心脏泵悬浮支承结构优化及抗溶血性能分析

Optimization of suspension support structure of cardiac pump and analysis of anti-hemolysis function

目的优化心脏泵的支承结构,以期增加悬浮力和减少溶血。方法设计新型离心式心脏泵的悬浮支承结构,在导流锥附近设计扇形开孔,在悬浮轴承底部设计辅助叶片,并通过计算流体动力学方法比较改进结构前后心脏泵的悬浮力和抗溶血性能。结果改进后心脏泵出入口压差值随流量增大而减小,且随叶轮转速提高而增大,与心脏泵在流体中流量压差情况相同,心脏泵的压差值在允许范围内。叶轮内血液最大速度低于溶血易发生速度(6 m/s),结构改进具有可行性。改进后,叶轮上下表面的压差随着流量的增大而减小,轴向方向向上的悬浮力增大,叶轮受到的悬浮力增加,悬浮性能得到改善;在液力轴承悬浮间隙处,流体平均流速提升,心脏泵底部区域的剪切应力最大值与高剪切应力区域占比均相对降低;液力轴承悬浮间隙处和底部区域溶血减少,改进结构后的心脏泵溶血指数相较于改进前降低了12%。结论优化后的心脏泵悬浮性能得到改善,且溶血指数降低。改进的悬浮结构也可应用于其他离心式心脏泵,其在增加心脏泵悬浮力与减少悬浮轴承间隙处溶血方面具有实际价值。

Objective To optimize the supporting structure of the heart to increase the suspension force and reduce hemolysis.Methods The suspension support structure of a new centrifugal heart pump was designed,the fan-shaped opening was designed near the diversion cone and the auxiliary blade was designed at the bottom of the suspension bearing.The suspension force and hemolysis performance of the heartpump before and after optimization were compared by using the computational fluid dynamics method.Results After improvement,the inlet and outlet pressure difference of the heart pump decreased with the increase of the flow rate,and increased with the increase of the impeller speed.It was the same as the flow pressure difference of the heart pump in the fluid,and the pressure difference of the heart pump was within the allowable range.The maximum blood velocity in the impeller was less than the rate of hemolysis(6 m/s).Structural improvement was feasible.The pressure difference between the upper and lower surfaces of the impeller decreased with the increase of flow rate,and the axial upward suspension force increased,the suspension force of the impeller increased,and the suspension performance was improved.At the suspension gap of the hydraulic bearing,the average fluid velocity increased,the maximum shear stress and the proportion of high shear stress in the bottom region of the heart pump were relatively reduced,and the hemolysis indexes at the suspension gap and the bottom region of the hydraulic bearing was decreased,and the hemolysis indexes of the heart pump was reduced by 12%after the improved structure compared with that before the improvement.Conclusion The suspension performance of the optimized heart pump is improved and the hemolysis indexes are reduced.The improved suspension structure can also be applied to other centrifugal heart pumps,which has practical value in increasing the suspension force of the heart pump and reducing hemolysis in the suspension bearing clearance.