多种柱体的附加质量的实验研究
发布时间：2024-03-22 23:05
科学界对于附加质量的研究已经持续了一百多年,由此提出的一些基础理论及框架已经基本形成并得到发展。本文将创新性地通过自行设计的实验装置针对一系列关于垂直柱体管状结构(圆柱、方柱、平板)在空气及不同液体(包括水和15号液态石蜡油)中的自由衰减振动实验来探究附加质量作用与不同柱体形状、自身旋转角度以及液体特性(密度、粘度)的关系.这即为本实验的主要目标。本实验将会主要以无量纲的附加质量系数Ca作为研究对象。关于Ca的计算有两种主要方法,本文中均有提及。其一是通过比较在空气中和在液体中的振动固有频率的差异来计算Ca的数值。该方法计算简便准确度高,并可以得到Ca与方柱平板等柱体的自身旋转角度的关系,但理论认为衰减振动自身的固有频率只可取自于小振幅区域,而且对于完整的一次振动过程只能计算一个整体的数值,所以该方法存在一定局限性。其二是通过关于等效动力方程的推论基于微积分算式来计算Ca,该方法直接采用试验获得的瞬时位移及力信号作为计算数据来源,可以实现计算每一个完整振动周期的Ca<...
【文章页数】：61 页
【学位级别】：硕士
【文章目录】：
摘要
Abstract
Acknowledgement
Nomenclature
Chapter 1 INTRODUCTION
1.1 Research Background
1.2 Literature review
1.3 Objectives
1.4 Thesis outline
Chapter 2 THEORIES AND METHODOLOGIES
2.1 Basic concepts and phenomenon
2.1.1 Mechanical definition equations
2.1.2 Added mass in potential flow (rectilinear motion)
2.1.3 Decay test
2.2 Calculation methodologies
2.2.1 Calculation via the natural frequency shifts
2.2.2 Calculation via the dynamic equilibrium equation
2.3 Chapter summary
Chapter 3 EXPERIMENTAL SETUP
3.1 Brief introduction of the framework
3.2 Major elements and test fluids
3.2.1 Laser vibrometer
3.2.2 Load cell
3.2.3 Air bearings
3.2.4 Test cylinders
3.2.5 Test fluids
3.2.6 Other accessories
3.3 Flow diagram of measurement and system structure
3.4 Chapter summary
Chapter 4 RESULTS AND DISCUSSIONS
4.1 Basic parameters
4.2 Signal processing
4.2.1 Signal transformation from measurement devices
4.2.2 FFT and signal filtering
4.3 Circumstances of motion
4.4 Calculation of Ca via shifts of natural frequencies
4.5 Calculation of Ca via dynamic equilibrium equation
4.5.1 Limitations of frequency shifts
4.5.2 Obtaining the fluid force (Removing the inertia force)
4.5.3 Analysis of experimental phenomenon
4.5.4 Dependence of Ca versus A/D
4.5.5 Dependence of Ca versus fluid properties
4.6 Chapter summary
CONCLUSIONS
REFERENCES
本文编号：3935081
【文章页数】：61 页
【学位级别】：硕士
【文章目录】：
摘要
Abstract
Acknowledgement
Nomenclature
Chapter 1 INTRODUCTION
1.1 Research Background
1.2 Literature review
1.3 Objectives
1.4 Thesis outline
Chapter 2 THEORIES AND METHODOLOGIES
2.1 Basic concepts and phenomenon
2.1.1 Mechanical definition equations
2.1.2 Added mass in potential flow (rectilinear motion)
2.1.3 Decay test
2.2 Calculation methodologies
2.2.1 Calculation via the natural frequency shifts
2.2.2 Calculation via the dynamic equilibrium equation
2.3 Chapter summary
Chapter 3 EXPERIMENTAL SETUP
3.1 Brief introduction of the framework
3.2 Major elements and test fluids
3.2.1 Laser vibrometer
3.2.2 Load cell
3.2.3 Air bearings
3.2.4 Test cylinders
3.2.5 Test fluids
3.2.6 Other accessories
3.3 Flow diagram of measurement and system structure
3.4 Chapter summary
Chapter 4 RESULTS AND DISCUSSIONS
4.1 Basic parameters
4.2 Signal processing
4.2.1 Signal transformation from measurement devices
4.2.2 FFT and signal filtering
4.3 Circumstances of motion
4.4 Calculation of Ca via shifts of natural frequencies
4.5 Calculation of Ca via dynamic equilibrium equation
4.5.1 Limitations of frequency shifts
4.5.2 Obtaining the fluid force (Removing the inertia force)
4.5.3 Analysis of experimental phenomenon
4.5.4 Dependence of Ca versus A/D
4.5.5 Dependence of Ca versus fluid properties
4.6 Chapter summary
CONCLUSIONS
REFERENCES
本文编号：3935081
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