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    題名: 剪力流場中的溶血研究
    其他題名: Hemolysis in Shear Flow
    作者: 盧博堅
    貢獻者: 淡江大學水資源及環境工程學系
    關鍵詞: 溶血;溶血指數;Couette 流場;黏滯性應力;雷諾應力;血液實驗;hemolysis;index of hemolysis;Couette flow;viscous shear stress;Reynolds stress;blood experiments
    日期: 2009
    上傳時間: 2010-04-15 16:16:04 (UTC+8)
    摘要: 人工器官如心室輔助器、人工心瓣、導管等,會在心血管中造成非生理性的流 況,這些流況所產生的血流應力會引發血液的破壞,特別是紅血球的損傷,稱為溶 血(hemolysis)。一般以溶血指數(Index of Hemolysis)IH(%)來表示,此溶血指數是切 應力大小及暴露時間的函數。Giersiepen et al.(1990)依據Wurzinger et al.(1986)的實 驗導出的溶血指數模式,IH(%)= 0.785 exp 3.62責105責閃2.416 責t 。此模式廣被應用在計算流 體(CFD)對新設計人工器官的評估上。Wurzinger et al.(1986)的實驗為同心圓內桶轉 動之Couette 黏度儀,為了避免不穩定的Taylor 渦流的產生,其操作範圍暴露時間 為0-700ms,應力範圍為0-255Pa,此範圍太狹窄而不符合現有人工器官的生理範 圍,以致CFD 所計算的溶血指數高估了實際的實驗值。本計畫的目的即是要修正 此模式,並增大其應用的範圍。本計畫將以外圓桶的轉動取代內圓桶的轉動,此種 運作方式可增大其均勻Couette flow 的範圍。而不至於引進不穩定的Taylor vortex。 而暴露時間將由血液的入流及出流量來控制。本計畫將分三年進行: 第一年為均勻剪力流場的建立,將使用流場可視化及雷射都卜勒流速儀,量測 間隙內之流場,以確定在期望的剪應力範圍內可產生均勻的剪力流場。 第二年將採用新鮮的豬的血液進行溶血的測試,而血液的損傷將以溶血指數來 加以量化,並求其和應力大小及暴露時間的溶血指數模式。 第三年將以一簡單的拘限紊流射流場來驗證第二年導出的溶血指數模式,以探 討如何從層流應力所得的模式,應用到紊流場的雷諾應力對血球的破壞。 Artificial internal organs such as left ventricular assist devices, mechanical heart valves, and bypass tubing create non-physiologic flow conditions, which may in turn create stress forces resulting in damage to blood cells, also known as hemolysis. Typically, the amount of damage is indicated by the index of hemolysis (IH, %), which includes parameters such as the magnitude of shear stress and exposure time. Giersiepen et al. (1990) developed the index of hemolysis model, IH(%)= 0.785 exp 3.62責105責閃2.416 責t , based on the Wurzinger et al. (1986) study. This model is widely applied in computational fluid dynamics (CFD) when evaluating new artificial organ designs. To avoid the instability of Taylor vortices, Wurzinger et al. (1986) performed their study with a concentric cylinder Couette viscometer operated with an exposure time of 0-700 ms and stress range of 0-255 Pa. These ranges are narrow and do not correspond with the physiologic ranges of current artificial prostheses, thus resulting in an overestimation of IH. The goal of this study is to reevaluate the IH model and increase its applicability. By replacing the inner cylinder rotating with outer cylinder rotating , the Couette flow ranges can be significantly increased without introducing unstable Taylor vortices. The exposure time will be controlled by the amounts of blood inflow and outflow. This study will be conducted over 3 years: The first year will focus on the establishment of uniform shear flow within the rotating cylinder. The flow field will be studied with flow visualization and laser Doppler anemometry to establish uniform shear flow within the expected shear stress ranges. In the second year, we plan to begin hemolysis studies using pig blood and quantify the extent of damage with the index of hemolysis, and correlate the model with the shear stresses and exposure time. The final year will include evaluation of the IH model from the second year with a confined jet flow. This will allow us to study the application of the IH model, which is derived from laminar shear stress, to turbulent Reynolds stresses and the effects on hemolysis.
    顯示於類別:[水資源及環境工程學系暨研究所] 研究報告

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