混合粒径固体颗粒对滑套球座冲蚀磨损的影响

随着超长水平井施工排量和加砂量的不断增加,滑套球座冲蚀磨损日益严重。目前对液固两相流冲蚀磨损的研究较多,但均未考虑混合粒径固体颗粒对冲蚀磨损的影响。研究不同粒径混合的支撑剂对球座的冲蚀磨损,基于欧拉双流体理论,运用Fluent软件对混合粒径固体颗粒对滑套球座的冲蚀磨损进行数值模拟。结果表明：混合粒径固体颗粒与单一粒径固体颗粒对球座冲蚀磨损规律有所不同,单一粒径固体颗粒对球座冲蚀磨损速率随着粒径的增大而减小;混合粒径固体颗粒对球座冲蚀磨损速率不仅和支撑剂粒径有关,而且和不同粒径固体颗粒的比例有关,即冲蚀磨损速率随混合固体颗粒中小粒径固体颗粒比例的增大而表现出先减小后增大的趋势。模拟结果为水平井分段压裂材料的选择提供了依据。     

三层式套管滑套设计及其冲蚀规律分析

常规两层式套管滑套在投标或下管柱时存在较大的误操作风险,为此设计了1种新型3层式套管滑套,通过调研发现滑套冲蚀是影响滑套密封失效的重要原因,因此对新型3层式套管滑套冲蚀规律及工作寿命的研究具有重要意义。根据四川某页岩气井的实际压裂参数,通过冲蚀磨损仿真分析了3层式套管滑套在不同工况参数下的冲蚀规律,发现滑套喷砂口右端壁面最容易被冲蚀破坏,从而导致3层式套管滑套密封失效;通过量化计算得出了3层式套管滑套喷砂口的理论工作寿命,并通过冲蚀试验验证了该滑套喷砂口安全距离的设计满足使用要求,同时得出试验结果与仿真结果相差5.5%,验证了仿真分析的正确性。通过仿真分析与量化计算可为3层式套管滑套的密封可靠性设计提供理论依据。     

分段压裂可降解涂层球座密封设计

针对分段压裂可降解球座在井下环境中易自行降解使密封时间较短的问题,基于发明问题解决理论(TRIZ)技术冲突解决原理提出一种涂层球座锥面的创新设想,采用热喷涂工艺在可降解球座锥面制备耐降解金属涂层;应用Pro/E软件建立可降解球及球座相接触的三维几何模型,应用ANSYS软件对可降解涂层球座进行有限元仿真分析,并对可降解球座涂层锥面进行承压性能试验。仿真结果表明:可降解球的接触应力集中区域主要位于球座接触密封的涂层锥面,在接触面上的接触应力最大,最大应力值为205 MPa,并向两侧递减。试验结果表明:可降解球与球座涂层锥面可形成良好的密封系统,并且具备50 MPa承压性能。     

气动疏水阀冲蚀工况数值模拟及结构优化

采用Eulerian-Lagrangian多相流模型对Y型气动疏水阀的内部流场进行了模拟分析。通过将模拟结果与现场运行的阀门的实际状况进行对比验证了模拟的准确性。研究发现阀门密封处液滴速度大于破坏阈值速度,此处冲蚀损伤严重。为减低阀门冲蚀损伤,提出通过阀内流体中液滴对撞来降低液滴速度方法。基于此思想,在疏水阀密封封面前加装节流套装置。发现液滴速度下降了52%,冲蚀损伤大幅下降且位置远离密封面,但质量流量下降到无节流装置的56.5%。为了提高质量流量,进而提出采用循环对流式迷宫式盘片组件作为阀芯的设计。模拟计算发现阀门液滴最大速度为78.6 m/s,仅为无盘片阀门的46%,同时的质量流量为未加盘片阀门的78.2%。采用循环对流式迷宫式盘片组件作为阀芯的疏水阀适用于冲蚀严重的工况。     

吸尘装置颗粒物冲蚀磨损特性数值分析

为探究道路除尘装备吸尘装置作业时受颗粒物冲蚀磨损特性,采用计算流体动力学(CFD)方法和离散相模型(DPM),研究气固两相流作用下颗粒对其磨损特性.结果表明:颗粒物对内隔板、管路和四周隔板均产生不同程度磨损,其中壁面最大冲蚀磨损率出现在吸尘腔左侧.气固两相流冲蚀率计算中,Genenic算法准确性较高,而Finnie算法计算的冲蚀率最大值和平均值均偏低,McLaury和Oka算法计算的冲蚀率波动幅度较大.针对冲蚀磨损最严重的吸尘管,提出增加其上下径比的改进方案.优化后,吸尘管路最大和平均冲蚀磨损率均实现降低,抗冲蚀效果实现提升.     

机械密封腔流场内粒子对密封腔壁面及波纹管冲蚀分析

为研究机械密封腔内混有固体颗粒的流体,在复杂工况下对密封腔壁面及波纹管表面冲蚀的影响,以CFD理论及方法,采用k-ε湍流模型和离散项DPM模型,对固液混合流场进行模拟分析,获得密封腔内流体中介质作用下密封腔壁面及波纹管外表面的压力场分布,分析不同工作状态下固体颗粒作用下密封腔内壁和波纹管外表面的冲蚀区域分布、固体颗粒在流场中的运动轨迹,以及机械密封工作过程中流场内固体颗粒的逃逸量、运动状态的变化。结果表明:粒子主要受颗粒阻力、浮重力、压力梯度力及波纹管和密封腔表面反作用力的影响;在旋转流场中,粒子作与旋转方向一致的螺旋方式前进;无转速时,冲蚀多发生在靠近入口处的波纹管外表面,旋转流场中,冲蚀多发生在密封腔靠后位置的壁面;随着转速增加,粒子逃逸率下降。研究结论为机械密封腔的设计布局及机械密封装置的优化提供理论依据。     

智能井井下流入控制阀结构设计及密封性能分析

流入控制阀是智能井技术的核心,在油气井高温高压等复杂的环境中,流入控制阀的密封效果直接影响阀的正常工作。依据智能完井工况,设计流入控制阀的结构及其金属密封结构。利用有限元分析软件ANSYS建立金属密封结构的有限元模型,分析最大过盈量、密封圈接触面的锥度、密封圈内部槽的几何尺寸、井下压力状态等敏感性参数对密封结构密封性能的影响。结果表明,随着金属密封圈最大过盈量的增加,最大接触应力降低而最大等效应力增加,而随着接触面锥度的增大接触面长度变长,接触压力和最大等效应力均呈下降趋势;内槽锥度对金属接触对影响较小,对密封圈的等效应力影响较大,内槽锥度增大,等效应力大幅增加。综合考虑应力的影响,应选择合适的最大过盈量,密封圈接触锥度不宜太大,且应尽量减小内槽面的锥度。     

基于CFD的固井滑套冲蚀特性分析

固井滑套在分段压裂过程中,压裂液排量大,固相颗粒含量高,会导致滑套喷砂口严重破坏。文中运用稠密离散相模型(Dense Discrete Phase Model,DDPM)预测了固井滑套内部颗粒运动和分布规律,利用半经验冲蚀模型求解了颗粒对固井滑套的冲蚀率,并设计了相关试验,验证了数值模拟的正确性。结果表明,数值模拟能较准确地预测固井滑套的冲蚀位置,通过对单元冲蚀率积分可以求得质量损失,与试验结果对比相差6.5%,说明该模型能够较好地运用于高砂比下的固井滑套冲蚀模拟。在此基础上分析了固井滑套内流场、颗粒的运动分布特点,解释了冲蚀破坏的原因,有望为固井滑套的可靠性评估和进一步优化提供参考。     

含沙量和沙粒粒径对QT500材料冲蚀磨损特性的影响

利用圆盘式磨蚀试验装置模拟流体机械工况条件，对QT500和45钢进行了冲蚀磨损试验，用失重法研究了材料在不同含沙量和沙粒粒径时的冲蚀磨损特性。对试样表面微观形貌进行了观察，探讨了材料的冲蚀磨损机理和损伤规律。研究表明：随含沙量的增加，材料的磨损率也增加，但不与含沙量的增加值成正比；随沙粒粒径的增大，磨损量亦增加。QT500的冲蚀磨损机理主要是脆性剥落和疲劳破坏。     

固体杂质对输油管道弯头的冲刷腐蚀仿真研究

本文以含固体杂质的输油管道(液固两相流)为研究对象,采用COMSOL流体流动粒子追踪接口对弯头处冲蚀现象进行模拟仿真。分析不同入口流速情况下,弯头内速度分布、压力分布及冲蚀磨损率等。通过Finnie、DNV和E/CRC 3种不同的冲蚀模型分析管道弯曲部位的冲蚀速率。     

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...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

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.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

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.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.