微型轴流式血泵叶轮的结构优化设计和流场有限元计算分析

Impeller Optimization and Computational Fluid Dynamics Analysis of Micro-Axial Blood Pumps

微型轴流式血泵被广泛运用于短期心脏循环辅助,其重要指标是转速、扬程、流量和流场分布。采用计算流体力学方法对血泵流场进行了数值模拟,得到血泵的扬程和流场分布,验证得出:传统升力法不能满足要求。为此提出了两种新型的轴流血泵DAVa和DAVb,叶轮数4,外径18mm,内径6.3mm,长度21mm,从轮毂到轮缘径向5个均匀分布的截面分别采用NACA10-NACA6翼型,相邻切面的安装角差为内切面翼型安装角的1/3和1/2。流体计算结果:随着轮毂处安装角从50°增加到80°,DAVb的扬程均大于DAVa,DAVb扬程平缓增加,DAVa则在80°处有一个突增;DAVa的脱流和湍流、径向流都明显小于DAVb。由此得出,轴流泵的扬程和叶轮安装角成正比关系,采用较为合适的叶轮扭转度有利于减小湍流、尾流和径向流等不稳定流场损耗现象。

Commonly, micro-axial blood pump is widely utilized for the cardiac assist of failing natural heart. The pressure-flow, rotation speed and flow fluid can be studied through CFD analyses. Because its performance differs from industrial axial blood pumps, traditional industrial designing method doesn＇t work. Two types of micro-axial pumps-DAVa and DAVb, are put forward, with impeller number 4, outer diameter 18mm, inner diameter 6.3mm and length 21mm. NACA10-NACA6 are applied to construct the impeller＇ s 5 radial sections, each radial section＇ s discharge angle is as 4/3 or 3/2 as the inner one. CFD analyses result shows： DAVb＇ s pressure head is larger than that of DAVa, and with the inner discharge angle increases from 50° to 80° DAVb＇ s pressure head increases continuously while DAVa suddenly increases at discharge angle 80°. Besides, DAVa＇ s has torrential and radial flow less than DAVb. Therefore, pressure head increases with discharge angle increases, and proper impeller torsion helps to decrease turbulence, wake and radial flow.