多层组合圆筒体的轴对称温度和热应力的通用计算方法

根据圆筒体轴对称导热的分析原理,推导了多层组合圆筒轴对称导热温度分布和热应力的通用计算式方法,多层组合圆筒体的内部界面温度和径向压力的三对角型方程组形式,给出了计算流程,编写了相应的计算程序,给出了算例.     

高炉炉缸冷却壁对流换热边界的等效置换与导热模型化简

根据固体导热理论讨论大平板和平面轴对称圆筒中对流边界的等效置换问题.利用有限元计算了高炉炉缸冷却壁中水管表面的对流换热边界向内部边界等效置换,给出了算法和计算实例.对流换热边界置换后可使冷却壁一炉墙结构的平面导热问题化为一维问题.     

全纤维炉衬的稳定态传热计算

用通常的方法作稳定态传热计算时,须先假设各层温度,由此求得各层导热系数,最后验算所假设的温度与计算值是否相近,如差得太多就得重算。耐火纤维的导热系数随温度而剧烈变化(图1),温度每增数百度,导热系数就增大一倍,用通常的方法计算全纤维多层炉衬时,常常需要反复多次假设及计算。     

工业炉炉墙厚度的数值解法

本文分析了工业炉炉墙的不稳定导热，提出了多层炉墙设计的数值解法公式，用实例说明用这种方法计算出的炉墙温度与实测值相差不大，所以实际设计时，可用本文提供的公式。稳定导热是不稳定导热散热量的２．２７倍，因此不考虑不稳定导热会造成很大的浪费。     

水射流冲击冷却过程靶面热流密度测试方法的改进

为了准确测量水射流冲击冷却过程靶面热流密度,提出在靶体背侧增加绝热材料,采用单点测温,使用一维导热反问题计算靶体表面热流密度的方法.实验数据分析显示,采用该方法对靶体背侧温度预测的相对误差±5%以内的概率为93%以上,由于靶体背侧仅是近似的绝热条件,导热反问题计算的靶体背侧温度略高于实测温度.结果表明,通过在靶体背侧增加绝热材料,即便采用单点测温,仍然可以很容易地获得足够精确的靶体温度和表面热流密度.     

新型圆筒混合机设计的探讨

针对大型圆筒事机筒体直径大，制造，运输困难的问题，通过计算提出了一种采用小直径圆筒的设计思想，并对设备结构提出了相应的改进意见。     

铝电解槽覆盖料导热性能测试及散热分析

电解槽一半以上的散热量经由电解槽上部覆盖料层后，从烟气、槽罩和上部结构散出；而上部散热中，覆盖料层的热阻权重较大。拟采用平板导热仪测试电解槽覆盖料导热系数，以指导电解槽的设计与生产。对阳极上的破碎覆盖料、新鲜氧化铝粉进行取样及导热性能测试，对比了不同粒径的覆盖料导热性能，同时分析了不同阳极高度下电解槽覆盖层温度及散热。本文对电解生产管理在电解槽覆盖料粒径、配比、覆盖层厚度等精细化管理的选择上提出一定的建议，并建设性给出了一种新型的铝电解槽阳极覆盖方法。     

更逼真的耐火衬特性曲线热模型

耐火材料使用者和供应者的习惯做法,是假定每层耐火衬都是呈线性温度梯度,并使用各层平均温度下的当量导热系数来计算通过炉衬的热流。然而实际上绝大多数耐火材料的导热系数不是常数,所以通过任一层耐火衬的温度梯度也不是线性的。用平均温度法计算冷面温度、热流和蓄热量时误差很明显,特别是用陶瓷纤维块做单层衬时更是如此。     

Excel在稳念导热计算中的应用

以多层壁稳态导热计算新方法为基本方法，运用Excel进行数据的辅助计算。结果表明，Excel运算迅速、准确，编制一次即可重复运用。     

灰介电膜传热研究

用Boltzmann传输方程建立灰介电薄膜声子辐射传热方程，提出灰体介电薄膜的当量导热系数的概念，指出Fourier定律只适用于声学极厚区域，给出了用Fourier定律进行热流密度计算的误差。     

General Temperature Computational Method of Linear Heat Conduction Multilayer Cylinders

 According to the axisymmetric heat conduction of cylinder, a general method to calculate the axisymmetric temperature of linear heat conduction multilayer cylinder is deduced. Boundary conditions are summed up to four types and formulas under each type are derived. Tridiagonal linear system eouations of internal temperature are solved with pursuit method. Meanwhile, the calculating program of the simulation program is developed and the corresponding computation program and an example are given.     

General Temperature Computational Method of Linear Heat Conduction Multilayer Cylinder

According to the axisymmetric heat conduction of monolayer cylinder,a general method was deduced to calculate the axisymmetric temperature of linear heat conduction multilayer cylinder.Four types of boundary conditions were summarized and formulas for each type were derived.Then,a general calculating program was developed.Four temperature formulas could be expressed by a uniform equation,and the intermediate interface temperatures of axisymmetrical linear conduction multilayer cylinder satisfied tridiagonal...     

A model for the time-dependent thermal distribution within an iceball surrounding a cryoprobe

The optimal cooling parameters to maximize cell necrosis in different types of tissue have yet to be determined. However, a critical isotherm is commonly adopted by cryosurgeons as a boundary of lethality for tissue. Locating this isotherm within an iceball is problematic due to the limitations of MRI, ultrasound and CT imaging modalities. This paper describes a time-dependent two-dimensional axisymmetric model of iceball formation about a single cryoprobe and extensively compares it with experimental data. Thermal histories for several points around a CRYOprobe are predicted to high accuracy (5 degrees C maximum discrepancy). A realistic three-dimensional probe geometry is specified and cryoprobe temperature may be arbitrarily set as a function of time in the model. Three-dimensional temperature distributions within the iceball, predicted by the model at different times, are presented. Isotherm locations, as calculated with the infinite cylinder approximation, are compared with those of the model in the most appropriate region of the iceball. Infinite cylinder approximations are shown to be inaccurate when applied to this commercial probe. Adopting the infinite cylinder approximation to locate the critical isotherm is shown to lead the user to an overestimate of the volume of target tissue enclosed by this isotherm which may lead to incomplete tumour ablation.     

Thermoelastic Analysis of Functionally Graded Ceramic-Metal Cylinder

The pseudodynamic thermoelastic response of functionally graded ceramic-metal cylinders is studied. This paper presents the finite-element formulation of the 1D, axisymmetric heat transfer equation and the thermoelastic radial boundary value problem. A two-step solution of the governing equations of thermoelasticity is presented. Thermoelastic coupling is considered by taking into effect the temperature dependence of the constitutive equations. Nonlinearity due to the temperature dependence of the material properties of the constituent ceramic and metal is considered. A parametric study with respect to varying volume fraction of the metal is conducted. Temperature and radial∕hoop stress distributions arising due to rapid heating of the inner surface of the functionally graded cylinder are presented.     

Solidification front shape of the molten metal in a thermally thin cylinder

Reported data are reviewed briefly. When a molten metal is extruded to produce a wire directly from the melt, a capillary stream 0.2–3 mm in diameter is directed into a cooling medium so that external heat exchange ensures faster solidification of the metal as compared to capillary disintegration of the stream into drops. The following two assumptions regarding the shape of the solidification front exist: a planar solidification front normal to the axis and a curved axisymmetric front surface. Both assumptions are considered. The assumption of a curved axisymmetric solidification front surface of the molten metal in a cylinder is shown to be more realistic.     

Radiation Hydrodynamics of Floating Vertical Cylinder in Viscous Fluid

Fully nonlinear axisymmetric viscous flow due to heave oscillation of a surface-piercing vertical cylinder is analyzed using a finite-difference method based on curvilinear coordinates. Of significance to numerical modeling is the present finding that the free-slip condition used to model the movement of the contact line affects neither the overall flow nor the hydrodynamic pressure force acting on vertical cylinder. The viscous-flow results are compared with fully nonlinear inviscid-flow results, which are obtained using a mixed Eulerian-Lagrangian formulation, to contrast the effects of viscosity on the flow field, hydrodynamic force, and radiating surface waves. New results are presented for a range of parameters to illustrate physical mechanisms of the inception and evolution of vertical structures due to body motion in a free surface and their effects on the hydrodynamic force.     

Analytical Approach to Predicting Temperature Fields in Multilayered Pavement Systems

An accurate and rapid estimation of the pavement temperature field is desired to better predict pavement responses and for pavement system design. In this paper, an innovative method to derive the theoretical solution of an axisymmetric temperature field in a multilayered pavement system is presented. The multilayered pavement system was modeled as a two-dimensional heat transfer problem. The temperature at any location (r,z) and any time t in an N-layer pavement system can be calculated by using the derived analytical solution. The Hankel integral transform with respect to the radial coordinate is utilized in the derivation of the solution. The interpolatory trigonometric polynomials based on discrete Fourier transform are used to fit the measured air temperatures and solar radiation intensities during a day, which are essential components in the boundary condition for the underlying heat transfer problem. A FORTRAN program was coded to implement this analytical solution. Measured field temperature results from a rigid pavement system demonstrate that the derived analytical solution generates reasonable temperature profiles in the concrete slab.     

加热炉炉门提升装置的计算程序

利用VB6.0编写的程序对炉门提升装置进行计算。包括电机、液压缸(气缸)的选型计算,吊杆(吊板)的强度核算,各种链轮的外形尺寸的计算,并在运算过程中使用了大量的图形和数据库,以直观、方便的模式方便用户进行设计。     

Measuring Mechanical Behavior of Steel During Solidification: Modeling the SSCC Test

The submerged split chill contraction (SSCC) test can measure forces in a solidifying steel shell under controlled conditions that match those of commercial casting processes. A computational model of this test is developed and applied to increase understanding of the thermal-mechanical behavior during the initial solidification of steel. Determining the stress profile is difficult because of the complicated geometry of the experimental apparatus and the nonuniform temperature and strength across the shell. The two-dimensional axisymmetric elastic-viscoplastic finite-element model of the SSCC test features different mechanical properties and constitutive equations for delta-ferrite and austenite that are functions of both the temperature and the strain rate. The model successfully matches measurements of (1) temperature history, (2) shell thickness, (3) solidification force, and (4) failure location. In addition, the model reveals the stress and strain profiles through the shell and explains what the experiment is actually measuring. In addition to the strength of the shell, the measured force is governed by the strength of the junction between the upper and lower test pieces and depends on friction at the shell–cylinder interface. The SSCC test and the validated model together are a powerful analysis tool for mechanical behavior, hot tear crack formation, and other phenomena in solidification processes such as continuous casting.     

气瓶内部淬火过程的流动换热特性

 大直径厚壁气瓶内部淬火时的流动换热过程极其复杂,受到多种因素的影响,而研究气瓶内部压强和温度的变化规律对改善流动换热效果、提高产品组织性能具有重要的理论指导意义。以914 mm厚壁气瓶和瓶内流体为研究对象,建立了二维等效流 固耦合模型;采用多喷嘴系统对气瓶内外进行喷水淬火,研究了气瓶总长、喷水流速及淬火时间对瓶内压强及内壁温度的影响,通过间歇淬火试验验证了数学模型的正确性。结果发现,气瓶长度对瓶内压强和瓶壁温度的影响显著,喷水流速次之,当喷水流速大于8 m/s后,水量对瓶壁的冷却效果大大降低;气瓶内壁长度方向的温度梯度分别随气瓶总长的增加和淬火时间的延长而减小,但基本不受喷水量的影响。