车载变压器散热器空气侧传热和流动特性的数值研究-动力工程专业毕业论文.docx

车载变压器散热器空气侧传热和流动特性
的数值研究
摘要
我国铁路运输事业随着综合国力的增强快速发展,特别是近 10 年来,电力机车保有量和铁路电气化运营里程逐年上升,这就对冷却电力机车主变压器的散热器提出更高的要求。从上世纪 90 年代初,设计先进、结构紧凑、性能优良、可靠性高的铝质板翅式散热器开始应用于新型电力机车。
波纹翅片作为板翅式散热器一种扩展强化传热表面,加工工艺简单、传热性能高,在各种紧凑板翅式散热器上获得广泛应用。车载变压器散热器空气侧采用波纹翅片结构极大的提高了空气中污物颗粒的通过能力,降低了污物颗粒沉积粘附在散热器翅片上的可能性,解决了散热器易污脏、清洗间隔周期短、维护工作量大等问题。对波纹翅片的热力性能进行研究,不仅有利于提高车载变压器散热器系统的整体性能,而且对改进板翅式散热器的结构设计,推出更高效节能的散热器有重要的指导意义。
本文采用不同的湍流模型分别对不同雷诺数 Re 下波纹翅片的传热特性和阻力特性进行了数值研究,并与 Kays 和 London 经典试验数据进行对比,证明了 CFD 数值模拟技术用于研究波纹翅片传热和流动特性方面的可行性。
通过改变波纹翅片的基本几何参数波幅、波长、间距、高度、厚度、圆角半径等,得到了雷诺数 Re 与传热因子 j 和阻力因子 f 的关系曲线以及雷诺数 Re 与综合传热因子 j/f 的关系曲线,通过对波纹通道内温度场和速度场的变化分析了改变翅片基本几何尺寸对散热器传热和阻力性能的影响,同时运用场协同原理深入分析了波纹翅片的传热机理,为优化波纹翅片结构,提高翅片换热性能提供理论指导和技术支持。
关键词:变压器散热器,波纹翅片,数值模拟,传热因子,阻力因子
NUMERICAL STUDY ON AIR SIDE HEAT TRANSFER AND FLOW CHARACTERISTICS OF HEAT EXCHANGER USED ON ELECTRIC OTIVE TRANSFORMER
ABSTRACT
With the enhancement of prehensive national strengthen, railway transport in China gets rapid development. Especially in the recent 10 years, the quantities of electric otive and the mileage of railway transport is rising year by year, which put forward higher requirement of the heat exchangers used for cooling the electric otive main transformers. Since 1990s, the aluminum plate-fin heat exchangers have begun to use in new type electric otive, with its advanced design, compact structure, good performance and high reliability.
Wavy fin as a kind of expansion strengthening heat transfer surface of plate-fin heat exchangers, has won wide application with the advantages of simple processing t echnology, high heat transfer performance. Using wavy fin structure on the air side of transformer heat exchangers can greatly increase the passing of air dirt particles, reduce the sediment and adhesion on the fins, and solve the problems of easy dirty, short cleaning interval period, big maintenance workload. The research on the thermal performance of wavy fin can not only improve the system performance of transformer heat exchangers, bu