压力容器球形封头与筒体连接结构分析

球形封头是压力容器中常用的封头形式,其壁厚与筒体壁厚相差较大,GB150-1998中将筒体与球形封头的对接环形焊缝定义为A类焊接接头。本文从壁厚计算公式角度出发,讨论了工程中常用的球形封头与筒体的连接结构及其合理性,得出球形封头与筒体连接应遵循的基本原则。     

锅筒封头壁厚公式的力学分析

对常用的封头壁厚公式进行了力学分析，并对两种类型锅炉的封头壁厚公式进行比较。     

超高扬程垂直升船机塔柱结构型式及抗震性能分析

为确定升船机塔柱结构筒体尺度,将高扬程升船机塔柱结构简化为薄壁筒体结构,控制塔柱顶部位移满足相关规范要求,基于悬臂梁法,编写程序计算筒体宽度与壁厚之间的关系。根据塔柱结构设计原则和使用要求,在保证混凝土用量相近的条件下,拟定了固定壁厚、变壁厚两种超高扬程塔柱结构型式尺度;采用ABAQUS有限元软件建立了固定壁厚和变壁厚两种塔柱结构计算模型,分析了超高扬程大型升船机塔柱结构在三种不同烈度地震荷载下的动力响应。计算结果表明,在不同地震烈度作用下,变壁厚塔柱结构的顶部位移及加速度、惯性力、筏形基础的拉、压应力较小,变壁厚塔柱结构的抗震性能优于固定壁厚塔柱结构。     

16ГНМ汽包的爆破试验

420吨/时锅炉的汽包参数为155大气压,343℃(图1),由6只筒体组成,壁厚90毫米,内径1800毫米。包括封头在内的总长度为18米。汽包经28683小时的运行和158次停炉后,经仔细检查发现有许多缺陷,就从锅炉上拆下。主要     

专利信息

太阳热水器承压水箱本实用新型为一种改进的太阳热水器承压内水箱，它由内水箱筒体、球形封头、连接管组成。其特征是，内水箱筒体加工有波纹加强筋，其下部加工有安装太阳能真空集热管的圆孔，球形封头焊接在内水箱筒体两端，水箱的箱体采用不锈钢钢板加工而成。这种水箱设计合理、承压防漏、造价低，是一种理想的太阳热水器内水箱的替代产品。（专利权人潜江博光太阳能开发有限责任公司授权公告号CN２４３６８９１Y）图１太阳光跟踪传感器本实用新型为一种太阳光跟踪传感器。它包括光信号接收器和分别连接反馈处理电路的４组信号输出端…     

带人孔加强圈的水管锅炉封头的开孔补强及有限元分析

《水管锅炉受压元件强度计算》标准未包含有关凸形封头利用孔的补强措施以减小封头壁厚的规定.但是对于带人孔加强圈的水管锅炉有孔封头,有时需要在封头的壁厚计算中体现加强圈的补强作用.利用有限元分析方法,对此类封头经开孔补强后的结构进行安全性验证,并探讨类似问题的解决办法.     

汽水分离再热器筒体泵水压力试验

1 重要性汽水分离再热器[MSR]是核电站二回路系统中的关键设备之一,它属压力容器范畴,该容器直径约为4米,长14.5米,用38毫米厚钢板(优质中碳钢板)滚制成筒体,两端焊上半圆形封头,因筒体上开了大小14处孔口,最大的直径约1.2米,大多数孔都开在筒体上须要补强外,筒体上焊缝全部做X光拍片检验存档,但高、低压加热器装入筒体两端封头内,焊接后焊缝无法做X光拍片检查。按照压力容器规范,必须做筒体强     

碳当量对活塞环铸件质量的影响

我厂活塞环车间生产的6300与6320大活塞环,是用三相电弧炉熔炼的。采用筒体铸造,小包浇注,每小包浇注两个。6300毛坯外径303mm,壁厚14mm,6320毛坯外径323mm,壁厚15mm,每个分别重约26kg和27kg。毛坯形状如图1所示     

开远300MW流化床锅筒工艺研究

本文介绍了国内首台在引进技术的基础上开发的300MW大型循环流化床锅炉-开远循环流化床锅筒,并介绍了开远循环流化床锅筒的结构特点以及简要的工艺制造流程,封头采用一次热压成形,简体采用压制成形或卷制成形,并解决了下降管接头的加工难题以及总装时的焊接难点,为大型循环流化床锅炉的制造留下了宝贵的经验。     

风力发电机组塔筒门段结构优化设计

文章提出了两种新的塔筒门段结构形式,一种是将门洞进行整体钢板切割,焊好门框后,再整体与塔筒段筒体焊接;另一种也是将门洞进行整体钢板切割,但取消门框,同时加厚门洞所在塔筒壁厚。两种结构静强度分析均满足设计要求,且塔筒段减重明显,为塔筒门段结构设计提供了参考。     

The strength and deformations of torispherical ends for glass-reinforced plastic pressure vessels—Part 2: Effect of torisphere geometry for ends of fixed head height

Four further glass-reinforced plastic cylindrical pressure vessels with torispherical dished ends have been tested to destruction. Together with two vessels already reported on in Part 1 of this paper, these specimens form part of a group with the same head height of 0·25 m but with three different torus radii of 0·1 m, 0·146 m and 0·188 m, giving crown radii of 0·71 m, 0·8 m and 1·0 m, respectively (two vessels of each geometry were tested). As in Part 1, results from the tests were compared with those suggested by the current UK design code (BS 4994) and the predictions of a computer-based elastic stress analysis (BOSOR 4). In contrast to BS 4994, BOSOR 4 indicates that there is little difference in strength between dished ends with the two larger knuckle radii. A torus radius of 0·1 m, however, does produce a significant increase of maximum stress and strain. In fact, of the four additional vessels tested, only those two of this latter geometry ultimately failed in the dished end, those of knuckle radius 0·146 m rupturing in the cylinder.     

On the shakedown analysis of nozzles using elasto-plastic FEA

The performed shakedown calculations of a dished end with a nozzle in the knuckle region with varying internal pressure load, and two cylinder–cylinder intersections with constant moment load and varying internal pressure load are example cases for the application of the check against progressive plastic deformation as stated in the new European UFPV standard, Annex 5.B: “Direct route for design by analysis” (DBA). To calculate the shakedown limits, Melan's (lower bound) shakedown theorem is used. In this context, the usage of the deviatoric maps of stress states to obtain proper self-equilibrating stress fields is shown. Furthermore, some problems and corresponding possible solutions for performing the shakedown check using a finite element model with shell elements are stated and shown in the examples.     

Design of pressure vessels using shape optimization: An integrated approach

Previous papers related to the optimization of pressure vessels have considered the optimization of the nozzle independently from the dished end. This approach generates problems such as thickness variation from nozzle to dished end (coupling cylindrical region) and, as a consequence, it reduces the optimality of the final result which may also be influenced by the boundary conditions. Thus, this work discusses shape optimization of axisymmetric pressure vessels considering an integrated approach in which the entire pressure vessel model is used in conjunction with a multi-objective function that aims to minimize the von-Mises mechanical stress from nozzle to head. Representative examples are examined and solutions obtained for the entire vessel considering temperature and pressure loading. It is noteworthy that different shapes from the usual ones are obtained. Even though such different shapes may not be profitable considering present manufacturing processes, they may be competitive for future manufacturing technologies, and contribute to a better understanding of the actual influence of shape in the behavior of pressure vessels.     

Numerical Investigation of Forced Convection Conjugate Heat Transfer from Offset Square Cylinders Placed in a Confined Channel Covered by Solid Wall

Flow over two isothermal offset square cylinders in a confined channel is simulated for different Reynolds numbers to disclose the forced convection heat transfer from the heated square cylinders to the ambient fluid. The spacing between the cylinder in the normal direction and the blockage ratio are fixed. The channel walls are covered by solid walls of thickness equal to the size of the cylinder and conjugate heat transfer is considered by including these walls. Heat transfer from the cylinders to the ambient fluid as well as that conducted within the solid wall through the conjugate interface boundary are investigated in connection with Reynolds number and are reported for both steady and periodic flows. Simulation is carried out for Reynolds number varying from 10 to 100 with air as the fluid. The onset of the vortex begins when the Reynolds number equals 48. The conjugate interface temperature declines when the Reynolds number grows. The isotherms in the solid wall show two dimensionality near the cylinder region.     

Numerical study of elliptical cracks in cylinders with a thickness transition

The paper deals with elliptical cracks in a cylinder with a thickness transition. This structure is an assembly of two cylinders of thickness t and t₂ (t<t₂). In the transition zone, the thickness varies linearly. The purpose is to check whether tabulated data used for SIF calculations in a cylinder of uniform thickness t can be used for the cylinder with a thickness transition. A comparative study is made on the effect of a crack in a cylinder with a thickness transition and in a uniform thickness cylinder. Loads considered are pure tensile stress and bending moment. A numerical analysis was performed considering elastic behaviour at the crack tip. A crack mesh was designed and validated for 3D models. The results show that SIF calculations in the transition assuming a uniform thickness cylinder are conservative but not precise. The comparative study shows that the cylinder with a thickness transition is more vulnerable to a defect.     

活塞环—缸套润滑状态周向不均匀性的研究

本文基于活塞环接触压力分布、活塞环偏摆、活塞环开口间隙位置的分析研究，指出了活塞环－缸套润滑状态周向不均匀性的客观存在。应用二维平均流量模型和微凸体接触方程，并考虑活塞系统的偏摆和润滑油粘度变化，提出了一个新的活塞环－缸套润滑状态的分析计算模型，给出了活塞环－缸套油膜厚度的三维分布，定量探讨了活塞环接触压力分布形状、活塞环偏摆、活塞环开口间隙位置对周向油膜厚度不均匀性的影响。     

柴油机缸内近气缸盖壁面边界层预测模型的研究

分析了缸内壁面速度边界层和热边界层的形成过程,建立了缸内近气缸盖壁面面湍流速度壁面函数和温度壁面函数,研究了边界层内的速度分布、温度分布及速度边界层厚度和热边界层厚度,并将预测结果与拖动发动机的实测值进行了比较,发现两的趋势是一致的。研究结果表明,缸内近气缸盖壁面有边界层形成,同一位置的速度边界层与热边界层的厚度很接近,不同位置的边界层厚度不同,大约在2mm-4mm左右。     

Stochastic Assessment of Thermo-Elastic Wave Propagation in Functionally Graded Materials (FGMs) with Gaussian Uncertainty in Constitutive Mechanical Properties

The main objective of this article is focused on stochastic analysis of wave propagation and effects of uncertainty in mechanical properties on transient behaviors of displacement and temperature fields in functionally graded materials under thermo-mechanical shock loading. The problem is studied in a cylindrical domain and the governing equations of a functionally graded thick hollow cylinder are solved. To assess the wave propagation, the generalized coupled thermoelasticty equations based on Green-Naghdi theory (without energy dissipation) are analyzed in a FG thick hollow cylinder. The FG cylinder is considered to have infinite length and axisymmetry conditions. The constitutive mechanical properties of FGM are assumed as random variables with Gaussian distribution and also the mechanical properties are considered to vary across thickness of FG cylinder as a nonlinear power function of radius. The FG cylinder is divided into many elements across thickness of cylinder and hybrid numerical method (Galerkin finite element and Newmark finite difference methods) along with the Monte Carlo simulation are employed to solve the statistical coupled equations. The effects of uncertainty in functionally graded materials on thermal and elastic waves, transient behaviors of radial displacement and temperature fields and variance and maximum values of displacement and temperature are discussed in details for various grading patterns in FGMs and various points on thickness at several times.     

均质充量压缩着火燃烧碳氢生成和边界层贡献的试验研究

试验研究了均质充量压缩着火(HCCI)燃烧过程中边界层区域HC生成、分布与消耗历程,考察了边界层各个区域对整体HC排放的贡献比例。为此,在快速压缩机上利用瞬态HC排放仪测量了均质混合气在当量比0.4、不同压缩比下靠近气缸盖底面和气缸体侧面不同距离的各测点在全反应历程内的HC浓度。研究发现:压缩比降低使得边界层效应更加明显;同一工况下,气缸盖底面和气缸体侧面的边界层厚度因受到压缩挤流和壁面传热的影响而不同,气缸体侧面的边界层效应比气缸盖底面的更加显著;靠近气缸盖底面和气缸体侧面2mm以内的区域对整体HC排放的贡献较高,气缸中心燃烧核心区域贡献较小。