Purpose

Mechanical heart valves (MHVs) are widely used to replace diseased heart valves, but it may suffer from cavitation due to the rapid closing velocity of the leaflets, resulting in the damage of red blood cells and platelets. The aim of this study is to apply computational fluid dynamics (CFD) method to investigate the cavitation in bileaflets mechanical heart valves (BMHVs) and discuss the effects of the conduit and leaflet geometries on cavitation intensity.

Methods

Firstly, CFD method together with moving-grid technology were applied and validated by comparing with experimental results obtained from other literature. Then the leaflets movement and the flow rate of BMHVs with different conduit geometries and leaflet geometries are compared. At last, the duration time of the saturated vapor pressure and the closing velocity of leaflets at the instant of valve closure were used to represent the cavitation intensity.

Results

Larger closing velocity of leaflets at the instant of valve closure means higher cavitation intensity. For BMHVs with different conduit geometries, the conduit with Valsalva sinuses has the maximum cavitation intensity and the straight conduit has the minimum cavitation intensity, but the leaflets cannot reach the fully opened state in a straight conduit. For BMHVs with different leaflet geometries, in order to minimize the cavitation intensity, the leaflets are better to have a large thickness and a small rotational radius.

Conclusion

CFD method is a promising method to deal with cavitation in BMHVs, and the closing velocity of leaflets has the same trend with the cavitation intensity. By using CFD method, the effects of the conduit geometry and the leaflet geometry on cavitaion in BMHVs are found out.

中文翻译：

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双叶机械心脏瓣膜的空化抑制。

目的

机械心脏瓣膜 (MHV) 被广泛用于替换患病的心脏瓣膜，但由于瓣叶关闭速度快，它可能会发生空化，导致红细胞和血小板受损。本研究的目的是应用计算流体动力学 (CFD) 方法研究双叶机械心脏瓣膜 (BMHV) 中的空化，并讨论导管和单叶几何形状对空化强度的影响。

方法

首先，通过与其他文献中获得的实验结果进行比较，将CFD方法与移动网格技术结合起来进行应用和验证。然后比较了具有不同导管几何形状和小叶几何形状的 BMHV 的小叶运动和流速。最后用瓣膜关闭瞬间饱和蒸气压的持续时间和瓣叶关闭速度来表示空化强度。

结果

瓣膜关闭瞬间瓣叶闭合速度越大意味着空化强度越高。对于具有不同导管几何形状的 BMHV，具有 Valsalva 窦的导管的空化强度最大，直导管的空化强度最小，但在直导管中瓣叶不能达到完全打开状态。对于具有不同小叶几何形状的 BMHV，为了最小化空化强度，小叶最好具有较大的厚度和较小的旋转半径。

结论

CFD方法是处理BMHV中空化的一种很有前景的方法，并且小叶的闭合速度与空化强度具有相同的趋势。通过使用 CFD 方法，找出了导管几何形状和小叶几何形状对 BMHV 中空化的影响。