【作者】 陈昌；

【导师】 陈立平；

【作者基本信息】 华中科技大学 ， 机械设计及理论， 2013， 博士

【摘要】 热流体系统广泛应用于工业生产和日常生活，深深影响人类活动，历经经验结合实验的方法之后，仿真技术已逐渐成为热流体系统的重要设计手段之一。现行的热流体系统仿真平台存在模型不对用户开放、同一平台模型仅限于设备模型级别的重用、不同平台之间模型难以共享，同时通用仿真平台由于采用显示状态空间描述模型难以保持热流体系统拓扑结构。针对以上热流体系统建模仿真现存的问题，在国家973计划项目、863计划项目以及自然科学基金项目的支撑下，本文基于多领域统一面向对象建模仿真技术，针对基础热流体系统、相变引起能量传递的两相平衡系统以及一维分布参数热流体系统等主题，围绕热流体系统的模型抽象、模型非因果表达、模型重用等关键技术，对热流体系统模型建立方法和模型库框架构建开展了深入研究，主要包括以下几个方面工作。以多领域统一面向对象建模语言Modelica为例，详细分析了面向对象建模仿真的原理及技术特征，结合热流体系统本身的特点，探索了基于面向对象技术的热流体系统分解和层次递进构建方法，继而研究热流体系统模型的非因果表达和重用机制，提出了热流体系统设备模型与工质模型的解耦机制，以上成果提供了热流体系统模型的建立方法和原则。探索了基础热流体模型库的建立方法，并制定了基础热流体模型的框架结构，将模型库分为连接器层、基础物理层、元件抽象层和元件层，详细论述了此四个层次模型的抽象过程和实现，进而构建了基础热流体模型库，涵盖了热流体系统最为常用的基础组件：物理现象模型、传热和流体传输修正方程、管道、泵类、阀类、换热类等。并以车用发动机冷却系统为例，展示基于该模型库的行业专用模型库构建方法和工程价值。研究了精馏系统模型的构建方法，提出了精馏系统设备模型和混合物工质模型的解耦建模和耦合建模机制。针对精馏系统中工质模型预测方法以及混合规则众多、混合物种类繁多的问题，提出了精馏系统结构层次递进的建模方法，建立了完整的精馏工质模型框架，将工质模型分为三个层次：基础层、方法层、实例层，实现了相平衡预测方法跟混合物组分信息、混合规则的分离，可使各层模型得到最大化的重用，非常便于新模型的引入。对精馏系统做了详细的系统分解及论述，建立了精馏系统设备模型并进行了验证工作。针对偏微分方程描述的热流体系统，基于线上算法，研究了偏微分方程系统至微分代数方程组的转换方法，详细探究了转换过程中的几个关键问题：一维空间求解域的离散、离散节点一、二阶导数差分表达、边界条件的处理，实现了由偏微分方程描述和微分代数方程描述的热流体系统的统一建模，以便利用Modelica进行模型描述和求解。并以人体传热模型为例，详细论述了人体的节段划分、传热一维表达和模型的构建过程，并将仿真结果与实验结果作比较分析。结果表明，该方法可有效建立分布参数热流体系统，具有较强的工程实用价值。本文研究的热流体系统建模方法和遵循该方法建立的模型库已在国家973计划、北京机械动力研究所等众多项目中得到应用。更多还原

【Abstract】 Thermal-fluid systems are widely used in industrial production and daily life, andaffect human activities deeply. After the method of experience combining experiment,simulation becomes one of the important design means for thermal-fluid systems gradually.However, the current thermal-fluid system simulators have shortages as follows: model isdescribed as a black box which is not open to the end-user; model in different simulatorscould not be shared with each other; only supporting reuse of knowledge on the unitmodel level. There are also some general simulation platforms, like Matlab/Simulink,could be used to model and simulate the thermal-fluid system. In these tools, the model isusually expressed in procedural form. So the topology of the system gets lost and anyfuture extension and reuse of the model is tedious and error-prone. To solve the problemsmentioned above, the modeling strategy and framework construction of the model libraryare intensively studied based on the unified multi-domain modeling and simulationtechnology, around the following three key points: abstraction of thermal-fluid system,non-causal expression and reuse of model, in the themes of the basic thermal-fluid system,two-phase equilibrium system and one-dimensional distribution parameters thermal-fluidsystem. The main contribution includes the following.Firstly, with the unified multi-domain language Modelica as an example, theprinciple and technical characteristics of unified multi-domain modeling and simulationare analyzed. Combined with the characteristics of thermal-fluid system, systemdecomposition and level progressive construction of thermal-fluid system are exploredbased on the unified multi-domain technology. And then, the non-causal expression andreuse mechanism of thermal-fluid system model are researched. The decouplingmechanism between the device model and the media model is proposed. The aboveresearch provides the modeling method and principle for thermal-fluid system.Secondly, the method of basic thermal-fluid library is explored and the framework ofthe library is constructed. The library is divided into four levels: the connection level,basic physical level, unit abstraction level, and unit level. The abstraction process andimplement of model in each level is discussed. The library covers the basic unit ofthermal-fluid system, such as physical phenomena, the correct equation of heat transferand fluid flowing, pipe, pump, valve, heat exchanger and so. A vehicle engine cooling system is modeled and simulated to reveal the engineering value of the library.Thirdly, the modeling method of distillation system is studied. The decoupling andcoupling mechanism between the distillation system devices and the mixture media modelis presented. Structured level progressive modeling strategy is proposed in order to solvethat there are many phase equilibrium prediction methods, the mixture rules and kind ofmixture. The mixture media model has three levels: base level, method level and caselevel. The prediction methods, components’ information of mixture and the mixing rulesare separated into the three different levels. A new media could be introduced by changingthe component information of mixture and mixing rules. The distillation system model isdecomposing and the unit models of distillation system are modeled. Based on the mediamodels and unit models, a model of air distillation column is constructed and simulated.The results agreed well with that simulated in Aspen Plus.Finally, based on the methods of line, the method transformed the thermal-fluidsystem described by partial differential equation to differential algebraic equations isresearched. The following three key issues are discussed: discreting of one-dimensionalspace solving domain, differential expression of first and second derivative on the nodeand boundary conditions. The unified modeling of thermal-fluid systems described bypartial differential equation and differential algebraic equations is achieved. With the heattransfer model of the human body as an example, body segment dividing, modeldescribing and implement of the model are discussed in detail. The simulation results areagreed well with the experimental results. It is indicated that the transforming method iseffective for modeling the one-dimensional distribution parameters thermal-fluid system.更多还原