中小型灯泡贯流式水轮发电机热流耦合温度场数值模拟研究

发布时间：2018-04-01 17:25

本文选题：中小型　切入点：灯泡贯流式水轮发电机　出处：《重庆理工大学》2017年硕士论文

【摘要】：开发和利用低水头及超低水头的水力资源,中小型灯泡贯流式水轮发电机组是最佳的机组型式。由于中小型灯泡贯流式水轮发电机组受制于安装空间和结构形式,相较于其它类型的水力发电机,随着单机容量的不断提高,其结构更紧凑,通风散热条件更差,各部件温升更高,严重影响发电机的正常使用寿命和运行的可靠性。因此,在发电机设计、制造过程中,需要准确计算和分析发电机的温度场分布。然而,以往在计算发电机热源损耗及其内部温度时主要依靠传统公式和设计经验,无法准确描述发电机内温度场分布。本研究以某一型号中小型灯泡贯流式水轮发电机为研究对象,利用数值模拟方法,从热源损耗、多物理耦合场和通风散热结构优化的角度对发电机温度场展开了计算和分析。首先,根据发电机基本结构尺寸生成二维几何模型;建立了二维电磁场有限元分析模型并确定了发电机试验工况和额定工况下的励磁参数和边界条件;利用有限元法分别计算了发电机定子原结构和两种改造结构的时均铁耗分布。其次,根据传热学、计算流体动力学以及多物理场耦合理论,建立了发电机热流耦合温度场数值计算三维模型;以电磁场有限元计算得到的定子时均铁耗以及UDF编程得到定转子铜耗为热源,计算了发电机在试验工况下的温度场;结合现场实测数据,验证了所施加边界条件的准确性;对额定工况下发电机的温度场进行了计算分析并讨论了入口冷却风速大小和定子有无轭部通风孔对发电机各部件温升的影响;对发电机定子通风散热结构提出了增设齿部通风槽、增大定子线圈截面、适当减少定子轭部通风孔的优化改进措施并分别进行了数值计算和数据对比分析。最后,基于优化设计理论,运用DOE实验设计方法对发电机定子通风散热结构参数(定子轭部通风孔、定子齿部通风槽的大小、位置共四个参数)进行了优化设计;最终获得了定子通风散热的结构最优参数,进一步降低了定子线圈最高温升。论文通过对发电机热流耦合温度场的研究,旨在利用有限元数值计算方法得到发电机内部的温度场分布,提高研发能力。数值计算结果与实际测量结果的对比数据表明,利用热流耦合数值计算方法得到的发电机定转子温度场具有一定准确性和真实性,能够为实际工程应用提供设计依据。
[Abstract]:For the development and utilization of low and ultra-low water head hydraulic resources, the small and medium-sized bulb tubular turbine generator is the best type of unit. Because the medium and small bulb tubular turbine generator sets are subject to the installation space and structure, Compared with other types of hydraulic generators, with the continuous increase of the single unit capacity, its structure is more compact, the ventilation and heat dissipation conditions are worse, and the temperature rise of the components is higher, which seriously affects the normal service life and the reliability of the generator. In the process of generator design and manufacture, it is necessary to accurately calculate and analyze the temperature field distribution of the generator. However, in the past, the traditional formula and design experience were used to calculate the heat source loss and internal temperature of the generator. The temperature field distribution in the generator can not be accurately described. In this study, a small and medium-sized bulb tubular hydrogenerator is used as the research object, and the loss of heat source is obtained by using numerical simulation method. The temperature field of generator is calculated and analyzed from the angle of multi-physical coupling field and optimization of ventilation heat dissipation structure. Firstly, the two-dimensional geometric model is generated according to the basic structure size of generator. The finite element analysis model of two-dimensional electromagnetic field is established and the excitation parameters and boundary conditions of generator under test and rated conditions are determined. Using finite element method, the time-averaged iron consumption distributions of the original structure of generator stator and the two modified structures are calculated, respectively. Secondly, according to the theory of heat transfer, computational fluid dynamics and multi-physical field coupling, A three-dimensional model for the coupled heat flow temperature field of the generator is established, and the temperature field of the generator under the test condition is calculated by using the finite element calculation of the electromagnetic field and the copper consumption of the stator and rotor obtained by UDF programming. The accuracy of the applied boundary conditions is verified by the field measured data. The temperature field of the generator under rated working conditions is calculated and analyzed, and the influence of inlet cooling wind speed and stator yoke vent on the temperature rise of generator components is discussed. For the ventilation and heat dissipation structure of generator stator, the author puts forward the optimization and improvement measures of adding teeth ventilation slot, increasing stator coil section, appropriately reducing ventilation holes in stator yoke, and carries out numerical calculation and data comparison and analysis respectively. Based on the theory of optimal design, the structural parameters of generator stator ventilation and heat dissipation (stator yoke ventilation hole, stator tooth ventilation slot size and position) are optimized by using DOE experimental design method. Finally, the optimal structural parameters of stator ventilation and heat dissipation are obtained, and the maximum temperature rise of stator coil is further reduced. The purpose of this paper is to obtain the temperature field distribution inside the generator by using finite element numerical method, and to improve the R & D capability. The comparison between the numerical calculation results and the actual measurement results shows that, The temperature field of generator stator and rotor obtained by the coupled heat flow numerical calculation method has certain accuracy and authenticity, which can provide the design basis for practical engineering application.
【学位授予单位】：重庆理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM312

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