Numerical Simulation of Double Diffusive Mixed Convection in a Horizontal Annulus with Finned Inner Cylinder

The present work relates to a numerical investigation of double diffusive mixed convection around a horizontal annulus with a finned inner cylinder.The solutal and thermal buoyancy forces are sustained by maintaining the inner and outer cylinders at uniform temperatures and concentrations.Buoyancy effects are also considered,with the Boussinesq approximation.The forced convection effect is induced by the outer cylinder rotating with an angular velocity(ω)in an anti-clockwise direction.The studies are made for various combinations of dimensionless numbers;buoyancy ratio number(N),Lewis number(Le),Richardson number(Ri)and Grashof number(Gr).The isotherms,isoconcentrations and streamlines as well as both average and local Nusselt and Sherwood numbers were studied.A finite volume scheme is adopted to solve the transport equations for continuity,momentum,energy and mass transfer.The results indicate that the use of fins on the inner cylinder with outer cylinder rotation,significantly improves the heat and mass transfer in the annulus.

Study and Analysis of a Landing Gear Actuating Cylinder Inner-lock

Three kinds of landing gear actuating cylinder inner-locks of an aircrafi ： block ring lock, steel ball lock, finger lock are taken as the study object based on the mechanics, geometry, materials, technology etc and some aircrafi typical inner-lock practical applications. The working principle of the three typical actuating cylinder innerlocks are expounded and the stress and workmanship requirements of the three inner-lock core components are analyzed. The advantages and disadvantages of different kinds are compared and the characteristics and applications of the three inner-locks investigated. The research and analysis results provide valuable information for the actuating cylinder inner-lock of the aircraft landing gear design.

Evaluation of Inner Soil Pressure Acting on Opened Bottom Cylindrical Structure

An opened bottom cylinder is a large-diameter cylinder placed on a rubber base or embedded in a soil foundation. The settlement of such a cylinder differs greatly from that of a closed bottom cylinder and so does the distribution of inner soil pressure over the opened bottom cylindrical structure. Through investigation of the settlement and the inner soil pressure on the opened bottom cylinder by model experiments, the interactions among the filler inside the cylinder, subsoil and cylinder are analyzed. The adjusting mechanism of friction resistance between the inner filler and the wall of the cylinder during overturning of the cylinder is discussed. Based on the experimental study, a method for calculating the inner soil pressure on the cylindrical structure under axisymmetric loading or non- axisymmetric (with lateral) loading is proposed in this paper. Meanwhile, the effective anti-overturning ratio of the opened bottom cylinder is derived.

Base Stress of the Opened Bottom Cylinder Structures

The base stress of the opened bottom cylinder structure differs greatly from that of the structure with a closed bottom. By investigating the inner soil pressure on the cylinder wall and the base stress of the cylinder base, which were obtained from the model experiments, the interactions among the filler inside the cylinder, subsoil and cylinder are analyzed. The adjusting mechanism of frictional resistance between the inner filler and the wall of the cylinder during the overturning of the cylinder is discussed. Based on the experimental study, a method for calculating the base stress of the opened bottom cylinder structure is proposed. Meanwhile, the formulas for calculating the effective anti-overturning ratio of the opened bottom cylinder are derived.

The Intrinsic Electron with Its Properties Such as Inner Structure and Self-Mass Is in Conflict with Quantum Field Theory

The quantum field theory (QFT) is one of branches of the Standard Model. According to QFT, quantum fields are the primary entities and particles are the excitations of these fields, coming in discrete lumps with no inner structures and with properties assigned by declaration. Such view is in conflict with the observed vacuum energy density, 140 orders of magnitudes less than required by the QFT. In addition, such view is challenged by Aphysical Quantum Mechanics (AQM), a deeper quantum theory. According to AQM, the fundamental understanding of quantum reality is expanded by the addition of two fundamental categories, aphysical and elementary consciousness of elementary particles. Based on AQM and as an example, the total ontology of the intrinsic (fundamental) electron is presented with its inner structure of perfect geometry consisting of the physical charged c-ring and aphysical cylinder, and with its properties such as self-mass, spin, magneto-electrostatic field configuration and magnetic moment. The position parameter in the inner structure demonstrates that there are no two identical intrinsic electrons in the Universe thus placing a question mark over the QFT principle of indistinguishability.

一起带有程序误判的液压系统故障分析

某热轧板生产线卸卷车的升降由液压缸驱动,升降高度的检测采用了间接测量方法,通过流量计先测量进出油缸无杆腔的油量,再由PLC进行计算得到位置数据。相对于常规采用的位移传感器直接测量方法,该方式很好地避免了现场高温和水淋对检测元件的损害,提高了元件的可靠度。经过对一起故障的排查、分析、处理,发现了该系统存在的不完善地方,提出了解决办法。

16m双柱立车在核电汽轮机低压内缸研制中的必要性分析

本文根据自主型核电汽轮机低压内缸结构、尺寸、重量、精度,加工现状,以及核电汽轮机发展趋势和市场前景,提出了添制16 m双柱立车在核电汽轮机低压内缸研制中的必要性,同时拟定了机床的主要技术参数。

自主核电汽轮机低压内缸研制技术探究

为了提高在制自主核电汽轮机低压内缸研制水平,文章对缸的设计结构、制造工艺、加工机床等环节进行了深入剖析,拟定出缸的结构优化、工艺完善、立车改造方案,有效提高了缸的研制质量,大幅降低了缸的研制费用。先进的技术方案、优良的经济效果,为机组进一步抢占国内外市场和公司目前推进的智能制造创出了一条新思路。

压缩天然气用环缠绕复合气瓶泄漏原因分析

针对某压缩天然气缠绕复合气瓶在使用不久后发生泄漏,采用化学成分分析、力学性能检验、金相检验、电镜观察等手段,分析了泄漏原因。结果表明:气瓶泄漏的原因是在充装使用过程中混入了水分,天然气中混有的H_(2)S、CO_(2)和氯化物溶于水滴后形成酸性溶液与瓶壁金属发生了电化学腐蚀,形成局部点状腐蚀,加上腐蚀和应力损伤持续进行,最终导致气瓶内壁穿孔失效,引起泄漏。

PCCP管芯混凝土防裂控裂技术研究进展

预应力钢筒混凝土管(PCCP)在我国引调水工程中发挥着重要作用,PCCP运行的安全性对水资源的配置至关重要,关系国计民生。当管芯混凝土内表面产生有害裂缝后,在水压力的作用下会引起内管芯混凝土破坏,导致钢筒被锈蚀,形成安全隐患,因此,针对管芯内壁混凝土裂缝预防和控制的研究对水资源的合理利用具有重大意义。为了预防和减少PCCP内壁出现有害裂缝,根据国内外学者的研究成果,概述了PCCP管芯内壁混凝土裂缝的种类和形式,即纵向裂缝、螺旋裂缝和插口端裂缝;总结了干燥收缩、沉降收缩、温度收缩、焊缝、缠丝应力、吊装运输等因素与PCCP内壁混凝土裂缝的关系;分别从PCCP设计、原材料、配合比、养护制度、焊缝、钢筒、插口和裂缝自愈合、纤维增强材料等方面总结了PCCP管芯内壁裂缝的预防和控制方法。最后,对PCCP管芯混凝土内壁裂缝的控制和预防进行了展望,为继续研究提供思路。

复合材料气瓶缠绕层的内部缺陷检测

复合材料气瓶具备质量轻、强度高、耐腐蚀与疲劳性能好等优势,但目前针对复合材料气瓶检验的国家标准主要以宏观检查为主,内外表面缺陷以及缠绕层的内部缺陷难以检出。分析了内部缺陷对复合材料气瓶的影响,对比并分析了3种缠绕层内部缺陷的检验方法,以期为复合材料气瓶的定期检验提供一定参考。

双螺杆挤出机异形内筒结构强度影响因素分析

异形内筒的厚度δi、相交圆中心距e、相交圆直径d是影响双螺杆挤出机强度的3个主要结构参数(简称3因素),一次局部薄膜应力PL、一次局部薄膜应力+二次应力P_(L)+P_(b)+Q是压力容器应力强度评定的2个主要应力类别。对3因素设定4个水平,进行3因素4水平正交试验,利用极差分析方法与方差分析方法处理正交试验数据。研究结果表明,因素δi、e、d对双螺杆异形内筒上危险截面处的应力P_(L)、P_(L)+P_(b)+Q均具有显著影响,对PL影响的主次排序为δi、e、d,对P_(L)+P_(b)+Q影响的主次排序为δi、d、e,对PL、P_(L)+P_(b)+Q影响的最佳方案均为δi(4)d(1)e(1)。采用多元回归分析拟合出了异形内筒结构危险截面应力PL及P_(L)+P_(b)+Q的多元回归方程,可用于双螺杆挤出机异形内筒结构应力的估算。

缸体铸件气孔缺陷成因分析及改进措施

2.5 L柴油机缸体铸件在工艺验证和小批量生产阶段,水套部位气孔为最突出的铸造缺陷,主要是由于水套砂芯发气未有效排出和水套结构孤立高点铁液温度低所致。通过增加内浇道优化浇注系统、设置排气通道回路增加水套砂芯排气、提高浇注温度等措施,有效解决了水套的气孔缺陷问题。经生产验证,气孔缺陷废品比例大幅度下降,由原来的11%左右下降到了0.6%左右。

Magneto-Hydro-Convective Nanofluid Flow in Porous Square Enclosure

In this work,a steady mixed convection in a two-dimensional enclosure filled viananoliquid Cu/H2O through a porous medium was numerically analyzed.The nanoliquid flow is designated utilizing the Brinkman-Forchheimer model.The upper and the bottom horizontal walls are considered to be hot(Th)and cold temperature(Tc),respectively,whereas the other walls are thermally insulated.The impact of various dimensionless terms such as the Grashof number(Gr)in the ranges(0.01–20),the Reynolds number(Re)in the ranges(50–500),the Hartman number(Ha)in the ranges(0–20),and three different location cases(0.25,0.5,and 0.75)are carefully analyzed.The obtained outcomes are established in the form of isotherms,streamlines,and the average Nusselt number.It has been found that heat transport increases significantly through rising Reynolds number(Re).For the location cases L=0.25,Re=50,and Gr=105,the heat transfer is maximum.

Radially loading rotary extrusion for manufacturing large-size conical cylinders with inner transverse high ribs

The Large-size Conical Cylinders with Inner Transverse High Ribs(LCCWITHR) can reduce the weight of the parts while maintaining high rigidity and strength. Radially Loading Rotary Extrusion(RLRE) forming technology can achieve integral forming of LCCWITHR through the synergy of radial and rotary movements of dies. The flow law of the material during the forming process is the key to forming large-size inner ribs. At present, there is no unified understanding of the metal flow law of RLRE forming technology. An analytical expression was derived to predict the Radial Direction(RD) deformation loads. The FE simulation and process experiment were carried out to investigate the effects of the inclination angle, thickness factor and transition arc radius of the split top dies on the spacing of the metal diversion plane, the metal flow velocity of the rib area and the final radius of the inner rib. The influence of the split top dies loading distance and the bottom die rotation angle of each pass on the inner radius of the inner rib was verified. And the optimal combination of dies shape parameters and loading paths which can make the metal flow orderly was obtained: the inclination angle is 140°, the thickness factor is 3.64, the transition arc radius is 16 mm;the top dies loading distance is 15 mm, the bottom die rotation angle is 45°.The FE simulation results have been found to be in close agreement with physics experiment.The research results reveal the metal flow law of rib growth in the RLRE of LCCWITHR, which lays a theoretical foundation for subsequent thorough research and process optimization.

加氢反应器筒节内径测量结果的不确定度评定

加氢反应器筒节的内径是在卷板机上加工完成的,筒节的内径尺寸直接关系到后续塔盘等部件的安装,因此其内径尺寸及圆度是需要重点控制的项目。本文重点对用内径千分尺测量筒节内径的测量的不确定度进行了分析评定。

汽车发动机缸体内腔质量影响因素分析及工艺控制

随着汽车轻量化的发展,发动机缸体壁厚要求越来越薄。针对水套内腔质量的影响因素进行了分析和工艺改善;介绍了烧结陶瓷砂、纤维素和铬尖晶石用于硅砂制芯添加对砂芯高温和常温特性以及产品质量的影响;指出涂料的热暴、热膨胀和烧结性对产品内腔质量影响以及涂料粉料的作用机理;运用射砂模拟技术对砂芯致密性进行了分析和质量改善。

缸体类零件内腔硬质阳极氧化加极装置设计与改进

[目的]某型号压气缸在现场安装时出现过盈配合问题,内腔硬质阳极氧化膜厚度分布不均及顶部膜厚过大是主因。[方法]设计并制作了加极装置,结合阳极氧化试验和有限元分析对其中的辅助电极进行改进。[结果]使用加极装置后,内腔阳极氧化膜厚度分布均匀,都在要求的10~20μm范围内。[结论]在硬质阳极氧化过程中使用合适的加极装置有利于控制缸体零件内腔阳极氧化膜的厚度,提高膜厚均匀性。

转台步进式钢瓶内壁喷丸清理机的研发

针对小口径钢瓶内壁上存在的氧化皮等杂质,介绍了一种转台步进式喷丸清理机,阐述了该喷丸清理机的工作原理、主要组成结构、技术关键及其解决方案,为钢瓶内壁清理提供了一种简单、高效、实用的方法。

液压支架油缸内壁腐蚀原因及防腐措施研究

液压支架油缸内壁腐蚀是一个普遍存在的问题,可能由介质腐蚀、摩擦磨损和化学反应等因素引起。针对腐蚀原因,研究人员提出了多种油缸内壁防腐措施来提高油缸内壁的耐腐蚀性能。常见的防腐方法包括表面涂层和嵌套不锈钢套等,表面涂层可以形成保护层,防止介质直接接触到金属表面;嵌套不锈钢套则是将不锈钢套嵌入油缸内壁,提供额外的保护层,提高油缸的耐腐蚀性和耐磨性。这些防腐措施的研究对于提高液压支架油缸的可靠性和使用寿命具有重要意义。