許多的研究表示，心臟疾病是現代人死亡原因前幾名。穴蝕氣泡當機械心瓣關閉時瞬間形成，這會破壞血球細胞與心瓣完整性，是一個眾所周知被廣泛研究的現象。在MHV關閉期間，擠壓流通過狹縫生產噴射流並在下游捲起渦旋。同樣的，高速滲漏間隙流可能捲起渦旋。向前的流場與尾流相互作用，在擋水板後面回彈也可能會導致渦流的形成。利用固定葉片間的夾縫模擬血液回流時通過夾縫產生出高速的噴射流。此研究我們使用PIV仔細測量在MHV中迴流流場的渦流結構。我們測量渦流半徑，最大切向速度，循環強度和計算壓降，這使我們能夠量化評估渦流在MHV穴蝕中的形式。若渦流中心壓低低於飽和蒸汽壓(-740mmHg)即能發生穴蝕現象，本實驗所量測出來的最大壓降為172.042mmHg，並不會有穴蝕現象產生。

A lot of studies have shown that heart disease plays an important role of death of modern people. The instantaneous formation of cavitation bubbles at mechanical heart valve closing, which subsequently damage blood cells and the valve integrity, is a well-known and widely studied phenomenon. During MHV closure, squeeze flow through the gaps can produce jet flows that roll up downstream into vortices. Similarly, high-speed leakage flow may roll up into vortices. Interactions between the forward flow and fluid trailing behind the occluder after rebound may also result in vortex formation. We use the fixed leaflets simulated blood retrograde flow through the gap to produce a high-speed jet. We have carefully measured the vortex structure in the MHV regurgitant flow field using PIV. We measured the vortex radius, maximum tangential velocity, circulation strength, and calculated pressure drop, which allows us to quantitatively evaluate the vortices in MHV cavitation formation. The maximum pressure drop in the vortex center is 172.042mmHg. Since cavitation formation requires the locale pressure to drop below vapor pressure (about -740 mmHg), Our results clearly showed that vortex formation with a pressure drop of this order of magnitude cannot provide significant contribution to mechanical heart valve cavitation.

目錄
目錄	iv
表目錄	v
圖目錄	vi
第一章 緒論	1
1-1前言	1
1-2研究動機與目的	3
1-3研究過程	6
第二章 文獻回顧	8
2-1機械心瓣	8
2-2穴蝕成因	10
第三章 實驗設置與方法	14
3-1 實驗架設	14
3-2壓力計	16
3-3數位質點影像測速儀(DPIV)	17
3-4實驗條件設置	19
3-5公式運算	20
3-6資料分析	26
第四章 結果與討論	29
4-1 不同條件之最大速度的渦流分析	30
4-2 渦流歷程分析	32
4-3 渦流與穴蝕關係	34
第五章 結論與實驗建議	35
5-1 結論	35
5-2 實驗建議	35
參考文獻	36

 
表目錄
表2-1 渦流中心點預估壓降	40
表4-1 夾縫出口左側渦流半徑R(mm)	40
表4-2 夾縫出口左側渦流最大切向速度Vθ(m/s)	40
表4-3 夾縫出口左側環流量Γ(m2/s)	40
表4-4 夾縫出口左側渦流壓降dP(mmHg)	40
表4-5 夾縫出口右側渦流半徑R(mm)	41
表4-6 夾縫出口右側渦流最大切向速度Vθ(m/s)	41
表4-7 夾縫出口右側環流量Γ(m2/s)	41
表4-8 夾縫出口右側渦流壓降dP(mmHg)	41
 
圖目錄
圖1-1研究流程示意圖	42
圖3-1 夾縫	43
圖3-2 系統架構示意圖	43
圖3-3 壓力腔與主體腔實體圖	44
圖3-4 壓力感應器型號105C12	44
圖3-5 訊號配合訊號調節器(sensor signal conditioner)型號480E09	45
圖3-6 訊號產生器	45
圖3-7 DPIV雷射光源	46
圖3-8 Rankine vortex model示意圖[23]	46
圖3-9 DPIV分析介面	47
圖4-1 v=2.52m/s於t0 + 15ms瞬時流場向量圖	47
圖4-2 v=2.52m/s於t0 + 20ms瞬時流場向量圖	48
圖4-3 v=2.52m/s於t0 + 30ms瞬時流場向量圖	48
圖4-4 v=3.54m/s於t0 + 15ms瞬時流場向量圖	49
圖4-5 v=3.54m/s於t0 + 20ms瞬時流場向量圖	49
圖4-6 v=3.54m/s於t0 + 30ms瞬時流場向量圖	50
圖4-7 v=9.54m/s於t0 + 15ms瞬時流場向量圖	50
圖4-8 v=9.54m/s於t0 + 20ms瞬時流場向量圖	51
圖4-9 v=9.54m/s於t0 + 30ms瞬時流場向量圖	51
圖4-10 夾縫出口左側渦流半徑R	52
圖4-11 夾縫出口左側渦流最大切向速度Vθ	52
圖4-12 夾縫出口左側環流量Γ	53
圖4-13 夾縫出口左側渦流壓降dP	53
圖4-14 夾縫出口右側渦流半徑R	54
圖4-15 夾縫出口右側渦流最大切向速度Vθ	54
圖4-16 夾縫出口左側環流量Γ	55
圖4-17 夾縫出口右側渦流壓降dP	55

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