在工程應(yīng)用中,流致振動(FIV)現(xiàn)象普遍存在,例如核反應(yīng)堆中的石墨棒,電站的冷卻塔,換熱器的換熱管排等,如果在相關(guān)的結(jié)構(gòu)設(shè)計過程中忽略了流致振動的影響,就可能導(dǎo)致工程設(shè)備的損壞,給工業(yè)生產(chǎn)帶來巨大損失。為便于研究FIV的機理,本文以雙圓柱模型為的研究對象,兩圓柱直徑比為0.4,較小直徑的圓柱固定無振動,較大直徑的圓柱只在垂直于來流方向進行自由振動。通過改變兩圓柱相對角度θ以及兩圓柱之間的間隙比L/d(L為兩圓柱中心距離減去大圓柱半徑,d為小圓柱直徑)可以得出不同排列情況下的流致振動特點。本文主要測量來流速度介于1.8 m/s至20 m/s之間時大直徑圓柱的振動情況,主要有以下四種:無振動(0),共振(SV),弛振(G),小振幅振動(SV)。根據(jù)振動情況的不同把整個研究區(qū)域進行劃分,然后在每個區(qū)域選取幾個具有代表性的點,測量其大直徑圓柱表面的壓力分布以及兩圓柱之間和尾流的渦結(jié)構(gòu)。將振動情況,壓力分布和渦結(jié)構(gòu)三者聯(lián)系起來即可較完整的描繪各個振動情況的產(chǎn)生機理。隨著θ和L/d的變化,大直徑圓柱表現(xiàn)出不同的振動情況,據(jù)此可以將整個研究區(qū)域分為五個部分,即小圓柱位于上游的共振和弛振區(qū)(I區(qū)),小...

【文章頁數(shù)】：78 頁

【學(xué)位級別】：碩士

【文章目錄】：
摘要
ABSTRACT
ACKNOWLEDGEMENTS
NOMENCLATURE
CHAPTER 1 INTRODUCTION
    1.1 Background
    1.2 Literature review
        1.2.1 Tandem configuration
        1.2.2 Side-by-side configuration
        1.2.3 Staggered configuration
        1.2.4 Excitation and suppression of vibrations
        1.2.5 Present direction
    1.3 Objectives
    1.4 Thesis outline
CHAPTER 2 EXPERIMENTAL SET-UP AND TECHNIQUES
    2.1 Wind tunnel
    2.2 Experimental details
    2.3 Measurement of vibration response
    2.4 Pressure measurement
    2.5 PIV measurement
CHAPTER 3 RESULTS AND DISCUSSION
    3.1 Vibration Response
        3.1.1 Structural properties
        3.1.2 Vibration response of the large cylinder
    3.2 Pressure distribution
        3.2.1 Pressure validation
        3.2.2 Pressure distribution in Regime I
        3.2.3 Pressure distribution in Regime II
        3.2.4 Pressure distribution in Regime III
        3.2.5 Pressure distribution in Regime IV
        3.2.6 Pressure distribution in Regime V
    3.3 PIV measurement
        3.3.1 Regime I
        3.3.2 Regime II
        3.3.3 Regime III
        3.3.4 Regime IV
        3.3.5 Regime V
    3.4 Summary
CONCLUSIONS
REFERENCES



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