用于制冷系统仿真的冷凝器数学模型研究

本文用动态、分布参数方法建立了用于制冷系统仿真的冷凝器数学模型。根据内藏式与外置式冷凝器传热特性的不同,按照系统仿真对于冷凝器数学模型的要求,探讨了模型的求解方法。通过模型运用于系统仿真所得计算值和试验值的比较,验证了该数学模型的正确性。     

PQF连轧钢管温度场数值模拟

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为优化连轧钢管生产工艺、提高荒管产品质量、降低轧制设备能耗,对PQF连轧过程传热机理进行分析,采用有限差分法建立传热数学模型,求解连轧钢管温度场分布情况。该模型能处理轧制过程中复杂的变形场以及各种热力学边界条件,反映钢管在连轧过程中的温度变化规律。仿真结果与现场实测数据吻合良好。     

汽车线束预装配线平衡问题的优化和仿真

为了对复杂的汽车电子线束预装配工艺进行优化与仿真,分析汽车线束的生产工艺特点和要求,以满足生产节拍的工作站数量最小化为优化目标,构建汽车线束预装配工艺平衡问题数学模型,并设计遗传算法实现模型求解。以某汽车线束公司装配线为例,对其预装工艺进行数学描述,并利用Plant Simulation软件进行优化与仿真。结果表明,所提方法和数学模型可为汽车线束装配工艺平衡问题的优化仿真提供可行的解决方案。     

基于耦合传热的涡轮增压器涡轮箱有限元分析

基于涡轮增压器涡轮箱传热机理,采用专业CFD软件和FEM软件分别建立了涡轮箱流体区域和固体区域网格仿真模型。在流体域建立多重旋转坐标系,精确计算出涡轮箱流场、壁面传热系数及温度。应用流固耦合的仿真方法对涡轮箱进行耦合传热分析,得到涡轮箱固体域的温度场并对其进行热应力分析。与实验结果对比发现,仿真模型的温度场符合实际涡轮箱温度分布,最大误差仅为3.3%。该涡轮箱耦合传热模型具有较高的精度,为涡轮增压器的设计优化提供了依据。     

碳碳复合材料快速沉积炉温度场仿真分析

为研究某重点开发产品C/C复合材料气相沉积炉(Chemical Vapor Infiltration)炉内温度分布情况,以及温度梯度对沉积工艺的影响情况,针对沉积炉温度场建立传热数学模型,并对该数学模型进行系统仿真分析。通过有限元软件ABAQUS,模拟计算沉积过程中沉积炉腔室热流量、温度分布情况。研究结果表明:加热器与支撑筒表面温度一致性较好,加热器表面温度误差在±1度范围以内,加热器满足设计要求。     

转筒干燥器中颗粒物料传热过程的数值仿真与实验研究

利用质量平衡方程、能量平衡方程和传热方程,建立了颗粒物料在转筒干燥器干燥过程中的传热数学模型,并使用有限元法进行了仿真研究,该模型能够较好地预测干燥过程中物料颗粒的温度变化,仿真结果与实验结果吻合良好。该仿真程序对此类问题的研究具有参考价值。     

环形加热炉热过程数学模型及其数值仿真系统

在详细分析环形加热炉热工工艺的基础上，建立了管坯加热过程的二维传热过程数学模型，采用有限差分技术中的交替隐式格式（TDMA法）和VB语言，开发出了“环形加热炉管坯加热过程二维传热过程数学模型计算机数值仿真系统”。利用该系统可全面系统地模拟环形加热炉的实际生产过程，准确预测主要热工参数随加热时间的变化规律，为实现计算机优化控制奠定了理论基础。     

板式脉动热管强化传热方法研究

为了研究板式脉动热管的传热性能强化的方法,对原型和改进型两种不同板式脉动热管传热特性进行数值分析比较。基于VOF方法建立板式脉动热管汽液两相流动及相变传热三维非稳态数学模型,仿真得到不同加热功率条件下热管内流型演化和温度分布。仿真结果表明,改进型脉动热管在高功率阶段,整体等效热阻小于原型。     

流固耦合在涡轮叶片瞬态传热仿真中的应用

为真实模拟超高速转子的工作性能,必须对涡轮叶片进行流体-热-结构耦合分析。将有限元软件中提供的流固耦合仿真技术应用到涡轮叶片瞬态传热计算中,利用ANSYS CFX建立了涡轮叶片与高温燃气的流固耦合传热模型,该模型既包括了固体与固体之间的接触传热,也包括了流体与固体之间的耦合传热。以某涡轮转子为例进行了流-固-热耦合分析仿真计算,获得叶片的瞬态温度场分布和热应力。在此基础上结合整个涡轮叶片的实际工作状况对其模拟结果进行定性分析,验证其分析方法的可行性,为实际涡轮叶片设计优化提供了理论依据,有助于叶片加工工艺方法的改进。     

织机六连杆打纬机构的优化设计与仿真

介绍了六连杆打纬机构的构成及工艺要求,建立了含有8个独立变量的数学模型.并利用Matlab工具箱建立优化模型并求解.最后利用优化后的结果在ADAMS软件中构建六连杆打纬机构的虚拟样机模型,通过仿真得到期望的运动特性.     

TEMPERATURE DISTRIBUTION DURING ELECTRO-DISCHARGE ABRASIVE GRINDING

The objective of this work is to develop a finite element method (FEM) based mathematical model to simulate the hybrid machining process of grinding and electric discharge machining (EDM), named as Electro-discharge abrasive grinding (EDAG), for temperature distribution in the workpiece. Two different finite element codes have been developed to calculate the temperature distribution due to grinding heat source and EDM heat source separately. The transient temperature field within workpiece due to cut-off grinding is determined due to moving rectangular heat source. Gaussian heat distribution of power within a spark has been considered in the calculation of temperature distribution due to EDM. Temperature distribution in the workpiece due to combined process is obtained by using superposition. The simulation shows a sudden rise in temperature at the spark location. The predicted results can be used for calculation of thermal stresses, which play a major role as far as high-quality product requirements are concerned.     

TEMPERATURE DISTRIBUTION DURING ELECTRO-DISCHARGE ABRASIVE GRINDING

The objective of this work is to develop a finite element method (FEM) based mathematical model to simulate the hybrid machining process of grinding and electric discharge machining (EDM), named as Electro-discharge abrasive grinding (EDAG), for temperature distribution in the workpiece. Two different finite element codes have been developed to calculate the temperature distribution due to grinding heat source and EDM heat source separately. The transient temperature field within workpiece due to cut-off grinding is determined due to moving rectangular heat source. Gaussian heat distribution of power within a spark has been considered in the calculation of temperature distribution due to EDM. Temperature distribution in the workpiece due to combined process is obtained by using superposition. The simulation shows a sudden rise in temperature at the spark location. The predicted results can be used for calculation of thermal stresses, which play a major role as far as high-quality product requirements are concerned.     

陶瓷自动成型生产线的一次干燥控制研究

采用窑炉余热对陶瓷泥坯进行一次干燥是一种比较通用的方法,这种方法一般采用人工控制的方式,具有产品质量不稳定的缺点,迫切需要提高产品合格率的途径。根据陶瓷的一次干燥工艺,建立了相关的物理模型,设计了自动控制系统,该控制系统能根据温度、湿度等因素的变化,自动调节工艺参数,克服了人工控制的不足。     

冷态滑参数启动方式下的汽轮机转子热应力分析

以当前广泛应用的汽轮机冷态滑参数启动过程为重点研究工况,建立汽轮机转子的全尺寸有限元分析模型．并采用加载等效质量块的方法对其进行简化;采用工程热力学及传热学知识对汽轮机转子边界蒸汽温度和各部位的对流放热系数进行计算．将其作为边界条件加载到汽轮机转子有限元模型上。通过有限元分析软件ANSYS对转子进行温度场的计算与分析,得到温度分布规律、温差最大时刻及出现的部位;采用热应力间接耦合分析法对转子的应力场进行计算分析,得到其应力分布变化情况、等效应力最大值及出现的时刻和部位。根据分析计算结果对汽轮机在使用时应注意的问题提出了合理化建议。     

变风量运行方式下除湿转轮瞬态响应性能的影响因素研究

建立除湿转轮二维传热传质模型,模型中考虑了基体材料蓄热对传热传质的影响,对模型的可靠性进行了验证,模拟误差均在10%以内,满足精度要求,并对不同影响因素下,变风量运行时转轮的瞬态响应性能进行了模拟分析.结果表明:处理空气进口湿度越大温度越低,再生空气进口温度越大湿度越低,处理空气出口湿度响应变化的差值越大,温度响应变化的差值越大;除湿侧风速突然增大时,出口温湿度的响应时间明显小于风速突然减小时的响应时间.计算表明:变风量运行方式可使系统显热负荷减少20%左右,若附加调节措施,可进一步节省显热负荷13%左右.     

Prediction of heat transfer coefficient of steel bars subjected to Tempcore process using nonlinear modeling

This paper deals with the prediction of heat transfer coefficient of steel bars subjected to Tempcore process. A nonlinear mathematical model, in terms of process variables, is developed using response surface methodology. Three significant control parameters are considered. Central composite design of experiments is structured and conducted using finite element method to formulate the predictive nonlinear model. Statistical analysis and experimental results suggest that the proposed model could be used for predicting heat transfer coefficient with adequate accuracy. The knowledge of heat transfer coefficient makes it possible to predict temperature evolution in the steel rods. As the temperature distribution affects the mechanical properties of steel rods, the proposed methodology can be effectively employed in controlling the quality of products.     

Numerical analysis of a radiant drying oven for web applications

During the manufacture of prepregs (composite material made of resin with fiber reinforcement), for the electronics industry, solvent evaporation and product heating are important aspects of the production process. A mathematical model is presented to describe convective and infra-red radiant heating and solvent evaporation from a web (product being processed before being finished as prepreg) in a solvent removal oven. Differential equations are used to model the mass and energy transfers occurring within the oven. Radiation enclosure theory is employed to describe the infrared heat transfer within the oven and use is made of a solvent evaporation model from the literature. Results of temperature distributions in the heated plate (oven component), the web and the air/solvent mixture; the convective and radiant heat transfer rates to the web, the web solvent concentration and the effects of varying the web velocity, heater temperature, heater size and inlet air temperature are in agreement with theory. The results yielded good agreement with a similar study in the literature. Careful analysis of the results of computer simulations under different conditions, such as presented in this study, can be expected to lead to better design decisions prior to building an infra-red oven for web applications.     

不同填料溶液除湿器热质传递过程的数值模拟

建立了逆流除湿过程的热质交换数学模型,对4种不同填料的除湿过程进行了数值求解,得到除湿器内空气含湿量的分布情况,对模拟与试验结果进行了比较。结果表明规整填料的除湿效果优于散装填料,而鲍尔环的除湿效果优于其他散装填料。