轴流血泵入口管道流场的数值模拟与实验研究

目的研究轴流血泵入口管道内血流流场分布情况及血栓形成风险。方法利用计算流体力学(computational fluid dynamics,CFD)模拟血泵及入口管道内流动情况,获取血流速度及其分布;用二维粒子成像测速(particle image velocimetry,PIV)系统测试轴流血泵入口管道中心截面内的血液流动情况及三维粒子成像测速系统测试整个管道内的血液流动情况。CFD计算和PIV实验中血泵的转速为8000 r/min,流量为5.0 L/min。通过分析入口管道内的流场分布评价血泵入口管道内的血栓形成风险。结果整个入口管道内不存在回流、涡流和低速流动区域,血液沿管道的流动速度在管壁边界层外由0 m/s迅速增大到0.8 m/s以上。管道内的血液流速集中分布于1.2~1.5 m/s范围,管道内的平均紊流度为0.17。结论由于管道内的流动平稳且不存在回流、涡流和低速流动,因此不易形成血栓。入口管道使血流平稳,有助于改善轴流血泵内的流场。

Numerical simulation and experimental study on the flow field in the inflow cannula of an axial blood pump

Objective To study the blood flow distribution and the risk of thrombus generation in the inflow cannula of an axial blood pump. Methods The blood flow in the inflow cannula was simulated numerically by computational fluid dynamics( CFD) method to obtain the velocity distribution. Then the blood velocity distribution in the central section of the inflow cannula was obtained by two dimensional particle image velocimetry ( PIV) experiment. And the flow distribution in whole inflow cannula was tested with the three dimensional PIV system. The rotational speed of the blood pump was set to 8000 r/min with the flow rate of 5 L/min. Then the possibility of thrombus generation in the axial blood pump inflow cannula was estimated by analyzing the flow property in the inflow cannula. Results There was no spiral flow, backflow, vortex flow or low-speed flow region in the whole inflow cannula. The flow velocity along the cannula wall increased rapidly from 0 m/s to above 0.8 m/s outside the boundary layer. The blood velocity mainly distributed from 1.2 m/s to 1.4 m/s. The turbulence level in the inflow cannula is 0. 17. Conclusions It is hard to form thrombus in the cannula caused by worse blood flow property because there was no backflow, vortex flow or stagnant flow region in the inflow cannula. The inflow cannula can steady the flow entry the blood pump to improve the flow characteristic in the axial blood pump.