基于POLYFLOW的环模制粒机流场模拟分析

对苜蓿环模制粒机工作过程作分析。应用POLYFLOW软件对其挤压区域进行二维等温流动的数值模拟,得出流场的压力、速度、流线、剪切速率和粘度的分布规律,旨在了解挤压过程的基础上为制粒机工况的控制和结构的优化提供参考依据。通过POST-CFD中probe功能捕捉模孔的出模压力,将其与模拟压缩试验测得的苜蓿草粉密度达到产品密度要求时对应的挤出力相比,误差低于3%,表明所采用的模拟方法具有一定的可信度。     

某船用锅炉过热器蒸汽与烟气传热流动数值模拟

对某船用锅炉过热器内部蒸汽与外部烟气的湍流流动、传热进行了整体的三维数值模拟.针对该船用锅炉过热器的结构特点,应用Gambit专业软件对其进行三维几何建模和网格划分.应用Fluent软件进行数值模拟,得出蒸汽流场的静压分布规律、流量分配规律、热负荷分布规律和过热器管壁温度场的分布规律.模拟结果与过热器的实际运行工况符合较好.对船用锅炉过热器的结构设计有重要的参考价值.     

环模成型机产率与能耗建模及影响因素分析

以成型原理和受力分析为基础,推导出适用于各种结构各向异性生物质环模成型机的产能与能耗计算模型,并用实验数据验证模型合理性及通用性。在此基础上,分析各参数对带锥孔模孔的环模成型机性能影响规律。分析结果表明:产率随环模宽度、线速度、开孔率的增大而增加;能耗与物料特性和设备工艺参数有关,在保证物料顺利挤出并稳定成型的前提下,改进模辊材料和加工工艺、选择锥角大且短粗的模孔结构均可降低设备能耗。     

蜂窝陶瓷蓄热体的热应力场数值模拟

对普通正方形格孔蜂窝蓄热体和夹角圆弧过渡正方形格孔蜂窝蓄热体的热应力场进行了数值模拟计算与对比分析.结果表明,夹角圆弧过渡正方形格孔蜂窝蓄热体的低应力区域更大,应力分布也更均匀;数值模拟结果能够指导蓄热体的结构优化设计.     

低温地板辐射采暖传热特性研究

为了揭示低温地板辐射供暖的传热特性,利用Fluent软件和k-ε湍流模型对低温地板辐射采暖系统的温度场进行数值模拟.搭建电热地板辐射采暖实验系统,进行室内温度场的测量和数值模拟,通过实验测试值及模拟值的对比分析,验证数值模拟的正确性.建立低温热水地板辐射采暖物理模型,对不同供水流速和供水温度进行地面温度分布、地板层温度...     

秸秆颗粒成型机吨料电耗影响因素的试验研究

对影响环模秸秆颗粒冷态成型机吨料电耗的主要因素进行了正交试验研究,得出了秸秆粒度、含水率、环模孔长径比三因素与吨料电耗的数学模型,并进行了三因素及两因素间的交互效应分析,通过Matlab软件编程计算,得出吨料电耗最低时的各因素最优组合,即:粒度为6mm,含水率为16%,环模孔长径比为5.2时,吨料电耗为102.33kW·h·t~(-1)。     

发动机气门的动力学及温度场三维数值模拟

采用有限元法对发动机气门进行了动力学及温度场的三维数值模拟，分别得出了气门在动载荷、温度载荷作用下的应力分布规律，研究结果为气门的失效分析和气门的优化设计提供了理论依据。     

燃料反应器中甲烷化学链燃烧的数值模拟

为了更好地了解化学链燃烧过程中气固流动的特点以及反应特性,基于化学动力学理论和颗粒动理学理论,考虑高颗粒浓度下摩擦应力的影响,运用双流体模型,对燃料反应器内化学链燃烧过程进行数值模拟,得到了燃料反应器内流场特性以及温度场分布规律。模拟结果同时得到了反应器内颗粒所形成的内循环流动结构。     

生物质颗粒燃料冷成型技术试验研究

对环模生物质颗粒燃料成型机影响成型的各主要因素进行了分析及试验研究,给出不同生物质原料、粒度、含水率、环模孔长径比等因素与颗粒成型率及吨料电耗的关系,找出生物质颗粒燃料的最佳成型条件。     

基于有限元方法的柴油机锻钢活塞热分析

利用有限元分析软件ANSYS对某款中型柴油机锻钢活塞进行温度场模拟,并对活塞在热载荷下的整体变形、等效应力、环槽变形及销孔变形进行分析。分析结果显示:活塞整体温度场和变形量分布正常;喉口和环槽应力较高;环槽和销孔变形量合理,为柴油机锻钢活塞的研发提供理论参考。     

柴油机孔式喷油嘴内空穴流动的模拟分析

利用混合多相流体模型加空穴模型的方法，模拟了柴油机孔式喷油嘴稳定喷射时嘴内的空穴流动现象，分析了空穴在喷油嘴内形成机理及其分布情况。基于这一模型进一步分析了喷射压力、背压和喷孔长径比、喷孔入口圆角比、非轴对称喷孔等几何结构参数对喷孔内空穴分布的影响。通过模拟计算可知，提高喷射压差和减小喷孔入口圆角半径都可以提高空穴强度，同时也发现提高喷孔长径比可以使空穴在喷孔出口截面上分布更为均匀。从燃油空穴雾化理论的角度出发，空穴强度的提高以及在出口截面上的均匀分布都有利于燃油的破碎雾化。     

Cr-Co-Mo-Ni齿轮钢模锻件晶粒度预测模型研究

模锻件各部位受应力和温度作用的差异性会形成不同的晶粒尺寸。以Cr-Co-Mo-Ni齿轮钢模锻件为对象，结合某锻造厂的实际模锻工艺参数，利用DEFORM软件中的神经网络技术，建立了Cr-Co-Mo-Ni齿轮钢晶粒尺寸和峰值应力的预测模型，并将计算结果与工业试验结果进行了验证对比。结果表明，该模型对于晶粒尺寸的预测最大误差为6.56%，模型精度较高，能够较好地用于模锻过程不同工艺参数下对晶粒尺寸的预测，继而为改善模锻件晶粒尺寸均匀性提供重要的理论基础。     

Thermoelastic Deformation of Three-Layer Combined Die with Non-Uniform Temperature Distribution

During precision forging processes, the elastic and thermal deformations always take place simultaneously on the forging dies, which will affect the dimension accuracy of the final forging components. According to the classic Lamé formulas and thermoelastic mechanics theories, the thermoelastic deformation of a combined die was investigated. Directly related to geometric parameters, material properties, external stresses, and temperature distribution, the expressions of die deformation and contact normal stresses were derived. A three-layer combined die with three different temperature distributions was studied as a specific example. The thermoelastic deformations of each layer, as well as the contact normal stresses between them, were both calculated by the derived expressions and by finite element simulation. There was good agreement between the calculated values and simulated results, which demonstrated the effectiveness and accuracy of the theoretical derivation. Based on this, the total deformation on the inner surface of the combined die and the contact stress between contact layers under non-uniform temperature distribution that would influence the practical die initial design were discussed further.     

共轨管压力波动对喷油率影响的仿真研究

利用仿真软件GT-Suit构建了高压共轨燃油喷射系统的仿真模型,分析了不同长径比下的共轨管内的压力波动规律、平均压力波动规律、喷油压力波动规律,进而分析了对喷油率的影响.通过仿真数据对比,在共轨管长为310 mm、长径比为16时,可使喷油系统的稳定性最优.     

热循环中太阳电池胶接结构中热错配应力的温度分布和调整

分析了太阳电池中石英玻璃盖片／硅橡胶粘结剂／硅晶片胶接试样在热循环（143－403K）下热错配应力的温度分布，发现其只与初始应力状态有关，与循环次数无关，建立了热错温应力调整的概念，分别经113K和77K低温处理后，胶接试样的热错配应力－温度曲线下移，下移幅度与冷处理最低温度有关，与冷处理次数无关，与未处理相比，冷处理胶接试样经热循环后,粘结强度提高。     

Adaptive control of maximum thermal stress in a smart piezocomposite disk

In this paper, an adaptive control problem of the maximum thermal stress in a smart composite disk is analyzed. The disk consists of a transversely isotropic structural layer onto which piezoelectric sensor and actuator layers are bonded. It is considered that an unknown heating temperature distribution acts on the structural layer and a thermally induced voltage distribution is measured on the sensor layer. The unknown heating temperature distribution is inferred from the knowledge of the measured voltage distribution. Applied voltages to electrodes arranged on every actuator layer are determined by optimization so that the maximum thermal stress in the structural layer is minimized and stress constraints imposed on the piezoelectric layers are satisfied. Finally, the suppression ratio of the maximum thermal stress is discussed based on numerical results.     

汽轮机结构元件的损伤和寿命评估

提出了汽轮机转子在高应力疲劳与高温蠕变变互作用下的损伤本构模型与寿命评估方法,以及用于汽轮机转子结构分析的基本方程与变分原理,利用“间置加载”型荷载谱的特点,提出两个基本假设,并根据初始循环应力应变场对损过程中的循环应力应变场进行了有效描述,可对汽轮机转子结构寿命进行评估。     

The numerical solution of gaseous slip flows in microtubes

The gaseous flow in a circular microtube is studied by using of a finite-difference technique. The influences of gas compressibility, rarefaction effect and temperature difference between inlet gas and tube wall on the mass flow rate are comprehensively described. The numerical results indicate that rarefaction effect decreases friction factor and increases mass flow rate due to velocity slip at tube wall. Although inlet Mach number in a microtube is low, gaseous compressibility effect may be significant, because in such a flow problem the length-diameter ratio of tube is usually large so that flow Reynolds number may change much more along the flow path.     

EFFECT OF THE HISTORY OF TEMPERATURE ON THE THERMOELASTOPLASTIC SOLUTION

The stress paths in the transient thermoelastoplastic analysis are strongly dependent upon the history of temperature, whereas stresses in the thermoelastic analysis are determined uniquely by the distribution of temperature.

This paper treats the effect of the history of temperature on the thermoelastoplastic solution of a thick-walled tube. The transient state of stresses in the tube when subjected to inner-surface heating in which the temperature has an exponential time history is discussed in detail, on the assumption that thermal and material properties depend on temperature.     

Control of Thermal Stress in a Piezo-Composite Disk

This article deals with a stress control problem of a composite circular disk consisting of a structural layer onto which piezoceramic layers are bonded. When a heating temperature distribution acts on the bottom free surface, the maximum thermal stress in the structural layer can be controlled by applying electric potentials to electrodes concentrically arranged on each piezoceramic layer. The applied electric potentials are determined by solving an optimization problem so that the maximum thermal stress in the structural layer is minimized subject to constraints on the stresses in the piezoceramic layers. Finally, numerical results are presented.