ANSYS有限元法在测长绝热真空腔二维热分析中的应用

针对测长绝热真空腔内温度场测量困难的特点，提出应用ANSYS有限元仿真与实验研究相结合的方法进行二维热分析。详细介绍了真空腔的ANSYS有限元建模、参数确定、网格划分、施加载荷和求解过程。仿真结果表明外界环境温度变化1℃，绝热真空腔内温度将变化0．085oC。对仿真结果进行了实验验证，实验结果证明利用该仿真技术可准确、可靠地分析绝热真空腔内的温度场，并且提高实验效率的同时降低了实验成本。

复合热释电薄膜红外探测器的二维热分析

根据热释电薄膜红外探测器的结构和测试条件 ,使用有限元软件Ansys对其进行了二维热分析 ,得到了探测器受到红外辐射后的温度场。分析了复合热释电薄膜红外探测器的绝热层对温度场的影响 ,并将它与微桥结构探测器的性能进行了比较。结果表明 ,复合热释电薄膜红外探测器的绝热层能有效地减小热流向硅衬底的散失 ,并且探测器的响应随着绝热层厚度的增大而增大 ;当复合热释电薄膜红外探测器中绝热层的热导率低于空气的热导率时 ,它的绝热性能优于微桥结构。

2D FEM analysis for coupled thermo-hydro-mechanical-migratory processes in near field of hypothetical nuclear waste repository

In order to consider the influence of temperature and underground water movement, an elastoplastic model and a 2D FEM stress fields on the migration of radioactive nuclide with code for analysis of coupled thermo-hydro-mechanical （THM） processes in saturated and unsaturated porous media were extended and improved through introducing the percolation and migration equation, so that the code can be used for solving the temperature field, flow field, stress field and nuclide concentration field simultaneously. The states of temperatures, pore pressures and nuclide concentrations in the near field of a hypothetical nuclear waste repository were investigated. The influence of the half life of the radioactive nuclide on the temporal change of nuclide concentration was analyzed considering the thermo-hydro-mechanical-migratory coupling. The results show that, at the boundary of the vitrified waste, the concentration of radioactive nuclide with a half life of 10 a falls after a period of rising, with the maximum value of 0.182 mol/m3 and the minimum value of 0.181 mol/m^3 at the end of computation. For a half life of 1 000 a, the concentration of radioactive nuclide always increases with the increase of the time during the computation period; and the maximum value is 1.686 mol/m^3 at the end of the computation. Therefore, under the condition of THM coupling, the concentration of radioactive nuclide with a shorter half life will decrease more quickly with water flow; but for the radioactive nuclide with a longer half life, its concentration will keep at a higher level for a longer time in the migration process.

Two-Dimensional Transient Thermal Analysis of a Phase-Change-Material Canister of a Heat-Pipe Receiver under Gravity

High-temperature Phase Change Material (PCM) is used as a thermal storage medium of a heat-pipe receiver in an advanced solar dynamic system.With both void cavity and natural convection considered,thermal performance of the heat-pipe receiver is numerically analyzed under gravity.The results indicate that the PCM contained in the integrated heat pipe performs an averaging function of heat loadings.The thermal performance of the heat-pipe receiver is stable and reliable.When a heating cycle is stable,the temperature fluctuations both on heat-pipe wall and in PCM canister remain less than 13 K throughout a sunlight and eclipse cycle.The utility of PCM is essentially improved.The maximum melting ratio of PCM is 92%.Under gravity,PCM melts more quickly with the effect of natural convection.Natural convection accelerates the process of phase changes.Numerical results are compared with the experimental results concerned.The accuracy of numerical model under gravity is verified.The experiment for the PCM canister on the ground can be well prepared with our numerical simulation.

Analysis of 2D Flow and Heat Transfer Modeling in Fracture of Porous Media

Heat and mass transfer between porous media and fluid is a complex coupling process, which is widely used in various fields of engineering applications, especially for natural and artificial fractures in oil and gas extraction. In this study, a new method is proposed to deal with the flow and heat transfer problem of steady flow in a fracture. The fluid flow in a fracture was described using the same method as Mohais, who considered a fracture as a channel with porous wall, and the perturbation method was used to solve the mathematical model. Unlike previous studies, the shear jump boundary condition proposed by Ochoa-Tapia and Whitaker was used at the interface between the fluid and porous media. The main methods were perturbation analysis and the application of shear jump boundary conditions. The influence of permeability, channel width, shear jump degree and effective dynamic viscosity on the flow and heat transfer in the channel was studied by analysing the analytical solution. The distribution of axial velocity in the channel with the change of the typical parameters and the sensitivity of the heat transfer was obtained.

NEW DESIGN AND ANALYSIS OF FINITE DIFFERENCE DOMAIN DECOMPOSITION ALGORITHM FOR THE TWO-DIMENSIONAL HEAT EQUATION

It is presented in this paper that the new design and its analysis of finite difference domain decomposition algorithms for the two-dimensional heat equation, and the numerical results have shown the stability and accuracy of the algorithms, where SauFyev asymmetric schemes have been used at the interface points. The Algorithm II in this paper has further extended those developed by Dawson and the others, Zhang and Shen.

Heat transfer analysis of bi-viscous ciliary motion fluid

The impulsion system of cilia motion is deliberated by biviscosity fluid model. The problem of two-dimensional motion of biviscosity fluid privileged in a symmetric channel with ciliated walls is considered. The features of ciliary structures are resolute by the supremacy of viscous effects above inertial possessions by the long-wavelength and low Reynolds approximation. Closed-form solutions for the longitudinal pressure gradient, temperature and velocities are obtained. The pressure gradient and volume flow rate for different values of the biviscosity are also premeditated. The flow possessions for the biviscosity fluid resolute as a function of the cilia and metachronal wave velocity.