普通碳素钢椭圆形封头压制工艺的探讨

封头是锅炉、化工设备上的重要部件，在锅炉压力容器中所见的椭圆形封头、半球形封头、碟形封头和拱形盖中，以椭圆形封头最为常见。封头的制造方法有很多种，但在工业生产中主要采用在液压机上冲压和在旋压机上滚压两种方法。在液压机上冲压封     

凸形封头壁厚计算公式的分析

通过弹性力学分析,采用抛物线插值公式,得到了旧标准JB2194—77与新标准GB9222—88中的凸形封头强度计算公式。对按两个公式计算的凸形封头计算壁厚作了比较,认为按新标准设计的封头较旧标准安全。     

ASMEⅧ-2凹面受压椭圆封头计算浅析

本文以某产品为例,对ASME规范第Ⅷ卷第二册中凹面受压的椭圆形封头设计计算进行了简要阐述,分析了封头计算厚度大于简体计算厚度的原因,及设计计算中主要考虑的因素.     

压力容器球形封头与简体连接结构分析

球形封头是压力容器中常用的封头形式,其壁厚与简体壁厚相差较大,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,得出球形封头与简体连接应遵循的基本原则。     

碟形封头有限元应力分析及水压试验破坏原因研究

对按常规方法设计的受内压碟形封头进行了有限元应力计算。通过对计算结果的分析，讨论了碟形封头的应力状态和失效形式，对液压试验情况下按常规方法设计的碟形封头容易发生破坏的原因进行了研究。     

椭圆形封头大开孔结构强度分析

根据椭圆形封头的结构特点和工作条件,运用有限元分析方法,对大开孔椭圆形封头结构进行了应力分布计算与分析;进行了缩比模拟试验件静态应力实测及实验验证分析。计算和实验结果表明,该结构的危险部位为薄壁大接管与封头相贯顶部内侧,可作为设计的主要控制点;有限元计算外侧高应力区应力与实测结果相符,误差仅为0.7%,焊缝及内表面计算值与实测值误差大一些,但不超过11.3%。表明了利用三维有限元分析方法解决大开孔封头的结构设计是可行、可靠的。误差较大的原因分析可以为实际产品的设计、加工及实验提供一定的参考。     

仿形旋压封头液压活动模板的设计研究

对仿形旋压封头的液压活动模板的设计理论进行了研究和探索，首次得出了渐开线型活动模板有关参娄物确定方法，据之设计出了φ２０００×１５ｍｍ封头的仿形活动模板，可为其它旋压件旋轮运动轨迹的确定提供参考。     

椭圆封头表面积计算公式的讨论

通过对椭圆封头表面积的两个公式的推导及数值验算,得出JB4746-2002给出的公式为精确计算公式,并分析另一公式误差存在的原因及与影响误差大小的因素。     

谈谈对锅筒封头设计计算时的几点认识

锅炉锅筒封头的强度计算按GB／T9222标准,球冠形封头国内从88年起就不用了,主要原因是受力情况较差,但ASME规范允许使用。笔者主要介绍在选用封头强度计算时,应加强对封头结构要求的理解,同时选用合理的计算结果。下文主要介绍GB／T9222标准和ASME范围对凸形封头计算和标注的结构要求的分析。     

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。     

椭圆封头压制过程中易产生的各类缺陷分析

借鉴各制造厂的实际经验和压制工艺,对椭圆封头压制中易产生的各类缺陷进行了分析。     

Flow behavior of non-spherical particle flowing in hopper

Ellipsoidal particles flowing in the hopper were simulated by using the discrete element method (DEM), and described by the multi-element method. The contact detection algorithm and equations for ellipsoidal particle motion in hopper were developed. And the simulation results were confirmed by experiment. Additionally, the mass flow rate, pressure distribution and velocity distribution of two kinds of particles were examined. The results show that the mass flow rate of ellipsoidal particles is smaller than that of spherical particles. There is a maximum value of pressure drop at the top of the junction. Besides, the pressure drop decreases with the discharging time increasing. The velocity of spherical particle is larger than that of ellipsoidal.     

An explicit analytical solution for temperature rise in a half-space induced by ellipsoidal inclusions and its application for problems related to friction heating

Abstract

Green functions for temperature rise in a semi-infinite space containing an ellipsoidal inclusion are obtained in the present study. Explicit expression for disturbed temperature rise generated by eigen-temperature gradients uniformly distributed within a domain is derived. Further, the proposed analytical solution method is utilized to deal with temperature rise in heterogeneous half-space subjected to friction heating via applying the equivalent inclusion method (EIM), whose results are proven to be in good agreements with those of the benchmarks. Influences of heat load velocity, spatial orientation and aspect ratio of ellipsoidal inhomogeneity on temperature rise in a semi-infinite space are discussed. Finally, a model of semi-infinite medium with embedded dispersed ellipsoidal inhomogeneities of arbitrary spatial orientation is adopted to explore the application scope of the proposed solution method.     

立管内椭球颗粒群强化传热特性模拟研究

为提高液固两相流传热效率，通过添加椭球形颗粒改善立式换热管内液固两相流分布，采用CFD-DEM数值模拟颗粒长径比β、颗粒进口体积分数α以及流体进口速度v与管内椭球形颗粒群传热的关系，并根据PEC指数评价颗粒强化传热能力。模拟结果表明：在1.5≤β≤2.5，2％≤α≤4％，1.0m/s≤v≤1.5m/s参数内，椭球形颗粒PEC指数总高于球形颗粒，即前者强化换热效果优于后者。     

压力容器圆筒与凸形封头连接的边界效应分析及比较

本文阐述压力容器圆筒与半球形封头、椭圆封头连接时的边界效应及二者的比较,并用应力分析云图形象的说明了连接处的变形情况。     

锅筒椭圆形封头人孔板边过渡圆弧制图的数学模型

推导出确定锅炉锅筒椭圆形封头人孔板边过渡圆心坐标的公式,可供计算机绘图时的参考。     

椭圆锥稳燃器对煤粉火焰的稳燃作用

引入气固两相流的特性参数,从煤粉气流结构出发,分析了椭圆锥稳燃器对煤粉火焰的稳燃作用。     

水平浓淡煤粉燃烧器内气固两相流的数值模拟

为了揭示煤粉气流在带有弯管、方圆接头、可调浓淡煤粉分离装置及喷口前直管段内的运动轨迹及分离机理,将新型可调水平浓淡煤粉椭圆锥燃烧器喷口前弯管、方圆接头、可调浓淡煤粉分离装置及直管段作为整体,采用RNGK ε模型和随机轨道模型,通过颗粒与流体耦合的PISC算法,对管内气固两相流进行了数值模拟。模拟结果表明弯管是一种经济而有效的煤粉分离装置,可调浓淡煤粉分离装置可调节燃烧器向火侧和背火侧的煤粉浓度,为其进一步完善和广泛应用提供了理论依据。图4参9     

Cooling characteristics of an impinging spray jet which forms an ellipsoidal liquid film

The cooling characteristics of an impinging spray jet which forms an ellipsoidal liquid film were experimentally investigated in order to estimate the cooling performance of a rotating roll in a hot mill system. The following four conclusions were reached in the study. (1) In the case of a single spray jet, the local heat transfer coefficient at the center position depends on the forced convective heat transfer by the impinging jet. However, the average heat transfer coefficient is proportional to the flow rate density of the cooling water, and it does not depend on the distance between the nozzle and heated surface. (2) In the case of a double spray jet, liquid film interference occurs. The local heat transfer coefficient at the center position is greater, and the cooling performance increases with the increasing flow rate density of the cooling water. (3) The cooling performance of a multispray jet is proportional to the flow rate density of the cooling water. It does not depend on the nozzle construction, distance, or specifications. Also, there is no relation to the liquid film interference. (4) When the optimum specifications of the spray nozzle are used, thermal analysis of a rotating roll shows that the temperature at a depth of 1.3 mm from the surface is below 130 °C. © 2000 Scripta Technica, Heat Trans Asian Res, 29(4): 280–299, 2000