化/较大的模数应为泵/马达的设计准则的重要结论。

不同侧隙卸荷槽时齿轮泵理论流量的创新计算

为克服齿轮泵理论流量、排量及脉动系数计算方法的局限性与复杂性,从一个完整啮合齿面所产生的理论齿面流量入手,提出双卸荷槽间距内的理论齿面流量即为泵理论输出流量的新方法。以1.0和0.5代表侧隙的有和无,双卸荷槽对称线相对于齿轮副中心线的无量纲不对称宽度为变量,构建出理论输出流量特性的相关简洁式。结果表明:同等侧隙类型下无卸荷槽与单侧卸荷槽下的理论排量相同,有侧隙、单侧卸荷槽下的类型系数经典式确实有误;无侧隙、对称卸荷槽类型下的理论排量更大,流量脉动更小,但困油现象更严重;尤其单侧卸荷槽下的流量脉动很大和困油现象很严重,不建议采用等。本文提出的新方法原理更清晰,公式更简洁,结果更可靠,通用性更强。

基于齿廓曲线的外啮合齿轮泵排量计算

渐开线外啮合齿轮泵以结构简单、造价低廉等优点而在矿山、工程等领域应用广泛,但目前关于精准计算其瞬时流量、排量的文献较少。为此,基于齿轮啮合机制、轮齿齿廓性质以及转角和啮合点的关系,建立齿轮泵瞬时输出流量的数学及仿真模型。针对齿轮泵重合度、齿轮变位、卸荷槽、侧隙等影响因素对模型进行论证,进而提出一种精准计算渐开线外啮合齿轮泵排量的方法,并采用Simulink仿真软件对不同类型外啮合齿轮泵的瞬时流量进行仿真模拟。同时利用3种不同型号齿轮泵验证排量公式,其最大误差在5%以内。验证计算模型有效性后,基于MATLAB设计了齿轮泵计算辅助平台,实现了外啮合齿轮泵瞬时流量、排量性能可视化,以简化计算流程,适应工程化应用。

泵用微连通对称双卸荷槽及其困油与流量特性

为了充分提高外啮合齿轮泵的困油性能和完善双卸荷槽的现有设置理论,提出了一种双卸荷槽微连通对称设置的创新结构,并以常规无连通对称设置的双矩形卸荷槽为例,依次给出了创新结构的实现方法,构建了困油压力和理论流量的计算模型,比较分析了常规结构和创新结构下的困油压力、排量损失以及流量脉动质量等。结果表明:啮合点位置越接近最小困油容积位置,创新结构下的卸荷面积越大,突出解决了常规结构下该处的零卸荷面积问题;通过充分缓和常规结构下的困油压力,创新结构有效地避免了困油的高压冲击与低压气穴所造成的危害;相对于常规结构,创新结构的理论排量稍有下降,流量脉动有所加剧等。研究结果可为齿轮泵的优化设计提供参考。

麻雀搜索算法优化的外啮合齿轮泵泄漏量预测

预测齿轮泵泄漏量的变化趋势有助于定量分析其性能退化过程。变分模态分解(Variational Modal Decomposition, VMD)方法对齿轮泵原始泄漏量数据进行变分模态分解,得到本征模态函数IMF,提出一种结合麻雀优化算法(Sparrow Search Algorithm, SSA)和长短期记忆神经网络(Long-Short Term Memory, LSTM)的模型,建立VMD-SSA-LSTM模型预测齿轮泵泄漏量的变化情况,并对每一个分量进行单独预测,最后将预测结果进行叠加,获得完整的预测结果。通过对比不同时间段预测结果可知,VMD-SSA-LSTM模型较单一的LSTM模型预测结果的平均相对误差最高可减小25.2%,能够完成对泄漏量的有效预测。研究结论可为齿轮泵性能衰退的定量预测提供理论支持。

一种零泄漏的齿轮泵设计

介绍了齿轮泵的设计过程,从变位系数和压力角两个方面着手,重点阐述了依据排量和中心距设计齿轮参数的选择方法。为实现零泄露,采用了磁性联轴器代替机械密封,结构更紧凑,密封性更好。齿轮泵整体结构小巧,能满足实际需求。

IMIBSE与ISOMAP在旋转机械故障诊断中的应用

针对基本熵的区域划分标准不理想,导致无法有效测量振动信号的复杂度,使故障诊断的准确率不佳这一问题,提出了一种基于改进多尺度改进基本熵(IMIBSE)、等距特征映射(ISOMAP)和随机森林(RF)的旋转机械故障诊断方法。首先,采用基于方差的区域划分准则对基本熵进行了改进,结合改进的粗粒化处理,提出了IMIBSE,并将其用于提取故障特征;随后,利用ISOMAP对原始故障特征进行了特征降维,选择了对分类贡献最大的一组特征作为故障敏感特征;最后,基于RF建立了多故障分类器,将故障敏感特征输入至RF模型进行了训练和测试,实现了旋转机械的故障识别,利用齿轮箱和离心泵两种故障数据集将IMIBSE方法与复合多尺度基本熵、多尺度改进基本熵、多尺度基本熵进行了比较和分析。研究结果表明:IMIBSE不仅具有最佳的可视化效果,而且取得的识别准确率最高,二者均达到了100%,而二者的平均分类准确率分别为100%和99.8%;相较于其他故障诊断方法,IMIBSE方法的准确率更高,而且适用于小样本的故障识别问题。

对置端曲面齿轮柱塞泵动态特性仿真研究

为了研究对置端曲面齿轮柱塞泵参数对泵动态特性的影响,根据端曲面齿轮柱塞泵工作原理,推导柱塞运动方程。利用Adams与AMESim软件建立对置端曲面齿轮柱塞泵联合仿真模型,通过联合仿真得到不同转速与偏心率下的柱塞泵出口流量与压力的相应曲线。结果表明:转速增大,泵出口流量与压力增大,脉动幅值与脉动频率增大;偏心率增加,泵出口流量与压力增大,脉动幅值增大,脉动频率不变。

串联齿轮泵变相位角脉动特性及振动抑制试验研究

针对大流量串联泵存在的压力脉动与振动冲击问题,提出串联外啮合齿轮泵变相位角的减振降噪方法,推导出串联外啮合齿轮泵的瞬时流量及脉动不均匀系数的数学方程,理论分析串联外啮合齿轮泵不同相位角的瞬时流量脉动,分析变相位角时脉动不均匀系数的变化规律,并推导流量脉动与压力脉动的关系。针对实际相位差为0°和20°的串联泵,在串联泵出口处设置了双节流阀的负载来获得不同工况的压力脉动。推导出的压力脉动与试验值吻合,压力脉动是由一系列i次谐波组成的,频率与流量脉动相同,但振幅和相位与流量脉动不同。且试验测得20°相位角串联泵的压力脉动率比0°的降低了34.05%,20°相位角串联泵可以降低0°相位角时大部分频率下的振动幅值。串联泵变相位角可以降低流体脉动导致的振动幅值,且变相位角并未对串联泵的出口流量带来影响。