- 學位論文
在不同主動脈形狀下機械心瓣的流動特性
The flow characteristics of the mechanical heart valve installed in three different types of aortic sinus
摘要
Bentall procedure是一種置換心瓣時，一起將心瓣、主動脈竇、以及主動脈後端的血管一起更換的技術。因為我們在換至心瓣時，可能因為手術縫合的緣故會造成主動脈竇的消失，所以我們通常會換上人工的對稱型主動脈竇，不過如今也有許多人使用正常型主動脈竇以及無竇型主動脈竇。在本實驗中使用的心瓣為SJM是被發明於1977年，如今還是最多臨床上所使用的機械心瓣，在本實驗中，我們知道不同的邊界條件會造成不同的流動特性，所以我們的目的就是比較sjm心瓣裝置於三種不同的主動脈竇並且利用脈動是流場來模擬人體心臟循環，進而利用dpiv求得在主動脈竇的速度場與渦度場在六種不同的相位中。我們從速度場圖可以觀察到在正常型主動脈竇以及對稱型主動脈竇中可以看到環流產生於竇裡面，並且從心瓣葉片以及環座旁也可以觀察到shear layer的存在，由此我們可以知道不同形狀的主動脈會造成不同的速度場以及窩度場，進而可以更了解機械心瓣是否會對於人體造成不好的影響。
並列摘要
Bentall Procedure is a surgery which simultaneous replacement of a diseased aortic valve, aorta root and ascending aorta. Because when we replacement the aorta valve, the aorta sinus will disappear by suture, so we usually replace the artificial symmetric aorta sinus when we replace the aorta valve. But in the present work, three sinus aorta and aorta without sinus have been considered.SJM is the most popular to use in the clinical. In this study, we know different boundary condition cause different flow characteristic. The aim of this is compare with the SJM valve installed in three different type aorta sinus in the Pulsatile flow, and we use DPIV to take six phase in a cycle. Than we compute the velocity field and vorticity flow in each phase.and we found the three sinus aorta and symmetric sinus aorta have recirculateion flow in the sinus, and the shear layer has been found beside the valve and the valve ring. so we can understand the different of the types of aorta will be different velocity filed and vorticity field, and then we can know if the mechanical heart valve has bed influence for the human?