双向压缩式新型封隔器密封性能研究

针对常规封隔器存在的接触应力分布不均匀、胶筒密封不实等问题,提出一种双向压缩式封隔器。该封隔器采用组合结构胶筒的形式,并采用在胶筒两侧同时对向均匀压缩的新型加载方式。采用ANSYS软件建立双向压缩封隔器胶筒有限元模型,研究分析该新型封隔器的密封性能,并与常规封隔器进行比较。结果表明:双向压缩式封隔器胶筒平均接触应力明显高于常规胶筒(高20%左右),接触区域更大,接触区域上的接触应力分布更均匀,胶筒的变形稳定,密封性能更好。     

梯形隔环和槽形胶筒组合式封隔器密封结构的优化设计

为了提高封隔器的密封性能,设计一种沿径向对称的梯形隔环和槽形胶筒组构成的新型密封结构,运用有限元分析方法模拟封隔器的工作状况,分析梯形隔环结构特性参数对封隔器密封性能影响,获得不同梯形隔环结构参数下封隔器胶筒组与套管壁间接触应力分布规律,并对新型密封结构进行优化。结果表明:新型密封结构选择梯形隔环中心线距离隔环端面距离10 mm、梯形隔环下底高9 mm、梯形隔环上底高8 mm,梯形隔环高度9 mm的特性参数时,其最大接触应力比常规密封结构提高了约84%。新型密封结构的胶筒组与套管壁的接触应力比常规封隔器有显著提高,提高封隔器的密封性能。     

温度变化对压裂用封隔器胶筒密封性能的影响

利用ABAQUS分析软件建立封隔器胶筒的有限元模型,分析相同工作载荷及不同工作温度下,胶筒与套管间接触应力及其沿轴向的分布规律;分析升温和降温2种情况下温度对胶筒密封性能的影响,以及考虑胶筒发生扭转时温度对密封性能的影响。结果表明:轴向载荷不变时,随着温度的升高,胶筒的密封性能也随之提高;升温时,除起始温度低于0℃以外,其各温度下升温的温差幅度越大,胶筒的最大接触应力增加幅度越大,胶筒的密封效果越好;降温时,降温的温差幅度越大,胶筒的最大接触应力减小的幅度越大,胶筒的密封性能越差;小角度扭转载荷下,作业温度的升高将提高胶筒的密封性能,但会降低胶筒密封的稳定性。     

悬挂式封隔器密封胶筒的密封性能研究

根据悬挂式封隔器密封胶筒的结构和工作特点,分析封隔器在初封和工作阶段胶筒的密封原理及其相应的自由变形、约束变形和稳定变形3种状况下的密封特性。建立胶筒密封性能分析的理论模型,应用压力法分析胶筒在约束变形和稳定变形阶段的材料、几何和应力变化等非线性关系,得出密封面接触应力分布的计算模型,并确立应用封隔器胶筒密封面接触应力判断胶筒密封性能的判别准则。建立悬挂式封隔器胶筒密封的有限元模型,有限元仿真与数值计算得到的密封面接触压力的大小和分布形状具有较好的一致性,证明了建立的理论模型的有效性。     

压裂用封隔器双胶筒组合结构的密封性能研究

利用有限元分析软件建立了封隔器双胶筒模型,分析了在58.15 MPa工作载荷下,不同环境温度对双胶筒与套管之间接触应力的影响规律。考虑压裂封隔器的高温工作环境,分析了在100℃作业温度时,上、下胶筒不同筒高对双胶筒密封性能的影响。研究结果表明,轴向载荷不变时,随温度的升高,双胶筒的密封性能也随之提高,并在100℃时上、下胶筒与套管间密封性能达到最佳,施加载荷端胶筒承担主要的密封作用。当上、下胶筒筒高相等且高度为70 mm时,上胶筒与套管间的接触应力达到最大值66.72 MPa,且上、下胶筒沿轴向的接触应力分布均较平坦,此时双胶筒的密封效果最好。上、下胶筒筒高不等时,相较于上胶筒筒高大于下胶筒筒高的情况,上胶筒筒高小于下胶筒筒高时,上、下胶筒的接触应力沿轴向均呈现较平缓的变化趋势且整体密封性能高。当上、下胶筒筒高分别为40 mm和100 mm时,双胶筒的密封效果最好。     

深水测试密闭环空压力变化下的封隔器胶筒性能分析

为探讨深水测试双封隔器由密闭环空压力变化引起的变形与强度问题,建立双封隔器胶筒结构的力学分析模型。根据工作过程中封隔器间密闭环空压力的变化,对胶筒的密封性能进行分析,得到各胶筒的应变量、等效应力以及接触应力的变化情况。分析采用胶筒不同圆形倒角参数时封隔器胶筒与套管的接触特性,研究胶筒倒角参数对封隔器密封性能的影响,得出封隔器的优化结构参数。结果显示：各胶筒的应变量、等效应力以及接触应力均随密闭环空压力的增大而增大,其中下胶筒的增大幅度最明显;各胶筒变形量随着胶筒倒角的增大无明显变化,但等效应力随着胶筒倒角的增大均减小,而随着胶筒倒角的增大上胶筒和中胶筒的接触应力均增大,下胶筒的接触应力先增大后减小。因此,一定程度上增大胶筒倒角有利于提升封隔器的密封性能,倒角半径为0.75 mm时为最优结构。     

压缩式裸眼封隔器胶筒密封结构研究

水平井裸眼分段压裂完井技术的核心工具之一是压缩式裸眼封隔器,由于封隔器处于高温、高压、复杂深部地层环境,常出现坐封压力低、坐封提前失效,主要原因是封隔器的密封结构不合理,胶筒与井壁间的接触应力低。基于弹性力学理论,推导出封隔器胶筒坐封时受到的最大接触压力,并提出了一种新型压缩式裸眼封隔器四胶筒组合的密封结构,利用Abaqus对比分析了常规和新型组合胶筒在相同条件下的接触应力分布规律,并对新型组合胶筒的端面斜角进行了优选,研究了摩擦因数对新型组合各胶筒接触应力的影响。分析表明,新型四胶筒组合封隔器能更加有效的将坐封压力传递给密封胶筒,使胶筒的接触应力显著提高且分布均匀,保证了胶筒密封的可靠性。     

压裂酸化封隔器胶筒结构密封性能分析与优化

封隔器是压裂酸化过程中的重要工具之一,而胶筒是封隔器的核心零部件,胶筒的好坏直接决定了封隔器的工作性能。针对压裂酸化用某Y344型封隔器利用有限元技术开展密封结构性能分析与优化研究,获得了胶筒对套管的接触压力分布规律,考虑接触压力与面积两个因素建立了结构密封性能评价方法,分析了胶筒长度与组数变化对密封性能的影响,为封隔器产品开发与使用提供了理论基础。     

低渗油藏水平井分段压裂封隔器密封结构研究

低渗油藏水平井分段压裂压缩式封隔器,由于处于高温、高压、复杂深部地层环境,胶筒组常出现坐封力低和坐封提前失效、胶筒与中心管间产生渗漏等问题,导致封隔器密封失效。提出一种十字锥形隔环与槽形胶筒组组合的新密封结构,基于ABAQUS软件分析其胶筒组沿井壁、中心管轴向接触应力,沿井壁的Mises应力分布,以及硬度、坐封力对其接触应力的影响。研究表明,新型密封结构的胶筒组与井壁、中心管接触更加充分,各胶筒接触应力显著提高且分布均匀,保证了封隔器的密封可靠性;胶筒组与井壁间的Mises应力降低,避免了胶筒组被撕裂;随着硬度、坐封力的增加,胶筒组与井壁间的接触应力增加。     

压缩式胶筒结构优化及裸眼密封性能分析

压缩式封隔器广泛用于油田分层开采工艺，其胶筒的坐封通过高压流体作用在活塞上压缩胶筒或管柱来实现。现场作业发现：压缩式胶筒离载荷端较远，且大多采用单向加载，导致坐封不完全，接触应力与密封性能系数较低。针对上述问题，基于Mooney-Rivlin超弹模型、胶管变形及接触非线性理论，建立压缩式胶筒组有限元计算模型,从内衬套和防肩突结构开展单因素分析，并对其裸眼密封性能进行研究，结果表明：三角形内衬套能有效提高胶筒中部接触应力；金属圆环防突结构能提高胶筒密封性能系数；与常规压缩式封隔器相比，优化后的压缩式封隔器密封性能显著提高；裸眼井壁的不规则程度在一定范围内时，对封隔器的密封性能影响不大。     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

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.