From the School of Engineering and Materials Science, Queen Mary University of London, London, United Kingdom.
Department of Cardiology, Barts and the London NHS Trust, London Chest Hospital, London, United Kingdom.
ASAIO J. 2018 Sep/Oct;64(5):643-650. doi: 10.1097/MAT.0000000000000700.
In centrifugal rotary blood pumps (RBP), clearances are a critical parameter in determining blood trauma. This study investigates the effect of axial clearance (Cax) and radial clearance (Crad) on the hydrodynamic and hemolytic performance of a centrifugal RBP. A centrifugal pump was parameterized so that it could be defined by geometric variables Cax and Crad. Optimal Latin hypercube sampling was used to determine design points based on Cax, Crad, and rotor speed (ω). For each design point, a computational simulation was conducted to determine efficiency (η) and normalized index of hemolysis (NIH). Next, a response surface (RS) was created to estimate these performance parameters based on the design variables. The results show that for a given Cax, when Crad is decreased, η increases until Crad = 0.15 mm, beyond which η deceases. For a given Crad, Cax has a unimodal relationship with η. The NIH has a unimodal relationship with both Cax and Crad. The mechanisms behind these relationships were investigated by various analytical methods. It was found that vortices in the secondary flow paths were a critical factor in determining efficiency and hemolysis. The optimal clearance values discerned in this study are only valid for the specific impeller geometry and operating conditions analyzed.
在离心式旋转血泵（RBP）中，间隙是决定血液创伤的关键参数。本研究探讨了轴向间隙（Cax）和径向间隙（Crad）对离心式 RBP 的水动力和溶血性能的影响。通过参数化离心式泵，可以通过几何变量 Cax 和 Crad 来定义其特性。采用最优拉丁超立方抽样（Optimal Latin hypercube sampling），根据 Cax、Crad 和转子转速（ω）确定设计点。对于每个设计点，进行计算模拟以确定效率（η）和归一化溶血指数（NIH）。然后，根据设计变量创建响应面（RS）来估计这些性能参数。结果表明，对于给定的 Cax，当 Crad 减小时，η 会增加，直到 Crad = 0.15mm，超过该值后，η 会下降。对于给定的 Crad，Cax 与 η 呈单峰关系。NIH 与 Cax 和 Crad 均呈单峰关系。通过各种分析方法研究了这些关系背后的机制。结果发现，二次流道中的涡流是决定效率和溶血的关键因素。本研究中确定的最佳间隙值仅适用于分析的特定叶轮几何形状和操作条件。
