Numerical Simulation of Temperature Field during the Dissolution-Diffusion Bonding Process to Mending Iron Casting Defects

The common finite element method microcomputer software for simulation of the temperature field is developed by authors. It is used for calculating the temperature field duringthe mending process of iron casting defects by means of the dissolution-diffusion bonding technology. The correctness has been proved by testing results. This software has been used to analyse thecaused of hardness rising in heat effecting zone,and also find out the approach for solving the problem.     

密集烤房内温度与气流分布数值模拟研究

提高烤房内温度及气流组织分布的均匀性,不仅可有效提高烟叶烘烤质量,而且可在一定程度上缩短烘烤时间,从而降低烘烤能耗。以密集型标准烤房为模拟研究对象,建立了装烟室内空气流动的k-ε两方程三维紊流模型。利用大型计算流体力学软件Fluent,对密集烤房内温度场及速度场进行了系统地数值模拟。分析了装烟室内温度及气流分布的均匀性,并获得了密集烤房合理的送风量。相关的数值模拟结果可为密集烤房结构、气流组织分布优化及循环风机选型提供参考。     

Computational Simulation on Temperature Field of Slab Continuous Casting Mold

On the core concepts that the distributing of temperature and solidified slab shell in mold are a stable process, a new method to calculate the temperature field in mold has been promoted. Consequently, a coupling model on fluid filed and temperature field in stable state has also been established. The concept of effective heat capacity is introduced to deal with the latent heat source term from phase transformation. During the programming for computation, the dynamic updating method is also applied to simulate the influence of solidification on physical properties. The resolution results of this model are analyzed and compared with the tested thickness of solidified shell from casting broke out slab, which demonstrates the correctness and applicability of this model to the practical continuous casting process. Additionally, the thickness distribution of solidified shell in slab mold are also studied in detail.     

Dealing with Thermal Exchange in Temperature Field Simulation in Low Pressure Die-casting Process

The main effort is to develop numerical simulation software of low pressure die casting on Windows platform in Personal Computer, based on the production of aluminum wheel in Die cast wheel manufacture Co. Ltd.. The heat conduction calculation is the basis of solidification simulation. A 3 dimentional model including the refrigeration medium block is set up based on the study of boundary heat exchange. Various calculation method is analyzed for different types of boundary element. A comprehensive calculation model is set up according to practically manipulable parameters in production.     

Research on the Real -time Simulation of Temperature Field for RCC Gravity Dam

The simulation analysis of temperature field under ideal condition can reflects the rule of true temperature field, but accidental factor during construction process will result in difference of the result. This paper studied the Baise RCC Dam with the distributed optical fiber technology and FEM technology, the numerical results were modified with the testing data and the contrastive curves can be obtained for the testing data,ideal simulation data and real -time simulation data. The results indicate that the modified real - time simulation can reflect the true temperature field ; it may serve as a guide for the temperature control.     

农产品空气能热泵烘房温度场的数值模拟与验证

农产品热泵烘房温度场均匀性是影响农产品干燥品质的重要因素。本文选用5HGR-35型农产品热泵烘房,通过交互式CAD/CAM系统(UG)软件建立热泵烘房3D模型,运用理论分析与计算流体动力学(Computational fluid dynamics,CFD)模拟相结合的方法,研究其内部温度场分布情况,对现有结构烘房的温度场建模模拟,分析模拟结果并对现有结构进行优化。通过模拟得出结论:送风速度越大,烘房内热空气更新越快,换热效果越好。综合温度场分布以及农产品烘干要求,烘房内合理的送风速度为11 m/s左右;在11 m/s风速下,烘房空载时在15 min左右达到设定温度(65℃);小推车设计高度加大300~310 mm烘房内部温度场更均匀;烘房顶部均匀加入3块长×宽×高=2900 mm×20 mm×300 mm的挡板,可以使烘房内部温度场更均匀;小推车与烘房之间及相互之间保持30 mm左右间隙摆放更有利于烘房内部温度场的分布;验证试验中,模拟温度与实测温度吻合性良好。上述结论对烘房的进一步优化设计具有一定的指导意义。     

Application of Object-oriented FEM in Developing Simulation Software System

Based on object-oriented method, the classes of object-oriented finite element are defined. The finite element program of static, dynamic characteristics and stability analyses for spatial frame structures is developed with c++ object_oriented language which is successfully incorporated into a computer simulation system of derricks. The results of static, dynamic characteristics and stability analysis for the derricks of F320-A and JJ250/42-K types, obtained with the developed system, are consistent with those obtained by a commercial software, which illustrates the correctness of object-oriented FEM and the reliability of the simulation software.     

机械式冷藏集装箱内温湿度场的数值模拟及其试验研究

以配置了上送风管的机械式冷藏集装箱为研究对象,采用番茄为试验物料,建立三维k-ε紊流计算模型,结合多孔介质模型及组分输运模型,采用非稳态求解方法,计算装载货物情况下集装箱内部的动态温湿度场;同时对该模型相应点的温湿度变化过程进行试验验证研究。结果表明,果蔬在冷藏集装箱运输过程中,自身的呼吸作用及通过箱壁从外界传入的热量对温度场的影响较大,造成货物内部与靠壁面处的温度较高;由于货物区温度较高,且热湿空气被水分含量较低的冷空气取代,致使在同等水蒸气含量下货物区的相对湿度较周围空气区低。模拟计算结果与试验验证结果能较好地吻合,建立的模拟模型可为果蔬冷藏集装箱内温湿度的监测与控制提供技术依据。     

Study on Temperature Fiele of Cast Iron Compound Roll in Slab Hot Rolling

In this paper,a finite element method coupling thermo-elasticity is used to ana-lyze the temperature field of cast iron compund roll in hot rollin8 slab mill.A technique to deal withthe bou ndary of heat and load in rotation is developed.     

Simulation and Experiment of the Forging Process of Railway Lorry Bomsster

Bomsster is a key load-bearing part of railway lorry bogie.Because of its inherent defects casting-steel bomsster could not meet the demands of the heavy load,acceleration and security for lorry.So forging process is proposed to form it.The forming performance of forging-steel bomsster is analyzed.A forging technology is presented which realizes two forging-steel bomsster parts formed in one die.With the plastic forming simulation software DEFORM-3D,the simulation and optimization of the forming process of forging bomsster has been taken based on 3D rigid visco-plastic FEM theory.Optimized scheme has been used to direct the pilot product.The results of product's testing and application suggest that the new forging technology is feasible and the performance of the product is credibility and stabilization.The factory has realized large scale production of a series of forging-steel bomsster.Remarkable benefits of both economy and society have been achieved.     

Numerical Simulation of Flow field and Temperature field in Combustion Chamber Widened Suddenly

The flowfield and temperature field are numerically Simulated by the mathematical model of the fluid flow and heat transfer in circular combustion chamber widened suddenly. The distributions and influence factors of the flow field and temperature field are studied in it. The results have the guiding significance for the design of combustion chamber. The mathematical models can serve as the quantitative analysis methods for design.     

Analysis of Numerical Simulation of Seepage Failure and Seepage Feature of Seawall

In order to analyze seepage feature and seepage failure mechanisms of seawall under flood infiltration, a numerical model for saturated-unsaturated and unsteady seepage flow analysis considering soil permeability variation with seepage failure process was established. And the corresponding finite element computation program was made. Numerical simulation of flood seepage for typical section of real seawall was carried out by use of the program. The computed results were compared with the measured results of field test, which shows good agreement. Based on the numerical simulation results, it can be seen that flood seepage of seawall is a saturated-unsaturated and unsteady seepage flow process and seepage failure of seawall is caused by long time flood infiltration under large seepage gradient. Therefore, upon the flood infiltration, seepage failure of the seawall is a very complicated process, which involves soil permeability variation with seepage failure process and saturated-unsaturated/unsteady seepage flow. It is questionable to use the steady seepage analysis method to simulate seepage failure process of seawall.     

酥饼烤制温度的控制模型及仿真分析

金华酥饼有着千年历史,以传统的烤炉制作为主。基于现阶段酥饼生产中"烤"无法用现代技术替代,如果能将传统炉的温度控制复制到现代炉,将解决酥饼烤制的关键问题。通过对传统炉烤过程中的空气温度和炉壁温度的实测,建立烤制温度模型,利用PID控制方法,用MATLAB工具,在SIMULINK环境下进行仿真试验,经过计算和调整温度传递函数参数,得到适用于电烤温度控制的仿真曲线,为酥饼烤制的实质性研究提供条件。     

Numerical analysis of material surface thaw depth under pulsed electron beam irradiation

We developed a finite element method model. An equality heat source was used to thaw metal with an electron beam in numerical analysis. The temperature field was obtained after the metal thawed with electron beam by numerical analysis. The influence of the material thaw depth was analyzed at differing voltages, energy densities, and energy evenness. A thaw depth diagram was obtained where energy evenness is from 0.9 to 1.0, energy density is from 2 J/cm2 to 17 J/cm2, and voltage is from 25 kV to 50 kV. The change rule of material thaw depth was derived which provides a theoretical reference for fine mould machining with electron beams.     

Deflection and Stress Analysis of a Pavement Slab under Temperature Gradient and Axial Loading Coupling

It has been established that a pavement slab will curl up if a temperature gradient exists across the depth of a slab. A negative temperature gradient causes the slab edge to curl up while a positive temperature gradient curls up the slab center. Temperature stress in slabs is induced by self-weight and other slab constraints. At present in P. R. China, the total stress considered in cement concrete pavement design includes the load stress plus the temperature stress, and only transverse cracking from bottom to top is considered for concrete pavement. Slab responses under axial loads and temperature gradient coupling are not included. We modeled a single slab with a frictionless interface between the slab and foundation using the finite element method. Slab deflection and stress were calculated under axial loads at different slab positions and negative or positive temperature gradient coupling. The calculated results show that the different conditions of axial loads and temperature gradient coupling will change the maximum tension and cause various types of cracks in a slab.     

Electromagnetic field models and their influences onthe temperature field of large hydro generator

To accurately analyze the loss and heat of large hydro generator,the finite element models of 2D steady state electromagnetic field,moving electromagnetic field and field circuit coupling are established respectively.As an example,the losses of the rotor iron and damper winding of a 36 MW tubular hydro generator are calculated.Furthermore,the influences of 3 different electromagnetic field models on the thermal sources and temperatures are analyzed by 3D finite element calculation of the temperature field.The results are compared with the test data and indicate that the precision of the field circuit coupling model is better.The losses of each damp bar are different and the heat of the damp bar at the lee side is larger than that at the windward with the full load.The maximal temperature of the rotor is located at the damper winding,instead of the field winding.The research is valuable for improving the calculation precision of the rotor losses and temperature field and enhancing the reliability of the hydro generator design and operation.     

果蔬强制通风预冷过程中温度场分布的分析

果蔬预冷是冷链的首要环节之一。以100 t冷库为研究对象,建立了气体区和果蔬区的数学、物理模型,采用k-ε紊流模型和非稳态求解方法,运用计算流体力学软件对果蔬预冷降温过程进行了三维非稳态数值模拟。在其他参数相同的条件下,比较分析了不同风速和送风方式下的温度场分布情况。结果表明：送风速度对库内温度场有显著影响,温度随风速的增大而降低,且温度梯度逐渐减小;对比两种送风方式,上送下回送风方式预冷均匀性较好。     

Numerical Simulation in Flow Field of CNG Vehicle Catalytic Converters

The steady flow in the catalytic converters of CNG was simulated. The gas can breakaway in the entering pipe and the flow of the gas can convergence well in the exhaust pipe. The flow distributing mainly depends on the flow capability of the expanding pipe. The pressure falls apparently in the carrier of catalytic converters. The noble metals in the center of the catalytic converters are consumed more quickly than the edge zone.