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题名	卧式电机开放管道式蒸发冷却转子内流动传热特性分析; 卧式电机开放管道式蒸发冷却转子内流动传热特性分析
作者	1姚涛,电工研究所
学位类别	博士
答辩日期	2008-06-06
授予单位	中国科学院电工研究所
导师	1顾国彪,电工研究所
关键词	卧式电机 汽轮发电机 开放管道式 蒸发冷却 转子 流动传热 horizontal electrical machine turbine-generator open channel evaporative cooling technique rotor flow and heat transfer
其他题名	卧式电机开放管道式蒸发冷却转子内流动传热特性分析
中文摘要	蒸发冷却技术是继空冷、氢冷、水冷之后的一种新型的电机冷却方式。蒸发冷却技术应用于电机冷却具有冷却效果好、安全可靠、结构简单、维护方便等优点，正受到电力部门和电机制造企业越来越多的重视。蒸发冷却技术应用于水轮发电机目前已趋于成熟，在汽轮发电机定子冷却方面也有了一定的研究成果。但是，随着卧式电机对内冷技术的要求不断提高，迫切需要开展蒸发冷却技术在转子冷却方面的基础研究。在这种情况下，深入研究转子蒸发冷却系统内两相流动和传热特性，对于优化卧式电机转子蒸发冷却技术的设计理论和制造技术具有重要的意义。本文介绍了卧式电机转子蒸发冷却的原理和结构，详尽的分析了蒸发冷却技术应用于卧式电机的技术可行性，得出开放管道式转子蒸发冷却技术方案适合应用于卧式电机的结论；同时对卧式电机开放管道式转子蒸发冷却系统内流动传热特性进行深入分析,具体内容如下： 本文在绝对坐标系基本控制方程的基础上，建立了相对坐标系下描述离心力场中冷却介质流动传热的基本控制方程；然后在相似理论的指导下，对控制方程无因次化，得到主要的影响因素和相应的准则参数；最后推导出物理问题一般解的函数形式。通过理论分析，为数值仿真和试验研究奠定了基础，并可以引导进一步的工作。 开放管道式蒸发冷却转子系统内部冷却介质流动的分析和计算，涉及到高离心力和相变这两个关键性的问题，而目前关于高离心力场下的冷却介质两相流流动特性的研究工作开展得很少，几乎没有相关的文献报道。转子开放管道内冷却介质蒸发的冷却效果，将主要取决于开放管道能通过多大的流量，而流量是由流动压头和流动阻力所决定的。本论文通过参考相关实验工作的结论，在一系列假设条件下，进行了初步的理论分析。最终得到了转子开放管道内部冷却介质流速随转速的变化规律，估计了转速对冷却系统的影响。 本文分析了开放管道式转子蒸发冷却系统内冷却介质传热的基本原理，认为转子开放管道式蒸发冷却系统内冷却介质内部的核态沸腾已被完全抑制，冷却介质的相变传热将以蒸发液层的传热方式发生。蒸发液层传热过程分为液层导热过程，界面蒸发过程和蒸汽扩散过程。并在此理论基础上建立了描述蒸发液层传热过程的理论模型。分析揭示了热流密度与壁面、液层厚度以及高离心力的关系和不同条件下的主要热阻。分析可知，减少液层厚度和增加转速都能增强蒸发液层传热效果，并且指出界面蒸发热阻远小于液层导热热阻和扩散热阻，对液层传热影响很小。 本文对处于高离心场作用下的蒸发液层的稳定性特性进行理论分析，研究对象是开放管道式转子冷却结构，将汽—液—固三相的相互作用考虑进去，从而全面的分析蒸发液层的流动传热稳定性。蒸发液层稳定性分析从液层运动和传热的基本方程出发，研究各种作用力的作用效果，简化控制方程及其边界条件，结合蒸汽的流动和传热的基本方程作为蒸发液层汽—液界面的边界条件，最终得出蒸发液层厚度对时间、空间变化的发展方程；这些影响液层流动传热稳定性公式的得出，对于更好的掌握开放管道式转子蒸发冷却系统中各因素对液层流动传热稳定性有现实的指导意义。 根据流体—结构互动理论，本文建立了能够反映汽—液—固三相相互作用的蒸发液层流体—结构耦合模型，为未来的仿真和实验工作提供了理论基础。 本文对汽轮发电机转子绕组开放管道式蒸发冷却技术进行了模拟实验，分析了加热电流密度、冷却介质流量以及模型转速对冷却效果的影响。试验结果表明，开放管道内部介质流动通畅，转子线圈半径方向上的温度分布均匀，温升情况也符合汽轮发电机温升极限的相关国家标准。 Evaporation-cooling technique is a new kind of cooling technology for electrical machine after air cooling, hydrogen cooling and water cooling. Applied to cooling of generator, the evaporative cooling technique is effective, safe, has simple structure and is easy to maintenance, so it has been more and more valued by electric power department and electrical manufacturing by now. The evaporative cooling technique of hydro-generator has been fully-fledged enough to be applied to hydro-generators in the Three Gorges, and there are also certain research results of cooling of turbine-generator stator. With developing demand of internal cooling technique in horizontal, electrical machine, fundamental research of evaporative cooling technique in the area of rotor cooling is urgently needed. Under the condition, it is instructive in analyzing of the flow and heat transfer of evaporative cooling rotor for the design theory and manufacture technology. This paper introduces the theory and structure of evaporative cooling rotor system of horizontal electrical machine; After in detail analyzing the technical feasibility of applying evaporative cooling technique to horizontal electrical machine, a conclusion that open channel evaporative cooling technique for rotor is feasible for horizontal electrical machine is arrived. Meanwhile this article mainly studies the flow and heat transfer characteristics of open channel evaporative cooling technique for rotor in horizontal electrical machine. The flow and heat transfer of coolant in the rotor system is complex physical phenomena. Based on the basic governing equations in the absolute coordinate system, a theoretical analysis of the basic governing equations describing the physical phenomena in the relative coordinate system is carried out. Using similitude dimensionless variables, non-dimensional numbers and governing equations are generated. The results of the theoretical analysis show that the flow and heat transfer of coolant in the rotor system is affected by many factors, such as centrifugal force, geometry of the circuit, and the fluid properties. Flow analysis and computation of coolant in the open channel evaporative cooling rotor concerns two key issues: high centrifugal force and two-phase flow. The research about this subject has not been found by now. Based on some hypotheses and relevant experiment, this article makes primary analysis and draws the law of coolant velocity changing with rotational speed and influence of rotational speed to the cooling system. This paper analyzes the basic principle of the coolant heat transfer in the open channel evaporative cooling rotor and considers that nucleated boiling of the coolant has been totally controlled in the open channel evaporative cooling rotor and heat transfer of the coolant will occur in the way of evaporative liquid layer. The heat transfer of evaporative liquid layer includes liquid layer conduction, evaporation at the liquid-vapor interface, and mass diffusion in the surrounding. Based on the basic principle, a theoretical model was proposed to investigate the effects of surface temperature, the thickness of the liquid layer and the rotation condition on the heat flux, especially identify all thermal resistances. Analysis results indicate the heat flux increases as the liquid layer thickness decreases and velocity increases and he interfacial resistance is estimated to less than conduction resistance and mass diffusion resistance when the liquid layer thickness is thin, that has little influence on the heat transfer of evaporative liquid layer. A physical model describing the heat and mass transfer processes of the evaporating liquid layer is set up and an evolution equation which shows the development regularity of dimensionless layer thickness with time and space is obtained from the liquid-vapor interfacial conditions. The influence of the liquid physical properties, surface, rotation and boundary condition on stability characteristics of liquid layer is discussed. Based the fluid-structure interaction theory, the fluid-structure interaction model for evaporating liquid layer is established in this paper, that can reflect the vapor-fluid-structure interaction and provide the theory foundation for simulation and experiment work. This paper introduces the simulating experiment of open channel evaporative cooling of turbo generator’s rotor windings. The aim of experiment is to get the temperature distribution of rotor winding in the direction of radius and roughly estimates the power of cooling, aiming at offering technical references for the application of evaporative cooling technique in large turbo generator and for exploring new cooling structure. Influence of current density, coolant flow rate and rotation speed on cooling effect is analyzed in the paper. Experiment results indicate that coolant flows smoothly in the open channel, temperature distribution is even in the radius direction of rotor winding and temperature rise conforms to related national standards of turbine-generator.
语种	中文
公开日期	2010-10-18
页码	97
分类号	TM3;TM5
内容类型	学位论文
源URL	[http://ir.iee.ac.cn/handle/311042/6756]
专题	电工研究所_其他部门_其他部门_博士学位论文
推荐引用方式 GB/T 7714	1姚涛,电工研究所. 卧式电机开放管道式蒸发冷却转子内流动传热特性分析, 卧式电机开放管道式蒸发冷却转子内流动传热特性分析[D]. 中国科学院电工研究所. 2008.

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