船用离心泵减振降噪分析

船用离心泵在实际运行过程中出现较大的振动噪声,为控制其振动噪声的指标,本文从离心泵产生振动噪声的因素出发,对某型船用离心泵进行了设计、制造改进,将泵体由单壳体改为双壳体,泵联接方式由刚性联接改为弹性联接,通过轴承的布置方式使泵轴向推力由电机承担改为泵体本身承担,对泵体脚板加强设计,泵支座及泵底板由焊接件改为铸造件,对泵的制造工艺进行改进。经对改进后泵体进行流场分析,底板进行模态分析,并对泵运行时的振动噪声进行测试。试验结果表明,改进后的泵其振动噪声指标满足要求。     

IH200型离心泵使用与保养中有关问题的讨论

针对IH200型离心泵的运转时间大部分接近或已超过使用周期,离心泵振动大,噪声大,机械密封泄漏频繁等情况,对该泵进行结构、原理分析,制订出使用与保养计划及措施保证了泵的正常运转,泵的工作性、经济性显著提高。     

泵-管路系统振动噪声特性试验研究

泵-管路系统广泛应用于船舶均衡系统中，为研究不同工况下泵-管路系统振动特性，搭建了离心泵-管路系统的振动测试平台，通过采集不同工况下泵及管路的振动数据，分析了泵激振动、管路压力、辐射噪声与泵转速的关系，以及泵转速、阀门开度对管路振动的影响。试验结果表明，泵激振动、管路压力和辐射空气噪声均随着泵转速增加而增大，对于离心泵组的泵激振动并非在额定转速工况下振动最小，与泵的运行工况密切相关；管路压力在额定转速前已经建立，在保证泵功能性前提下，可根据使用工况适当降低转速实现降低噪声目标；泵转速、阀门开度均对管路振动有较大影响。     

不同叶片冲角离心泵内流诱导振动噪声研究

基于离心泵流动诱导振动噪声的试验测试系统,测量了不同叶片进口冲角模型泵在全流量范围内的振动和噪声信号并对其进行了处理和分析。研究结果表明:叶片进口冲角存在一个最优值,使离心泵的性能最佳;模型泵内部流动诱导的振动对泵体的影响最大,随着叶片进口冲角的增加,在各流量下模型泵噪声信号的轴频和叶频能量峰值均没有明显变化规律,但当叶片进口冲角为9°时,在1750～2250Hz频段内的噪声信号消失。     

新型串并联离心泵设计与试验

对船用串并联泵进行结构设计及加工工艺的改进,通过外特性试验数据和振动特性分析,得出了新型串并联泵满足设计参数要求,振动噪声较原始结构降低3~4d B,各个监测点的振动在各个频段的变化无规律可循,监测点的噪声也有所变化,监测考核时应布置多个监测点进行综合评价。     

基于CFD的船用离心泵流体动力振动噪声源分析

某型船用离心泵在实际运行中产生较大的流体（水）振动噪声,为控制振动噪声需要分析其产生原因。本文应用CFD技术对该泵内的整体三维流动进行了数值模拟。基于CFD计算结果,深入分析了该船用泵的水动力振动噪声源,主要是泵内存在大幅压力脉动、回流等不良流动以及汽蚀,此理论分析结果得到了基于试验台架的实泵声源级水动力噪声试验结果的验证。     

一种离心泵在小流量下振动异常的分析与处理

某食品加工厂用单级悬臂离心泵在出厂型式试验时,在额定流量工况下轴承箱体表面振动出现异常,超过ISO 5199标准规定的限值而无法出厂,影响生产进度和交货期。通过观察泵整机试验运行情况,分析试验台管路布置、泵结构和共同底座特点、泵组不同部位的振动监测及噪声测量,提出了针对性解决措施,通过后续试验验证其有效性深入分析了产生振动的根本原因,从而对同类型泵的设计、合理选型及确定最佳运行范围提供参考。     

离心泵的振动分析和预防措施探讨

基于对离心泵振动分析和预防措施的研究,阐述离心泵振动超标存在的危害,分析泵轴、联轴器是造成离心泵振动的重要原因,最后为将离心泵振动情况控制在有效范围内,给出加强设计、制造与选型工作、加强安装与维护工作等预防措施。     

多级离心泵振动现象的谐响应分析

影响多级离心泵异常振动的因素众多,如管路特性对泵工作特性的影响;输油量变化对泵工作特性的影响;空化现象对泵工作性能及振动特性的影响;离心泵转子不平衡等都会造成多级离心泵产生异常振动.针对离心泵转子不平衡可能会导致多级离心泵异常振动的问题,通过SolidWorks对离心泵转子进行三维建模,并用ANSYS对模型进行了谐响应分析,根据分析结果可以判断出叶轮受损或泵轴轻微变形使离心泵转子谐响应值发生较大偏差,得出了引起多级离心泵异常振动的原因是叶轮受损或泵轴轻微变形导致转子质量分布不均所造成的.将分析结果用于实际生产指导,对原油外输站外输泵的重点部位进行了检查修复,消除了离心泵震动异常现象.     

基于声振耦合分析的离心泵故障诊断

离心泵故障诊断一般采用接触式传感器采集的振动信号作为分析依据,但由于某些泵组的结构复杂、工况特殊,有时难以采用接触式传感器采集任意位置的振动信号。故本文采用了非接触式的传声器采集故障泵组的声音信号,并与振动信号进行耦合分析,从而利用噪声信号诊断出故障位置,为离心泵故障诊断技术提供了一个新的思路与方法。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.