圆筒形多层砌体非稳态热计算

对圆筒形多层砌体非稳态传热用有限差分法进行了分析,提出圆筒形多层炉墙非稳态传热的界面层温度计算公式、外表面层温度计算公式以及炉墙温度场计算公式。计算结果表明,炉墙外表面温度计算值与实测值误差仅为4.06％。吻合较好,可满足工程要求。     

汽轮机转子温度场和热应力的动态分析

将空心的汽轮机转子简化成长圆筒壁模型,在一定的假设条件下得到了描述其导热特性的微分方程。利用复频域分析方法求解了长圆筒壁的一维动态导热特性,并根据热弹性理论得到了转子温度场和热应力的传递函数。进而对内表面绝热、外表面为阶跃温度输入和内、外表面都为阶跃温度输入的两种情况下转子温度场和热应力的变化进行了计算和分析。计算结果表明,采用对转子内、外表面同时加热或冷却的方法,能够在不增加热应力的条件下,加速转子达到温度平衡状态,有利于缩短汽轮机组的开停机时间,并提高跟踪机组负荷变化的灵活性。     

基于惯性环节的汽轮机转子温度计算方法

介绍了基于一阶惯性环节的高压转子温度场的计算原理和方法,推导了在控制系统中使用的简化迭代计算公式.针对1 000 MW超超临界汽轮机,利用有限元法对其温度场进行了计算,验证了在热应力监控中使用高压内缸内壁温度等效代替高压转子外表面温度的合理性.采用一阶惯性环节法、差分法和有限元法等3种方法,对汽轮机高压转子冷态启动、温态启动、热态启动、极热态启动和滑参数停机过程的体积平均温度和转子中心温度进行了计算,并对比分析了3种方法的转子表面温差和转子中心温差的计算精度.结果表明:一阶惯性环节法的计算精度高且方便易用,可作为一种监控汽轮机转子温度场的有效方法.     

锅炉过热器管壁温度计算方法(草案)制订说明

Ⅰ计算壁温的基本公式(1)根据许多设计同志的意见,现代大型锅炉过热器管的外壁温度很高,特别是再热器管子有可能限制于外壁的氧化速度,因此作为过热器壁温的基本计算公式,除了管子内外壁的算术平均温度t_B 外,还应核算管子外壁温度t_(WB)。     

基于缸内燃烧分析的发动机金属温度场计算方法

为了提高发动机缸盖、缸体金属温度场分析的准确度,提出了一种基于缸内燃烧分析的发动机金属温度场分析方法。首先,基于发动机的标定信息,进行了缸内的燃烧分析,研究了各部分边界上的对流传热量;其次,进行了水套的流动分析,对其传热系数进行了评估;再次,考虑了活塞环与缸壁的摩擦换热及活塞与缸壁的热传导;最后,基于上述的热边界条件进行了金属温度场的计算,并与试验进行了验证。结果表明:采用该算法,缸盖、缸体金属温度场分布比较合理,监测点温度与试验比较吻合。     

缸套瞬态温度场的有限元分析

本文提供了计算二维温度场的通用方法,即瞬态温度场的非线性有限元解法.首先,以实测的温度确定缸壁与燃气的接触边界条件,计算出稳定温度场.以稳定温度场做初始条件,考虑活塞运动情况,利用所确定的放热系数确定缸套与燃气的接触边界条件计算了铸铁缸套的瞬态温度场,给出了缸套表面层的温度波动情况.     

不同壁厚对气缸套壁面温度影响的有限元分析

以某重型柴油机的薄壁顶置湿式气缸套为研究对象,结合特定热边界条件,对气缸套的稳态温度场进行了有限元分析,气缸套三维温度场的计算结果显示气缸套最高温度为239℃,出现在气缸套活塞上止点附近。通过对比不同气缸套壁厚对壁面温度场的影响,明确了气缸套的变形分析中不同壁厚对气缸套壁面温度的影响,为气缸套结构设计改进提供理论指导和依据。     

膜式水冷壁特定点温度相关性的研究

为了监测电站锅炉膜式水冷壁向火侧危险点壁温,基于温度场数值模拟结果研究了向火侧危险点温度和背火侧特定点温度的关系。首先用数值模拟方法计算了大量工况下水冷壁截面温度场分布,然后根据数值模拟结果拟合背火侧3个特征点温度差值与向火侧2个危险点温度的关系表达式,并进行了实验验证。通过监测水冷壁背火侧3个特征点温度,根据关系式即可实现在线间接监测向火侧危险点温度。图3表3参8     

加热管中的壁温和流动湿蒸汽温度场分析

建立了一维数学模型对加热管内流动湿蒸汽时的管壁温度场进行了研究,分别计算出在均匀壁面热流密度这壁的温度场、恒定壁面温度条件下管壁的热流密度场以及汽相温度沿管长方向的变化,得到了不同条件下水滴的汽化长度,并进行也实验验证,计算结果与数据相符,为工程中加热饱和湿蒸汽的设计提供了可靠的依据。     

渡槽在折线温差分布下的横向温度应力计算

为分析渡槽在折线温差分布下的横向温度应力,运用公路桥梁规范中折线温差分布函数,推导了渡槽在折线温差分布下横向温度自约束应力和框架约束应力计算公式,计算了渡槽在冬季骤然降温作用下的温度应力。计算表明,渡槽外表面总应力是壁厚和温差的函数,当壁厚不变,温差减小50%时,其温度应力也相应减小50%,当温差不变,壁厚减小50%时,其温度应力减小21%;与指数温差分布函数计算的温度应力值相比,该方法计算值较小,在设计时若按此考虑渡槽温度荷载,则能显著提高渡槽的安全性能。     

Pressure drop and heat transferin spanwise-periodic fluted channels

We have conducted numerical studies on the three-dimensional laminar forced convection heat transfer in a channel with spanwise-periodic fluted parts by applying the spectral element and finite difference methods. The flow field is assumed to be fully developed, while the temperature field is supposed to be developing under the fully developed velocity profile. The temperature on the plate surface is kept constant. Pressure drop, heat transfer, and correlation between them are investigated for varying configurations of the fluted channel. The nondimensional formulas with regard to the pressure drop and Nusselt number are derived for the parameters of the channel configurations. Channel efficiency, which is defined as the ratio of the heat transfer enhancement to the increase of pressure drop compared with the parallel plate channel, is studied according to the nondimensional formulas to clarify the optimum parameter range of channel configurations.     

高炉冷却板传热过程数学模型的研究

给出了高炉冷却板和炉衬温度分布的二维稳态传热模型，并分析了冷却板和炉衬的不同结构参数及其物性参数对温度分布和热流密度的影响，为高炉冷却系统的优化设计和控制提供了坚实的理论依据。     

Temperature distribution on inclined plate caused by interaction with supersonic jet

IntroductionThe phenomena of the impingement of a supersonicjet on a solid obstacle is very interesting and importantin relation to the aeronautical and other industrialengineerings[']-l']. A large number of papers hadconcerned with the impingement on a perpendicularplate and evidenced the flow phenomena and thepressure distribuhon on a plate and so on. However, theinvestigation of the impingement on an inclined platecan only be found in merely several papers['-']. Ih thesestudies, it is menti…     

MHD mixed convection from a vertical plate embedded in a porous medium with a convective boundary condition

A numerical approach has been used to study the heat and mass transfer from a vertical plate embedded in a porous medium experiencing a first-order chemical reaction and exposed to a transverse magnetic field. Instead of the commonly used conditions of constant surface temperature or constant heat flux, a convective boundary condition is employed which makes this study unique and the results more realistic and practically useful. The momentum, energy, and concentration equations derived as coupled second-order, ordinary differential equations are solved numerically using a highly accurate and thoroughly tested finite difference algorithm. The effects of Biot number, thermal Grashof number, mass transfer Grashof number, permeability parameter, Hartmann number, Eckert number, Sherwood number and Schmidt number on the velocity, temperature, and concentration profiles are illustrated graphically. A table containing the numerical data for the plate surface temperature, the wall shear stress, and the local Nusselt and Sherwood numbers is also provided. The discussion focuses on the physical interpretation of the results as well their comparison with the results of previous studies.     

Heat transfer analysis of blast furnace stave

The three-dimensional mathematical model of temperature and thermal stress field of the blast furnace stave is built. The radiation heat transmitted from solid materials (coke and ore) to inner surface of the stave, which has been neglected by other studies, is taken into account. The cast steel stave is studied and the finite element method is used to perform the computational analysis with soft ANSYS. Numerical calculations show very good agreement with the results of experiment. Heat transfer analysis is made of the effect of the cooling water velocity and temperature, the cooling channel inter-distance and diameter, the lining material, the cooling water scale, the coating layer on the external surface of the cooling water pipe as well as the gas clearance on the maximum temperature and thermal stress of the stave hot surface. It is found that reducing the water temperature and increasing the water velocity would be uneconomical. The heat transfer and hence the maximum temperature and thermal stress in the stave can be controlled by properly adjusting operating conditions of the blast furnace, such as the gas flow, cooling channel inter-distance and diameter, lining material, coating layer and gas clearance.     

Numerical exploration of thermal radiation and Biot number effects on the flow of a non‐Newtonian MHD Williamson fluid over a vertical convective surface

A theoretical and computational study of the magnetohydrodynamic flow and free convection heat transfer in an electroconductive polymer on the external surface of a vertical plate under radial magnetic field is presented. The Biot number effects are considered at the vertical plate surface via modified boundary conditions. The Williamson viscoelastic model is employed which is representative of certain industrial polymers. The nondimensional, transformed boundary layer equations for momentum and energy are solved with the second‐order accurate implicit Keller box finite difference method under appropriate boundary conditions. Validation of the numerical solutions is achieved via benchmarking with earlier published results. The influence of Weissenberg number (ratio of the relaxation time of the fluid and time scale of the flow), magnetic body force parameter, stream‐wise variable, and Prandtl number on thermo fluid characteristics are studied graphically and via tables. A weak elevation in temperature accompanies increasing Weissenberg number, whereas a significant acceleration in the flow is computed near the vertical plate surface with increasing Weissenberg number. Nusselt number is reduced with increasing Weissenberg number. Skin friction and Nusselt number are both reduced with increasing magnetic field effect. The model is relevant to the simulation of magnetic polymer materials processing.     

红外加热元件辐照度不均匀性的估算

用辐射换热理论计算了长带状、管状、板状加热元件及由以上几种元件组成的组合件,在平行于加热元件的平面上的辐照度不均匀性。提出一个参数——辐照度不均匀系数φ来表示辐照度的不均匀性,φ=E_x/E_0,Ex为x处的辐照度,E_0为参照的辐照度基准。φ主要和几何特性有关,可藉助角系数的概念计算出来。文中给出了上述几种元件φ的计算公式,及某些情况下的工程计算图表。     

MULTIPLE ENGAGEMENT WET CLUTCH HEAT TRANSFER MODEL

To optimize the thermal performance of transmission wet clutches during multiple engagements, a general thermal numerical model has been developed. At every cycle, temperatures are computed throughout the clutch materials until a periodic steady state is achieved. One cycle is characterized by (a) an engagement period where the separator plate is contacting the friction lining with heat being generated while some cooling is provided by the oil passing through friction material grooves; (b) a locked stage of separator plate and friction lining contact during which the heat generation is zero while oil cooling through the grooves continues; and (c) a cooling period with the separator plate completely disengaged from the friction lining while the oil cools both surfaces. Temperatures are calculated from the transient numerical solution of the heat conduction equation in two dimensions. The finite difference technique based on an implicit numerical scheme is employed. This approach is verified by comparison with a known solution as well as experimental data, and a sample run is presented for conditions representative of an actual clutch assembly.     

基于流固耦合的高压混凝土隧洞衬砌结构配筋研究及应用

当采用面力理论计算新疆阿尔塔什水利枢纽工程的发电引水隧洞的配筋量时,衬砌含筋量巨大,与实际情况不符合。对此,采用岩体弹塑性渗流—应力—损伤耦合模型,将动态变化的体积力施加于整个模型,得出混凝土衬砌应变情况,根据衬砌应力按照现行规范进行限裂配筋。计算得出了围岩、衬砌的渗流场、应力场和相应的水力梯度以及最高外渗水头。结果表明,考虑流固耦合下的高压隧洞衬砌应力小于面力理论计算的成果,且前者计算出的混凝土衬砌配筋量远小于后者的计算结果。研究成果可为类似隧洞设计提供参考。