内燃机曲轴不对中弹性支座连续曲梁弯曲强度的研究

本文是在连续组合梁法曲轴弯曲强度电算程式的基础上,以6130柴油机为例,所进行的分析与计算的结果。这种计算方法虽然是一种静态方法,但由于在连续梁法中采用了弹性的曲拐与曲轴支承以及主轴承支座具有下沉度等这样一些与发动机实际工况相一致的技术参数,从而使其计算结果在应力曲线的形状和许多点的弯曲应力值上能逼近于实际的动态工况,这些都已为一些实测的结果所证实。文中还提出了曲轴支座柔度值合理范围的计算方法,曲轴支座柔度值和主轴承支座下沉度选择与推定的方法,这些方法对保证计算精度有深刻的影响。     

冷凝式汽轮机排汽缸使用柔性支座的研究

柔性支座是我国工业汽轮机较少使用的一种支承方式，它与刚性支座有不同的特性和特点，本文通过以某排汽缸为例，建立柔性支座的有限元模型，从理论上用计算机软件 分析，计算，得出了使用柔性支座的可行性及其调整方法。     

球罐小直径支柱埋弧自动焊焊剂托架设计

一种球罐小直径支柱埋弧自动焊焊剂托架包括漏斗、薄弧板、挡板、橡胶密封垫、连接板和支座,其方法是将一些焊剂放置于薄弧板上面,然后将该托架放置于支柱焊缝正下方,使焊剂与外圆环向焊缝之间紧密贴合,从而解决了球罐小直径支柱内部环向焊缝无法直接采用埋弧自动焊焊接的问题。     

凸形管板的强度计算问题

文章介绍了凸形管板(拱形管板、椭球形管板)强度的有限元计算分析以及烟管对椭球形管板变形与应力的影响,并根据国内的大量有限元计算分析及国外规范中的有关规定,就椭球形管板及拱形管板的强度计算方法提出了建议。     

废热锅炉换热器管板结构有限元分析研究

用有限元分析方法 ,对带弓形不布管区废热锅炉换热器管板的结构进行有限元分析计算。在有限元分析模型中采用壳单元模拟管束、管板和筒体 ,采用杆单元模拟斜拉杆 ,并考虑管束对管板转角的约束。采用德国AD规范 ,计算管板厚度并比较两者的计算结果。通过分析可为工程优化设计提供依据。     

基于梁带法的大型电站凝汽器管板刚度计算分析

根据大型电站凝汽器管板刚度的计算需要,基于梁带法建立大型电站凝汽器管板梁带力学模型。通过在该力学模型端部添加等效弹簧来模拟钢梁对管板端部的刚性加强作用,并给出了端部弹簧刚度系数计算公式。采用矩阵位移法求解梁带力学模型,根据建模和求解过程开发大型电站凝汽器管板刚度计算专用软件。利用该软件分析管板厚度和端部钢梁对管板刚度计算结果的影响。结果表明:管板厚度和钢梁对管板刚度计算影响显著,增大管板厚度可显著减小管板最大应力,而增大端部钢梁等效弹簧刚度系数可显著减小冷却管、钢梁的最大变形。     

基于灵敏度分析的某型柴油机支座安装结构改进

本文针对某柴油机台架试验时振动烈度偏大的问题,利用ANSYS软件分析了安装支座的模态,并通过测试其速度导纳检验了支座有限元模型的精度.在此基础上对支座进行了结构设计的灵敏度分析.结果表明应用此方法对支座进行结构改进和优化后,对改善支座的动态特性是有效的.     

FRP筋混凝土双向板冲切承载力计算模型研究

为了得到较准确的FRP筋混凝土双向板冲切承载力的计算模型，以FRP筋混凝土双向板为研究对象，运用文献综述、数据统计、模型分析和回归计算等研究方法，借助常用的FRP筋混凝土双向板冲切承载力计算模型，对98块FRP筋混凝土双向板冲切试验数据进行计算和评估，并运用双向板临界冲切截面系数反演的方法，提出了一种新的FRP筋混凝土双向板冲切承载力的计算模型，该模型对FRP筋混凝土结构在集中荷载作用下冲切承载力的预测具有较高的精度，计算结果与试验数据库吻合较好。该研究对FRP筋混凝土双向板冲切承载力的设计具有指导意义，并对今后进一步提高FRP筋混凝土双向板冲切承载力计算模型的精度提供了重要参考。     

对Ar存储器的应力分析

采用有限元分析软件ANSYS Mechanical 11.0,根据ASME锅炉与压力容器规范对压力容器计算的要求[1],对上海锅炉厂有限公司设计制造的Ar存储器进行应力分析,包括本体、支座、接管和人孔的弹塑性分析,支座的失稳分析等[1-2]。并根据各类分析内容进行整体和局部的应力评定,以确定此Ar存储器的设计符合2013版本ASME锅炉与压力容器规范的相关要求。     

医院中央空调用能的诊断及改造技术

一种球罐小直径支柱埋弧自动焊焊剂托架包括漏斗、薄弧板、挡板、橡胶密封垫、连接板和支座,其方法是将一些焊剂放置于薄弧板上面,然后将该托架放置于支柱焊缝正下方,使焊剂与外圆环向焊缝之间紧密贴合,从而解决了球罐小直径支柱内部环向焊缝无法直接采用埋弧自动焊焊接的问题。     

定温差直流式太阳能热水系统不同工况下的数值模拟与分析

直流式太阳能平板集热系统的运行过程可认为是由启动时的闷晒阶段和达到出水温度时的连续放水阶段组成。运用fluent数值模拟软件建立管板式平板集热器的物理模型,对该过程进行数值模拟,并将模拟结果与理论计算进行了对比分析,得出了平板集热器效率的变化趋势。     

广义位移法在硗碛心墙堆石坝三维静力分析中的应用

将广义位移法应用于硗碛砾石土心墙堆石坝三维静力计算分析,用板、梁单元模拟防渗墙和廊道原结构的力学机制和几何特性,减少了模型自由度,提高了计算效率。同时将六面体单元与板、梁单元对比分析,两种计算结果基本吻合,防渗墙和廊道的位移和应力分布规律和数值均能满足要求。     

Effect of Duct Geometry on Shock Wave Discharge

This paper describes computational work to understand the unsteady flow-field of a shock wave discharging froman exit of a duct and impinging upon a flat plate.A flat plate is located downstream, and normal to the axis of theduct.The distance between the exit of the duct and fiat plate is changed.In the present study,two different ductgeometries(i.e.,square and cross section)are simulated to investigate the effect of duct geometry on theun-steady flows of a shock wave.In computation,the total variation diminishing(TVD)scheme is employed tosolve three-dimensional,unsteady,compressible,Euler equations.Computations are performed over the range ofshock Mach number from 1.05 to 1.75.Computational results can predict the three-dimensional dynamic behav-iour of the shock wave impinging upon the flat plate.The results obtained show that the pressure increase gener-ated on the plate by the shock impingement depends on the duct geometry and the distance between the duct exitand plate,as well as the shock Mach number.It is also found that for the duct with cross-section,the unsteadyloads acting on the flat plate are less,compared with the square duct.     

Study on forced air convection cooling for electronic assemblies

The slotted fin concept was employed to improve the air cooling performance of plate-fin in heat sinks. Numerical simulations of laminar heat transfer and flow pressure drop were conducted for the integral plate fin, discrete plate fin and discrete slotted fin heat sinks. It is found that the performance of the discrete plate fin is better than that of the integral continuum plate fin and the performance of slotted fin is better than that of the discrete plate fin at the same pumping power of the fan. A new type of heat sink characterized by discrete and slotted fin surfaces with thinner fins and smaller spaces between fins is then proposed. Preliminary computation shows that this type of heat sink may be useful for the next generation of higher thermal load CPUs. The limit of cooling capacity for air-cooling techniques was also addressed.     

过渡段部分对某高压压气机性能影响研究

以某型高压九级轴流压气机为研究对象,通过NUMECA软件进行模拟计算,研究了前过渡段、过渡段支板和出口过渡段的气体流动损失对压气机性能的影响,并采用DFFD参数化方法和多岛遗传算法对过渡段部分进行了结构改型与气动优化设计。结果表明:相比不带过渡段的压气机模型,原型过渡段使等熵效率降低1.57%,经过对过渡段型线改进以及对过渡段支板的优化设计,优化后过渡段使等熵效率仅降低0.63%;优化后的过渡段部分气流阻塞减少、损失减小,使得高压压气机整体效率较优化前提高0.94%;经流场损失分析发现,支板段和出口扩压延长段是造成堵塞和效率降低的主要原因。     

Logarithmic Mean Pressure Difference—A New Concept in the Analysis of the Flow Distribution in Parallel Channels of Plate Heat Exchangers

This paper deals with a new concept of logarithmic mean pressure difference (LMPD) to find an accurate mean or true friction coefficient for variable flow in parallel flow channels of the plate heat exchangers while considering the first and the last channel pressure drops. This is analogous to the log mean temperature difference (LMTD) used for the computation of heat transfer in heat exchangers. A method has been suggested to improve the computation of mean or a newly defined “true friction factor” and the mean velocity for considerable flow variations in the channels. A comparative study has been made between the conventional average friction factor and the true mean friction factor for large parallel channels. The results have also been compared between the mean channel pressure drop and LMPD for different sizes of the channels. The analysis shows that the mean channel pressure drop of parallel channels can be predicted accurately by using the so-called true mean friction factor rather than the average friction factor. Using the LMPD method, one can find the last channel pressure drop by knowing the first channel pressure drop of the plate package. Hence, the nature of flow distribution in parallel channels can be predicted easily.     

闸坝地基面渗透压力研究

应用渗流理论的解析解研究了闸坝地基面渗透压力的分布规律，求出渗透压力的合力大小和作用点位置，分析了地基深度和下沉平底板下沉深度对渗透压力分布的影响；并与传统的简化计算方法作了比较。     

折流式动力电池液冷板流动传热性能强化

发展新能源汽车是助力“双碳”战略的有效措施之一,动力电池的热安全和热衰减问题制约了新能源汽车的发展。针对这一问题设计折流式动力电池液冷板,研究结构参数对其流动传热特性的影响,对比不同局部连通方式的优化效果。结果表明,折流板长且多的冷板具有更好的综合换热性能,局部连通结构能够同时提升折流式冷板的综合换热性能和温度均匀性,增加连通口数量及最后连通口与流道拐角的距离能够进一步提升优化效果,最大分别可提升25.62%和7.84%。     

Shell side heat transfer characteristics with an eggcrate support plate for water in parallel flow

The shell side heat transfer and pressure drop for water in parallel flow with an eggcrate support plate were experimentally investigated in order to obtain higher performance for the heat exchanger in a boiling water reactor power plant. The following three conclusions were reached. (1) The shell side heat transfer characteristics with the eggcrate support plate were twice as large as those of the shell side parallel flow. An equation using the Reynolds number of the eggcrate support plate could predict the heat transfer coefficient. (2) The shell side pressure drop characteristics with the eggcrate support plate were about five to six times as large as those of shell side parallel flow. (3) The enhancement constant of heat transfer with the eggcrate support plate, using Colburn's j‐factor and friction factor f, was the same as that of the ROD‐baffle type, and was about two times as large as that of the segmental baffle type. © 2000 Scripta Technica, Heat Trans Asian Res, 29(2): 91–112, 2000     

Radiation effect on MHD flow past a porous vertical plate in the presence of heat sink

This study investigates heat and mass transfer in MHD convective flow through a vertical plate via porous media in the presence of radiation and a heat source/sink. It is assumed that a uniform magnetic field of strength is imposed perpendicular to the plate and directed into the fluid area. The governing nondimensional equations are solved using the perturbation technique. We further derived the skin friction, Nusselt number, and Sherwood number. The computation of results is performed with the aid of mathematical software and results are presented in graphical and tabular forms for distinct flow impacting parameters. It is observed that fluid motion is retarded due to the application of the magnetic field. Furthermore, the fluid temperature comprehensively falls under the Prandtl number as well as the thermal radiation effect. It is important to note that the heat sink causes fluid velocity and fluid temperature to fall drastically.