Papers by Keyword: Numerical Calculation

Abstract: Solar radiation is the main source of heat gains during the summer period. The most exposed non-translucent structure of the building is the roof. Material characteristics of roof tiles are able to influence the upper surface temperature and also the thermal performance of the whole roof structure. The aim of this article is comparison of the highest temperatures of roofing tiles reached by a summer day in accordance to their material characteristics. Data obtained from an in-situ measurement are compared with the values obtained by numerical calculation. The temperatures obtained by in-situ measurement are higher than thus earned by numerical calculation.

Abstract: Independent dedicated ventilation system is an advanced air conditioning system developed in last few years. There is little research on the design of the system at present. This paper establishes control equation of flow and temperature field based on the energy transmission theory and simulates heat pipe independent dedicated ventilation system using special flow field numerical simulation software. In pretreatment process of FLUENT, this paper uses unstructured six prisms and parallelepiped grid and encrypts grid which makes the result of calculation is more accurate. The simulation uses residual of 10-5 high precision to calculate, and obtains the residual convergence curve. Curve analysis shows that the calculation is very reliable and stable. In post-treatment process, it uses FLUENT results processing module, obtains the temperature flow pattern of heat exchanger independent dedicated ventilation system. We take one of the root canal for analysis. The result shows that the temperature in both sides of the tube is higher, and the temperature through the tube and close to the wall part is lower. It is coincide with the actual working condition of tube ventilation and heat dissipation outside the pipe. This result proves the accuracy of the numerical simulation and provides the reliable theory basis for the design of heat pipe heat exchanger independent dedicated ventilation system.

Abstract: Diffusion research is important for understanding of many processes based on mass transfer. In many respects, diffusion, determines physical and mechanical characteristics for new materials with fine-dispersed matter and a large number of grain boundaries and phases. Models of diffusion along grain boundaries and their modifications are widely known in literature, but they are not always applicable to nanomaterials due to indistinct determination of some notions. At the present paper the model of diffusion is presented, which considers boundaries and area near boundaries as a phase with special properties. Mass transfer between the volume of a grain and a boundary phase is taken into account. The approximate analytical solution of the problem is formulated. In the general case the problem is solved numerically. Non monotonic distributions of concentrations in volume are obtained.

Abstract: A dynamic analysis code has been expanded from the previous quasi-static code and the effect of inertia term is added. In this paper, the influence of inertia term on the pore water pressure is investigated in detail under a uniform deformation field theoretically and it is found that the distribution of pore water pressure is parabolic if there is inertia term. Then in order to verify the calculation precision of this code, the soil-water coupled numerical calculation is carried out based on the assumption of uniform deformation. Special distributively pore water pressure is applied to each finite element according to its radius to keep the uniformity of deformation. The results show that the maximum of pore water pressure appears at the center of circle and it gradually decreases along the radius, which proves the precision of the dynamic analysis code is very high.

Abstract: The SYS Cam-clay model, which is extended based on the Cam-clay model and the critical state theory, is able to describe the heavily overconsolidated and structure soils. However compared with Cam-clay model with five elasto-plastic parameters there are six additional evolutional parameters in SYS Cam-clay model and the sensitivity analysis of the new added parameters should be carried out. Through the calculation of constitutive response assuming the uniform deformation field, the sensitivities of degradation index of structure, degradation index of overconsolidation ratio and rotational hardening index are investigated respectively. It can be seen that the peak strength and the “rewinding behavior” in the effective stress path are influenced greatly while there is no coupling effect of these parameters mutually. The initial overconsolidation ratio and degree of structure also have an effect on the mechanical behavior and the initial specific volume.

Abstract: Based on the assisted gravity draining steam flooding and the development technology of drive drain compound, using computational fluid dynamics software ANYSY CFX to analyze the impact of the oil reservoir thickness、density of the crude oil 、oil viscosity and oil saturation on the seepage velocity difference. Research shows that: These factors have a significant impact on the flow velocity difference Research results provide reference for seepage study of gravity drive of heavy oil .

Abstract: In order to conduct the numerical simulation of rock and soil slope strengthened by the micro-pile with reinforced bar, FEM strength reduction is combined with the program of FLAC which possesses the function of analyzing tensile and shear failure. The micro-pile is under plastic state due to its mechanic features. Solid element and ideal elastic-plastic constitutive model of Mohr-Coulomb are applied as the rock and soil mass and pile. The calculation model can work out the safety factor of slope, the dynamic changing process of pile deformation and failure, the failure mode of slope after strengthened by micro-pile. Then the structural element of pile is used to simulate piles, which can obtain the bending moment and shear force. The beam element is used to simulate the coupling beam. So the layout principle of inner force before the failure can be calculated.

Abstract: Because the shell of modern rocket is more and more thin and the body length to diameter ratio increase constantly, influence to trajectory caused by elasticity effect cannot be ignored any more. Based on the model of Euler-Bernoulli beam, the dynamic equations of flexible rocket are derived by using of Hamilton principle. The influence of distributing mass and aerodynamic force and the coupling between longitudinal and transversal vibration are considered. Example shows ballistic range and altitude of rocket are influenced by elastic effects observably.

Abstract: Aiming at high voltage electrostatic field of melting electron beam gun system, taking 30 kv 60 kw melting electron beam gun for example, the structure of the electric field and boundary conditions was designed. And the mathematical model of the electric field was established. The method of numerical calculation was used to solve the mathematical model, and Matlab software was used to simulate the equipotential lines of the electric field. The electrolytic cell experiment was used to simulate high voltage electrostatic field distribution of the electron beam system. At the same time compared with the two different results, the reasons and the improved method were analyzed. For research and calculation high voltage electrostatic field of processing equipment such as electron beam welding, melting, etc, offers a more general analysis, design and calculation methods.

Abstract: With the deepening of the degree of oil exploration and development, as well as the rapid growth of world demand for oil, heavy oil reservoir development is becoming increasingly important in the position in oil exploration. For reserves a great deal of ultra heavy oil reservoir at present, conventional thermal recovery technology is difficult to obtain a good development effect. In this study we use computational fluid dynamics software ANYSY CFX to analyze the impact of horizontal and vertical pressure gradient on the seepage velocity difference..