双心室心脏泵内部流动非定常数值模拟

Numerical simulation of unsteady blood flows in Bi-ventricular Assist Device

为了研究某新型离心式双心室人工心脏泵内部血液流动特性,采用CFD技术对泵设计工况下的内部流场进行数值模拟分析,获得了该心脏泵内部速度、湍流动能和切应力分布规律,同时得到了泵进口流量、作用在不同过流部件的轴向力和径向力变化情况,并对蜗壳处的压力脉动进行分析.研究结果表明:该型双心室心脏泵内部流场没有出现明显的流动死水区,满足心脏泵的抗血栓要求;泵内压力和切应力分布规律相似,整体分布均匀,满足抗溶血性能的要求;由于心脏泵的整体设计为对称结构,很好地平衡了左右叶轮的轴向力;较小的泵整体结构的径向力和转矩有利于心脏泵抵御瞬态的径向负荷;左右两泵蜗壳处的压力脉动呈现明显的正弦周期性变化规律,均含有6个波峰和6个波谷,且各监测点处压力脉动的主频为叶片通过频率,这是由于叶轮和蜗壳的动静干涉作用.

The unsteady blood flow field in a new type of ventricular assist device,namely the Bi-ventricular Assist Device( BVAD) under the design condition is calculated based on a CFD method. The blood velocity,turbulent kinetic energy and shear stress,mass flow rate in the pump inlets,axial and radial thrusts acted on the different components are obtained; moreover the static pressure fluctuation in the volutes is also analyzed. The results show that there are no notable stagnant regions for thrombus formation in the device. The pressure and shear stress are distributed similarly and uniformly in the device,showing an excellent anti-hemolysis performance. Because of the symmetrical structure of the BVAD,the axial force has been basically balanced by itself. The radial force and torque on the impellers are relatively low,showing the device can endure a transient radial load well. The pressure fluctuations in the volutes vary periodically,exhibiting six peaks and six valleys in time domain. The dominated frequency at every monitoring point is the blade passing frequency of the device due to the rotor-stator interaction.