热毛细对流温度场全息干涉检测研究

本文采用Ｈｅｌｅ－Ｓｈａｗ盒体,在地面上模拟二维热毛细对流,应用全息干涉技术对热毛细对流温度场进行了测试研究,为了获得感兴趣的热毛细对流温度增量分布,文中提出了将背景温度分布条纹与热毛细对流温度增量分布条纹相分离的方法。     

二维相移逻辑云纹法—条纹图全自动处理的一种方法

本文报告的二维相移逻辑云纹法，可对二维全场条纹图，进行全自动处理。这种方法用了经典云纹的概念，运用了相移的思想，用计算机进行逻辑运算，从而获得了全场条纹图上任意点的信息，为后续的运算提供了方便。这种方法可用于若干种条纹图的处理。     

用二维FFT滤波消除ESPI条纹中的散斑颗粒噪声

在 ESPI 条纹中,由于存在散斑颗粒,使得条纹对比度极大地下降.并给进一步的分析造成较大的因难.本文用二维 FFT 方法,并配以多种低通滤波函数,有效地消除了条纹图中的散斑颗粒。该方法对原始条纹图质量无任何要求,适用于各种形状的条纹.     

表面直接氟化改性对有机玻璃弯曲疲劳性能的影响

本文使用表面直接氟化改性来改善有机玻璃的弯曲疲劳性能。测试了改性前后有机玻璃的断裂韧性与弯曲强度,重点研究了不同缺口形式的有机玻璃在改性前后的弯曲疲劳性能变化并分析了疲劳裂纹扩展过程。弯曲疲劳寿命的测定结果表明有机玻璃的疲劳性能在表面直接氟化改性后得到明显改善,表面氟化层的结构约束效应是有机玻璃疲劳寿命提高的主要原因。此外,在疲劳断裂面上观察到规律性的条纹带形貌,疲劳条纹带的形成与裂纹尖端银纹区的产生具有一定的联系。表面直接氟化改性后疲劳条纹带扩展速率的降低也充分证明了有机玻璃疲劳寿命的提高。研究结果证明,表面直接氟化改性修复是一种提高有机玻璃疲劳性能的可行方法,对有机玻璃的工业使用具有指导意义。     

汽油机燃烧室内温度场测量的激光剪切干涉法

采用激光剪切干涉法测量了汽油机燃烧室内的温度场,并分析了剪切干涉法测温的基本原理,推导出利用干涉条纹图求解温度分布的关系式。在一台二冲程火花点火发动机上设置石英窗和信号同步系统,建立了适合高速摄影的激光剪切干涉测量装置。通过改变剪切干涉量,测取发动机燃烧室内干涉条纹图,从而获得缸内燃烧的二维温度场。结果表明,激光剪切干涉法抗振性强,光路简单可靠,可以进行高速摄像,是研究内燃机燃烧过程的有效方法。从温度场可以看出,燃烧过程中缸内大致可分为三个区,即已燃区、未燃区和燃烧区,具有不同的温度分布和温度梯度。燃烧区温度最高,温度梯度大;已燃区温度次之,梯度较小;未燃区温度最低,但梯度较大。     

全息干涉条纹图的计算机自动处理与识别

本文应用数字图象处理与识别技术在IBM-PC/AT微处理计算机图象处理系统上对复杂的全息干涉条纹图进行了自动分析,文中采用二维灰度值检测的方法获取条纹的准峰或谷值二值图形,然后通过细化得到条纹中心,提出了用记忆跟踪算法自动去除毛刺和噪声线段.在用光标进行人机对话标定零级条纹后,可自动识别出其它整数条纹级数.分数级条纹级数可在整数级条纹数据之间进行线性或非线性插值得到.最后给出了全息条纹图分析的实例.     

热力联合作用下不同材料参数圆薄板的大挠度弯曲

采用由Berger方法和伽辽金方法导出的圆板大挠度弯曲的挠度解析解和ANSYS程序，对均布横向力和均匀温升作用下板中心挠度wc随温度升及横向力的变化规律进行了解析和有限元计算，讨论了板材弹性模量和热膨胀系数不同时，板中温度膜力NT和材料参数（弹性模量E，泊松比μ和热膨胀系数σ）的温度相关性对板大挠度弯曲变形的不同影响规律及温升与横向力联合对圆板大挠度弯曲的不同作用机制。     

抽样定理法重建流场的三维温度分布

结合气流场温度较低，只能得到较少干涉条纹的实际情况，提出了采用轴样定理法重建流场的三维温度分布的模型，并考查了该方法的计算机模拟运算结果，对具体的对象，进行了实验，并采用图像处理方法对条纹进行了一系列处理，最后重建了二个截面上的温度分布。     

二维超外差条纹处理技术

本文从超外差式调频接受机的原理出发,提出一个适合于各种灵敏度测量的二维超外差条纹处理方法.与超外差式调频接受机的优点对应,该条纹处理方法有兼顾各种灵敏度,具有统一的中频处理与鉴相模块等优点.与其它采用条纹骨架的处理方法相比较,该方法实际上是直接的位相检测,其鉴相部分运用普通的phase-shift原理,因而具有测量精高度、灵敏度高的优点.此外,该方法也便于用硬件实现.     

文献摘要

量测挠度的全息干涉图的数字化Gilbert,J.A.,Dudderar,T.D.,Mattys,DR.,Chern.J.H.,Digitization of HolograpicInterferograms for Deflection Measurement.Procedings of The SEM Spring Conferenceon Experimental Mechanios.294—301.本文讨论自动采集和分析全息干涉数据所需的载波条纹技术的基本原理.一个监视二维实时立即处理图片的实用方法.收集载波条纹的背景强度以及变形/载波条纹图,一个高分辨率的电视摄象机/电子组件使得所得的二维光强分布数字化和一个用来快速数据换算和整理的计算机.该系统明     

A laser interferometric measurement of the temperature distribution in convective thermal transfer boundary layers

By means of a double mirror interferometry a two-dimensional temperature distribution measurement in convective thermal boundary layers is presented. When the cold air flows along a hot plate model, the interferometric fringe inside the boundary layer will bend. According to the displacement of the fringe and the relation between temperature and index of refraction, a two-dimensional temperature profile is obtained. All is accomplished by optical device with the help of micro-computer without any contact with the flow field. The project supported by the National Natural Science Foundation of China     

Analytische Untersuchung von freier Konvektion und Filmsieden in laminaren Grenzschichten mit temperaturabhÄngigen Stoffwerten

A two-dimensional, stationary boundary layer modell is derived which allows the treatment of free convection and film boiling on vertical plate and horizontal cylinder under complete consideration of temperature dependent thermophysical properties. Some qualities of these boundary layer solutions are discussed by eleminating the influences of geometry. For horizontal cylinders, a correction of heat transfer for small diameters is given.     

Locally similar solutions for hydromagnetic and thermal slip flow boundary layers over a flat plate with variable fluid properties and convective surface boundary condition

This paper presents heat transfer process in a two-dimensional steady hydromagnetic convective flow of an electrically conducting fluid over a flat plate with partial slip at the surface of the boundary subjected to the convective surface heat flux at the boundary. The analysis accounts for both temperature-dependent viscosity and temperature dependent thermal conductivity. The local similarity equations are derived and solved numerically using the Nachtsheim-Swigert iteration procedure. Results for the dimensionless velocity, temperature and ambient Prandtl number within the boundary layer are displayed graphically delineating the effect of various parameters characterizing the flow. The results show that momentum boundary layer thickness significantly depends on the surface convection parameter, Hartmann number and on the sign of the variable viscosity parameter. The results also show that plate surface temperature is higher when there is no slip at the plate compared to its presence. For both slip and no-slip cases surface temperature of the plate can be controlled by controlling the strength of the applied magnetic field. In modelling the thermal boundary layer flow with variable viscosity and variable thermal conductivity, the Prandtl number must be treated as a variable irrespective of flow conditions whether there is slip or no-slip at the boundary to obtain realistic results.     

On moving heat sources

The two-dimensional thermal problem due to relative motion of a medium and a suddenly activated circular heat source is solved for several boundary conditions. The solutions can be interpreted as for a moving heat source in a stationary medium or a medium moving past a stationary heat source. Uniform and non-uniform temperature, and uniform and non-uniform heat flux boundary conditions are considered. The effect of velocity and radial direction on the temperature distribution is examined. Average, steady-state Nusselt numbers are derived. The transient response of a continuous line source is obtained as a limiting case of the prescribed heat flux solution. Received on 24 September 1996     

Temperature distributions in a periodically stratified layer with slant lamination

The paper deals with the two-dimensional stationary temperature distribution in a composite layer. The nonhomogenous body is assumed to be composed of periodically repeated two-layered laminae. The layering is inclined with an arbitrary angle to the boundary planes. The lower and upper boundary planes are assumed to be kept at given temperatures. The considered problem is solved within the framework of the homogenized model with microlocal parameters, where the continuity thermal conditions on interfaces are satisfied.     

Disturbance propagation in two-dimensional boundary layers over a movable surface in the strong interaction regime

The dependence of the eigenvalues characterizing the disturbance propagation in hypersonic boundary layers on the temperature factor and the surface motion velocity is investigated. The eigenvalues are shown to decrease with an increase in the wall enthalpy. The results of the study are important for formulating well-posed problems for the time-dependent two-dimensional boundary layer equations and for developing adequate computational models.     

Transient natural convection in a cavity with heat input and a constant temperature wall on opposite sides

The transient natural convection of a fluid with Prandtl number of order 200 in a two-dimensional square cavity has been numerically studied. One of the vertical walls of the cavity is kept at a constant (ambient) temperature and a constant heat flux is applied on the opposite wall. The other walls are adiabatic. Initially, a boundary layer is formed near the heated wall; subsequently, a large vortical structure is generated, together with an upper intrusion layer. As time progresses, the average temperature in the cavity increases, and a descending boundary layer is formed near the constant temperature wall. During the transition to the steady-state regime, a thermal stratification pattern is formed. The results are compared with the scale analysis presented by Patterson and Imberger (1980).     

Analysis of transient temperature field in coke drums

One of the primary reasons leading to bulging and cracking in a coke drum is the severe temperature gradient due to cyclic temperature variation. Based on the twodimensional heat conduction theory, an analytical solution of the transient temperature field in the coke drum is obtained, which is different from the known FEM results. The length of the coke drum is considered finite. The dynamic boundary conditions caused by fluid uninterrupted rising in oiling and watering stages are simulated with the iteration method. Numerical results show that the present theoretical model can accurately describe basic features of the transient temperature field in the coke drum. Effects of the geometry of the coke drum and the rising velocity of quench water on the axial temperature gradient are also discussed.     

Heat transfer in stagnation-point flow towards a stretching sheet

 Steady two-dimensional stagnation-point flow of an incompressible viscous fluid over a flat deformable sheet is investigated when the sheet is stretched in its own plane with a velocity proportional to the distance from the stagnation-point. It is shown that for a fluid of small kinematic viscosity, a boundary layer is formed when the stretching velocity is less than the free stream velocity and an inverted boundary layer is formed when the stretching velocity exceeds the free stream velocity. Temperature distribution in the boundary layer is found when the surface is held at constant temperature and surface heat flux is determined. Received on 12 July 2000 / Published online: 29 November 2001     

Numerical simulation of the horizontal Bridgman growth. Part I: Two-dimensional flow

We study the generation of periodic velocity and temperature fields in a plane horizontal crucible of molten metal under the action of a horizontal temperature gradient. The geometry and the boundary conditions are similar to those encountered in the Bridgman growth process of semiconductor crystals, although the present paper is limited to two-dimensional flows. We use transient finite difference and finite element algorithms which lead to identical results. We demonstrate the oscillatory mechanism in two different geometries.