Abstract:

The fluid motion characteristics of the membrane oxygenator have an important influence on its performance, the computational fluid dynamics (CFD) hydrodynamic analysis of the oxygenator model by computational fluid dynamics is one of the important methods to predict its performance. Based on the pressure drop experiment, the viscous drag coefficient of the oxygenator fiber bundle was calculated and an isotropic porous media model was established. The RNGk-ε turbulence model was used to calculate the internal flow field of the oxygenator under different flow rates, and the cloud velocity map of blood velocity, pressure and wall shear stress was obtained. It is found that with the increase of flow rate, the internal velocity gradient distribution of the oxygenator is basically unchanged, the pressure distribution is inclined and gradually decreases, and most of the pressure loss is located in the fiber bundle, of which 53.3% is located in the oxygenation chamber, and 42.6% is located in the temperature chamber. The inlet and outlet locations of the oxygenator blood are high-risk areas of blood damage. The standard hemolysis index NIH of the oxygenator was calculated using the hemolysis numerical prediction model. The results show that the simulation results of the isotropic porous medium model are basically consistent with the experimental results at 1.65—3.00L/min. The deviation between the simulated value and the experimental value will increase with the increase of the liquid flow rate; at 1.65—6.00L/min, the standard hemolysis index NIH is 0.0084—0.0835g/100L, which meets the physiologically acceptable use range of human body.

Key words: membrane, oxygenator, computational fluid dynamics, porous media, hemolysis

摘要：

膜式氧合器内部流体运动特性对其性能有重要影响，利用计算流体力学（CFD）对氧合器模型进行流体动力学分析是预测其性能的重要方法之一。本文基于压降实验计算氧合器纤维束的黏性阻力系数，建立了各向同性多孔介质模型。采用RNGk-ε湍流模型对不同流量下氧合器内部流场进行计算，得到了血液速度、压力和壁面剪切应力分布云图。发现随着流量的增加，氧合器内部速度梯度分布形式基本保持不变，压力分布呈倾斜状态且逐渐减小，大部分压力损失位于纤维束内，其中53.3%位于氧合室，42.6%位于变温室。氧合器血液的入口及出口位置为血液损伤的高发区域。采用溶血数值预估模型计算得到了氧合器的标准溶血指数NIH。结果表明：在低流量1.65～3.00L/min下，各向同性多孔介质模型的模拟结果与实验结果基本一致，模拟数值与实验数值的偏差会随着液体流量的增加而变大；流量为1.65～6.00L/min时，标准溶血指数NIH为0.0084～0.0835g/100L，满足人体生理允许的使用范围。

关键词: 膜, 氧合器, 计算流体力学, 多孔介质, 溶血