共查询到20条相似文献,搜索用时 93 毫秒
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针对大型船舶装备中大功率电机冷却蒸发介质的密封问题,设计一种五级九齿大间隙磁性液体与磁性润滑脂组合旋转密封装置,该装置适用于大型船舶高横摇性、高腐蚀性的环境场合。通过耐压公式的理论推导,得到密封耐压能力随磁性液体的饱和磁化强度、磁性润滑脂的屈服应力和密封间隙内磁场梯度的增大而增大的结论。采用ANSYS对该装置间隙内的磁场分布进行有限元分析。在密封实验台上对该装置进行密封耐压实验,结果表明:在最大间隙0.7 mm时,其单级耐压能力仍能达到18 kPa,密封能力随转速的递增保持稳定。理论和实验表明,设计的该密封适合具有腐蚀性环境下的大功率电机或其他高振动装备的大间隙密封场合。 相似文献
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为了提高大间隙磁性液体密封的耐压能力,在多级磁源磁性液体密封的基础上提出一种新型的磁性液体与迷宫交替式组合密封结构并设计一种普通的具有二级磁源的磁性液体与迷宫交替式组合密封结构。试验研究0.3 mm到0.7 mm间隙下具有机油基、煤油基和酯基磁性液体的交替式组合密封耐压能力,数值模拟该交替式组合密封中密封间隙内的磁场强度,由磁性液体密封耐压理论计算出该交替式组合密封中磁性液体密封的理论耐压值,对交替式组合密封的试验结果与该交替式组合密封中磁性液体密封的理论耐压值进行比较和分析。结果表明,与多级磁源磁性液体密封相比,该交替式组合密封显示良好的密封能力;当密封间隙大于0.4 mm时,该交替式组合密封的耐压能力随着间隙的增大而减小。 相似文献
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针对垃圾焚烧工程急冷系统中高速离心泵密封问题,设计一种五极六靴二十四齿的磁性液体旋转密封装置,该装置适用于焚烧的高温烟气环境条件,使用寿命长。理论上推导考虑温度和离心力因素的磁性液体密封耐压公式,得出密封耐压力为线速度的二次函数,温度的一次函数。用Ansys有限元分析软件计算该密封结构分别在间隙0.4、0.5、0.6和0.7 mm下的磁性液体磁场分布。结果表明:密封耐压能力随着密封间隙的减小而逐渐递增,而由于漏磁的存在,递增的程度并非线性的;磁力线分布表明,在第一、六极靴和二、五极靴处漏磁较大。密封实验中得出最大间隙为0.7 mm时单级密封耐压能力达到51.7 kPa。 相似文献
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为探索往复密封的新方法,对2D25W-69、2.2~8.8压缩机活塞环进行往复密封研究.分析传统的往复密封方式和磁性液体往复密封的缺陷,提出组合往复密封结构的观点.针对2D25W-69、2.2~8.8压缩机活塞环工况条件,设计出三种磁性液体组合密封结构:三斜口填料-磁性液体组合密封结构,C形滑环-磁性液体组合密封结构和改进后的C形滑环-磁性液体组合密封结构.从理论上分析上述三种磁性液体组合密封结构的磁场分布和密封耐压能力.在试验方面,设计、安装了磁性液体往复密封试验台;在设计的往复密封试验台上,测试三种组合密封结构的密封性能.试验结果表明:改进后的C形滑环-磁性液体密封结构具有一定的实际价值. 相似文献
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由于驱动电机的功率和力矩的限制,一些动密封场合对启动力矩有着明确的要求,相较于传统的密封导致启动力矩较大,磁性液体密封在启动力矩方面有更大的优势。但是在不同的环境中,磁性液体密封的启动力矩波动较大,无法达到某些极端密封场合对耐压和力矩的双重要求,从而限制了磁性液体密封在该类密封场合的应用。以温度为切入点,就磁性液体密封的耐压能力和启动力矩进行理论和实验研究,得到温度与磁性液体密封耐压能力和启动力矩的关系。结果表明:磁性液体密封的间隙越小,耐压能力越大;温度越低,最大耐压值越大,-40℃时最大耐压值为80℃时的5倍;启动力矩随压力的增加而逐渐减小;温度越低,启动力矩越大,-40℃时的启动力矩接近20℃时的5倍,并且在低温磁液用量对密封启动力矩的有明显影响。 相似文献
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磁性润滑脂密封在运转过程中的温升对其使用寿命影响较大.针对这一问题,设计一种多级磁性润滑脂密封实验装置,通过实验研究密封介质压力、磁性润滑脂注入量、密封间隙及转速对磁性润滑脂密封温升的影响,分析不同转速下密封的功率损耗.结果表明:磁性润滑脂的径向截面形状以及剪切速率是温升的主要影响因素;在保证密封承压能力的前提下,适当减少磁性润滑脂注入量,增大密封间隙,可以减少磁性润滑脂的发热量;磁性润滑脂密封的功率损耗随转速升高而增大,且比理论计算结果大,因此在密封系统设计时应予以充分考虑. 相似文献
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Clarence W.DE SILVA 《Instrumentation》2019,(4):72-84
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... 相似文献
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INTEGRAL EQUATION METHOD'S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES 总被引:1,自引:0,他引:1
LI Cheng ZHENG Yanping 《机械工程学报(英文版)》2008,21(6):115-118
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. 相似文献
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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. 相似文献
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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... 相似文献
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分布动态载荷识别的抗噪处理 总被引:2,自引:2,他引:0
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. 相似文献
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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。 相似文献
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The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar... 相似文献
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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.... 相似文献
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J. A. Williams 《Lubrication Science》1997,3(3):267-306
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. 相似文献
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CHEN Sunyi 《机械工程学报(英文版)》2007,20(6):13-17
A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion. 相似文献