叶顶间隙对人工心脏泵血液相容性影响的数值研究

采用定常和非定常数值方法系统研究了离心血泵在供压173 mmHg时,4组不同叶顶间隙下的血流动力学特性和血液相容性。所研究的间隙分别为5.0、2.0、1.0 mm和0.2 mm,对速度、湍动能等参数的分布规律以及标准溶血指数(normalized index of hemolysis,NIH)随叶顶间隙大小的变化规律进行了研究。结果表明:在流量3.0 L/min,供压173 mmHg工况下,原型血泵有较好的血液相容性;随着叶顶间隙的减小,最大切应力与标准溶血指数呈显著单峰变化趋势,在1.0 mm间隙结构取得最低标准溶血指数0.000 5 g/100 L,并降低了在叶轮侧壁与泵壳下壁面的狭缝内形成血栓的风险;定常与非定常的结果对比表明:定常结果往往会过小的预测溶血,瞬态标准溶血指数随叶轮转动呈周期性变化,其平均值与定常结果相差在5%以内。 

Numerical research on effects of blade tip clearances onthe hemocompatibility of artificial heart pump

Steady and unsteady numerical simulations were carried out to systematically research the hemodynamic performance and hemocompatibility of four groups of centrifugal blood pumps with different blade tip clearance at 173 mmHg. The gaps studied were 5.0 mm, 2.0 mm, 1.0 mm and 0.2 mm, respectively, the distribution of parameters and the changes of normalized index of hemolysis with the size of blade tip clearance were researched. The results showed that the origin pump had good hemocompatibility at 3.0 L/min against a pressure head of 173 mmHg; with the decrease of blade tip clearance, the max stress and the normalized index of hemolysis showed a single peak and the minimum normalized index of hemolysis 0.000 5 g/100 L was obtained in the 1.0 mm clearance structure, which reduced the risk of thrombosis in the gap between the outer impeller walls and the lower housing cavity walls; compared with the results of the unsteady simulation: steady results were often too small to predict hemolysis, the transient normalized index of hemolysis changed periodically with the impeller rotation, and the difference between its mean and the steady results was within 5%.