正弦曲线波纹管流动与换热特性研究

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3.0 陈辉 2024-11-19 6 4 6.62MB 124 页 15积分
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I
中文摘要
换热器是热能交换的主要设备,被广泛地应用在石油、化工等工业生产的许
多领域,任何热交换设备均是两种不同温度的流体在非物理接触条件下实现热量
的交换,提高换热器的换热性能对于节能减排,资源高效利用具有重要的意义。
紧凑型换热器由于具有质量轻,性能高的特点已经广泛应用在换热器行业。通过
增强的表面来提高换热器的换热性能已经成功地在制冷,汽车和加工等行业中使
用。迄今为止,在国内外部分专家学者对波纹管换热器进行过研究。然而,对于
一种曲线光滑的正弦波纹管研究甚少,这也为国内在异型管换热领域留下很大的
发展空间,相信不久的将来拥有自主知识产权的波纹管会广泛应用在工业生产的
各个领域。
本文引入正弦弯度参数,提出一种基于正弦曲线生成的波纹管,通过 CFD
术,对管内湍流流动状态下的换热与流动进行数值模拟,分析了流体流动状态和
正弦弯度对管内换热与流动阻力特性的影响,并根据数值计算结果拟合出旺盛湍
流区正弦曲线管管内换热系数的准则关系式,为此,本文的主要研究内容有:
1. 比较研究三种常见波纹管(波节管、缩放管和正弦曲线波纹管)及普通直
管之间在传热强化性能以及流动阻力性能方面的差别,并结合场协同原
理分析,通过实验来验证本文数值计算的精确性。
2. 研究高粘度介质在管内的流动和换热特性,推导出正弦曲线波纹管换热表
面积的计算公式,为车用换热器计算程序的开发做好准备。
3. 分别对气流横掠不同正弦弯度的正弦曲线波纹管的换热及流动特性分别
研究,通过从换热器中提取典型单元作为数值设计的对象,确定正弦曲
线波纹管外换热能力与翅片安装位置之间的变化关系。
4. 采用 VB6.0 程序语言及其提供的 DAO 数据库访问对象,结合换热器性能
预测的 NTU-
ε
方法,完成了管片式正弦曲线管换热器性能预测的可视化
程序的编制。
关键词: 正弦曲线波纹管;正弦弯度;对流换热;流动阻力;场协
同;数值计算;VB 程序
II
ABSTRACT
Heat exchangers are some of the most widely used applications area in industry.
Heat exchangers are devices that allow heat transfer between two fluids that have
different temperatures without physical contact between them. Heat transfer increment
is generally crucial for some reasons, such as saving energy and material resources.
Therefore, compact heat exchangers that have low-weight and high level of
performance, must be designed for the heat-exchanger industry. Enhanced surfaces
have been successfully used in the heat transfer industry to obtain more compact and
efficient units. Heat transfer enhancement technology has been widely used in heat
exchanger in the refrigeration, automotive and process industries among others. The
heat transfer enhancement has been analyzed by various methods in order to have
compact heat exchangers. Heretofore, convective heat transfer of corrugated tube has
been researched by some scholars. However, sinusoidal corrugated tube has been very
little studied at home and abroad.
A new type of corrugated tube based on sine function is proposed by introducing
a parameter of sine camber. The heat transfer and flow around sinusoidal corrugated
tubes with different sine camber e are investigated in this paper. Computational Fluid
Dynamics (CFD) was used to analysis flow state and sine camber of tube influence on
the heat transfer and flow, a correlation equations of Nu (Nusselt) =f(Re) is given, for
these, the research has the following main contents:
1. The theoretical comparative analysis with field synergy principle is carried out
for the heat transfer and flow resistance in corrugated tubes, zoom tube and
sinusoidal tube, and its Experimental Verification
2. The heat transfer and flow characteristic of high viscosity medium in tube is
researched, deducing calculation formula of sinusoidal tubes heat exchange
area, and designing application programmers.
3. Convective heat transfer and flow resistance characteristic around sinusoidal
tubes with different sine camber ein cross flow are investigated. And the
relationship between a heat transfer rate and fin position.
4. Based on “NTU-ε” algorithm, a visualized software is programmed to evaluate
the performance for the finned tube heat exchanger by object oriented
III
programming VB6.0 with ADO object database access. Practical
calculations validate this software.
Keywords Sinusoidal tube; Sine camber; Heat transfer; Flow
resistance; Field synergy; Numerical calculation; VB
programming
IV
目录
中文摘要 ........................................................................................................................I
ABSTRACT ..................................................................................................................II
目录 ............................................................................................................................. IV
第一章 绪论 ................................................................................................................. 1
§1.1 数值传热学的意义 ....................................................................................... 1
§1.2 课题的研究背景及意义 ............................................................................. 2
§1.3 国内外波纹管的发展现状 ......................................................................... 3
§1.4 本文主要研究内容 ........................................................................................ 6
§1.5 本课题难点与创新点 .................................................................................... 7
§1.5.1 本课题难点 ......................................................................................... 7
§1.5.2 本课题创新点 ..................................................................................... 7
第二章 三种常见波纹管内流动与换热特性比较分析 ............................................. 8
§2.1 波纹管强化换热原理 ................................................................................... 8
§2.1.1 边界层理论 ......................................................................................... 8
§2.1.2 波纹管换热器强化换热性能理论分析 .............................................. 9
§2.2 计算流体力学概述 ...................................................................................... 10
§2.2.1 计算流体力学基本原理 ................................................................... 10
§2.2.2 对流项离散格式的构造 .................................................................... 11
§2.2.3 湍流的数值模拟方法 ....................................................................... 13
§2.2.4 流动模型简介 ................................................................................... 15
§2.2.5 粘性流体运动的基本方程及定解条件 ........................................... 15
§2.3 基于 CFD 波纹管内流动与换热的数值模拟 ............................................18
§2.3.1 计算软件简介 ................................................................................... 18
§2.3.2 数值方法 ........................................................................................... 19
§2.4 实验数值验证 ............................................................................................. 27
§2.4.1 实验系统 ........................................................................................... 27
§2.4.2 实验方法 ........................................................................................... 28
§2.4.3 实验结果 ........................................................................................... 28
§2.5 本章小结 ..................................................................................................... 29
V
第三章 正弦曲线波纹管管内流动与换热特性研究 ............................................... 30
§3.1 正弦弯度对正弦曲线管内阻力与换热性能的影响 .................................. 30
§3.1.1 管内低粘度介质对换热与阻力性能的影响 ................................... 30
§3.1.2 管内高粘度介质对换热与阻力性能的影响 ................................... 32
§3.1.3 两种流体管内流动综合性能比 ....................................................... 34
§3.2 正弦曲线管内换热特性准则关联式 ......................................................... 36
§3.2.1 湍流流动准则关系式 ....................................................................... 36
§3.2.2 层流流动准则关系式 ....................................................................... 37
§3.3 正弦曲线换热管换热面积计算 ................................................................. 38
§3.3.1 正弦曲线管的结构尺寸 ................................................................... 39
§3.3.2 换热表面积计算 ............................................................................... 39
§3.3.3 换热表面积公式简化 ....................................................................... 40
§3.4 本章小结 ..................................................................................................... 41
第四章 流体横掠正弦曲线管流动与传热性能分析 ............................................... 43
§4.1 管片式正弦曲线波纹管结构参数对换热性能的影响分析 ..................... 43
§4.1.1 几何模型 ........................................................................................... 43
§4.1.2 边界条件 ........................................................................................... 44
§4.1.3 网格研究 ........................................................................................... 44
§4.1.4 湍流模型 ........................................................................................... 46
§4.1.5 正弦弯度对管外换热性能影响 ....................................................... 47
§4.2 翅片安装位置对换热特性比较分析 ......................................................... 53
§4.2.1 几何模型 ........................................................................................... 53
§4.2.2 数值方法 ........................................................................................... 54
§4.2.3 计算结果分析 ................................................................................... 55
§4.3 数值方法在管片式正弦曲线管换热器设计中的应用 ............................. 59
§4.3.1 几何模型 ........................................................................................... 60
§4.3.2 数值方法 ........................................................................................... 61
§4.3.3 流场温度与压力分布 ....................................................................... 62
§4.3.4 翅片 j因子和 f因子随雷诺数变化曲线 ......................................... 68
§4.4 本章小结 ..................................................................................................... 69
第五章 车用紧凑式正弦曲线管换热器计算程序开发 ........................................... 71
§5.1 VB6.0 的数据库管理技术理论 ...................................................................71
VI
§5.1.1 VB6.0 对数据库访问的三种形式 .....................................................71
§5.1.2 数据库的建立与维护 ....................................................................... 72
§5.1.3 使用 DAO 方式访问数据库 ..............................................................73
§5.2 汽车换热器计算程序的数学模型 ............................................................. 74
§5.2.1 计算参数 ........................................................................................... 74
§5.2.2 汽车散热器程序计算步骤 ................................................................ 77
§5.3 基于关系型数据库的汽车换热器软件系统 ............................................. 77
§5.3.1 关系型数据库 ................................................................................... 77
§5.3.2 计算软件系统 ................................................................................... 79
§5.3.3 数据查询与处理系统 ....................................................................... 80
§5.3.4 热流特性动态演示 ........................................................................... 81
§5.3.5 计算软件正确性验证 ....................................................................... 82
§5.4 汽车换热器计算软件界面 ......................................................................... 83
§5.4.1 封面窗体 ............................................................................................ 83
§5.4.2 添加表面窗体 .................................................................................... 84
§5.4.3 Re-J 窗体 ............................................................................................85
§5.4.4 表面参数窗体 .................................................................................... 85
§5.4.5 芯子尺寸窗体 .................................................................................... 86
§5.4.6 计算结果窗体 .................................................................................... 86
§5.5 本章小结 ..................................................................................................... 87
主要符号表 ................................................................................................................. 89
参考文献 ..................................................................................................................... 91
附录 1椭圆积分新法则在椭圆周长计算中正确性验证 ......................................... 96
附录 2 VB 程序源代码 ............................................................................................98
在读期间公开发表的论文及取得成果 ................................................................... 119
致谢 ........................................................................................................................... 121
摘要:

I中文摘要换热器是热能交换的主要设备,被广泛地应用在石油、化工等工业生产的许多领域,任何热交换设备均是两种不同温度的流体在非物理接触条件下实现热量的交换,提高换热器的换热性能对于节能减排,资源高效利用具有重要的意义。紧凑型换热器由于具有质量轻,性能高的特点已经广泛应用在换热器行业。通过增强的表面来提高换热器的换热性能已经成功地在制冷,汽车和加工等行业中使用。迄今为止,在国内外部分专家学者对波纹管换热器进行过研究。然而,对于一种曲线光滑的正弦波纹管研究甚少,这也为国内在异型管换热领域留下很大的发展空间,相信不久的将来拥有自主知识产权的波纹管会广泛应用在工业生产的各个领域。本文引入正弦弯度参数,提...

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作者:陈辉 分类:高等教育资料 价格:15积分 属性:124 页 大小:6.62MB 格式:PDF 时间:2024-11-19

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