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流量波动条件下流动与换热特性研究

作　者: Boutrab Kamel
导　师: 高璞珍
学　校: 哈尔滨工程大学
专　业: 热能工程
关键词: 数值模拟圆管流量脉动流动特性换热
分类号: TK124
类　型: 硕士论文
年　份: 2011年
下　载: 6次
引　用: 0次
阅　读: 论文下载

内容摘要

本文使用数值计算软件CFD研究了圆管中单相水脉动紊流的流动和传热特性。计算使用了标准k-ε模型,稳定流动状态的模拟结果与经典的勃拉休斯公式、迪图斯-贝尔特公式吻合得很好。将加热和不加热管道内脉动流动数值模拟的结果与实验结果进行了比较。模拟的参数如：平均速度,速度振幅,加热功率和流体温度等均从试验数据中计算得到,并在CFX中作为各种模拟条件。试验与计算的结果对比表明：两种方法对压降的研究有相似之处,并且二者之间存在相位差。计算得到的对流换热系数与试验的对流换热系数符合程度较差,但与迪图斯-贝尔特公式吻合得很好,对这种差异的原因进行了分析。通过数值计算研究了加热功率、脉动周期和振幅改变对流动特性,对流换热系数,努谢尔特数,壁面温度和截面流体温度的影响规律。结果表明：流动特性和换热系数会周期性地波动,波动周期与入口速度的脉动周期相一致。流速脉动周期的变化对摩阻系数和努谢尔特数没有影响,但是速度振幅和平均速度的增加会使摩阻系数和努谢尔特数增加。由于未考虑固体壁面对流体流动的影响,没有观察到加热功率的增加对压降和对流换热系数的影响。

全文目录

摘要  5-6
Abstract  6-10
CHAPTER 1 INTRODUCTION  10-17
  1.1 BACKGROUND  10-11
  1.2 OVERVIEW  11-15
    1.2.1 Theory research  11-12
    1.2.2 Experimental research  12-14
    1.2.3 Numerical research  14-15
  1.3 OBJECTIVES AND SIGNIFICANCE OF RESEARCH  15-16
  1.4 THESIS OUTLINE  16-17
CHAPTER 2:NUMERICAL METHOD AND SOFTWARE DESCRIPTION  17-28
  2.1 COMPUTATIONAL FLUID DYNAMICS INTRODUCTION  17
  2.2 NUMERICAL SOLUTION OF COMPUTATIONAL FLUID DYNAMICS  17-18
  2.3 PROCESS OF COMPUTATIONAL FLUID DYNAMICS  18-20
  2.4 GRID GENERATION  20-21
    2.4.1 Definition  20
    2.4.2 Grid Types  20
    2.4.3 Grid Structure  20-21
  2.5 BOUNDRY CONDITION  21-23
    2.5.1 Generalities  21-22
    2.5.2 Main boundary condition  22-23
  2.6 TURBULENCE  23-27
    2.6.1 Introduction  23-24
    2.6.2 Characteristic of turbulence flow  24
    2.6.3 Reynolds-averaging Equations  24-25
    2.6.4 K-epsilon model  25-27
  2.7 DESCRIPtION OF CFX  27
  2.8 CHAPTER SUMMARY  27-28
CHAPTER 3 CFD MODELING AND VALIDATION  28-38
  3.1 GRID AND BOUNDARY CONDITION  28-30
    3.1.1 Sensitivity analysis  28-29
    3.1.2 Boundary condition and near wall treatment  29-30
  3.2 THEORY  30-32
    3.2.1 Calculate the friction factor  30-32
    3.2.2 Calculation of Nusselt number  32
  3.3 RESULT OF CFD MODEL  32-37
    3.3.1 Calculation of the friction factor  33-35
    3.3.2 Calculation of Nusselt number  35-37
  3.4 CHAPTER SUMMARY  37-38
CHAPTER 4 COMPARISON BETWEEN SIMULATION AND EXPERIMENTAL RESULTS  38-49
  4.1 EXPERIMENTAL FACILITIES  38-40
    4.1.1 The test section  38-39
    4.1.2 Pulsating mechanism  39-40
  4.2 SIMULATION APPROACH  40-41
  4.3 RESULTS AND INTERPRETATIONS  41-48
    4.3.1 Flow fluctuation in non heated pipe  41-42
    4.3.2 Flow fluctuation in heated pipe  42-46
    4.3.3 Discussion  46-48
  4.4 CHAPTER SUMMARY  48-49
CHAPTER 5 SIMULATION RESULTS FOR THE FLOW AND HEAT TRANSFER CHARACTERISTIC  49-63
  5.1 INFLUENCE OF CHANGING PERIOD ON THE FLOW CHARACTERISTICS AND HEAT TRANSFER  49-52
    5.1.1 Influence of changing period on the flow characteristics  49-51
    5.1.2 Influence of changing period on the heat transfer coefficient  51-52
  5.2 INFLUENCE OF CHANGING AMPLITUDE ON THE FLOW CHARACTERISTIC AND HEAT TRANSFER  52-55
    5.2.1 Influence of the variation of the amplitude on the flow characteristics  53-54
    5.2.2 Influence of the variation of the amplitude on the heat transfer  54-55
  5.3 INFLUENCE OF CHANGING THE HEAT POWER ON THE FLOW CHARACTERISTIC  55-57
  5.4 VELOCITY PROFILE  57-59
  5.5 Temperature profile  59-62
  5.6 CHAPTER SUMMARY  62-63
CONCLUSION  63-65
REFERENCES  65-68
ACKNOWLEDGMENT  68

流量波动条件下流动与换热特性研究

内容摘要

全文目录

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