多種柱體的附加質(zhì)量的實驗研究
發(fā)布時間：2024-03-22 23:05
科學(xué)界對于附加質(zhì)量的研究已經(jīng)持續(xù)了一百多年,由此提出的一些基礎(chǔ)理論及框架已經(jīng)基本形成并得到發(fā)展。本文將創(chuàng)新性地通過自行設(shè)計的實驗裝置針對一系列關(guān)于垂直柱體管狀結(jié)構(gòu)(圓柱、方柱、平板)在空氣及不同液體(包括水和15號液態(tài)石蠟油)中的自由衰減振動實驗來探究附加質(zhì)量作用與不同柱體形狀、自身旋轉(zhuǎn)角度以及液體特性(密度、粘度)的關(guān)系.這即為本實驗的主要目標。本實驗將會主要以無量綱的附加質(zhì)量系數(shù)Ca作為研究對象。關(guān)于Ca的計算有兩種主要方法,本文中均有提及。其一是通過比較在空氣中和在液體中的振動固有頻率的差異來計算Ca的數(shù)值。該方法計算簡便準確度高,并可以得到Ca與方柱平板等柱體的自身旋轉(zhuǎn)角度的關(guān)系,但理論認為衰減振動自身的固有頻率只可取自于小振幅區(qū)域,而且對于完整的一次振動過程只能計算一個整體的數(shù)值,所以該方法存在一定局限性。其二是通過關(guān)于等效動力方程的推論基于微積分算式來計算Ca,該方法直接采用試驗獲得的瞬時位移及力信號作為計算數(shù)據(jù)來源,可以實現(xiàn)計算每一個完整振動周期的Ca<...
【文章頁數(shù)】：61 頁
【學(xué)位級別】：碩士
【文章目錄】：
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
本文編號：3935081
【文章頁數(shù)】：61 頁
【學(xué)位級別】：碩士
【文章目錄】：
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
本文編號：3935081
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