Singapore: World Scientific Publishing Co. Pte. Ltd.
The main purpose of this study was to carry out a detailed study of the flow fields between the leaflets of widely used bileaflet heart valves. In conventional research, the sewing ring of the valve acts as an obstacle for measurement. In addition, the small space in bentween the leaflets limits the amount of detailed measurement that can be done. Therefore, in this study two enlarged semicircular plates were used to mimic the actual fully-opened leaflets during peak systole and the flow field was measured according to dynamic similarity. Flow visualization technique and a laser Doppler anemometer (LDA) were used to obtain qualitative and quantitative data, respectively, of the various turbulence characteristics of the flow between the plates and downstream near field. The spacings and angles of the plates were changed to study the effects that their interactions had on the flow field. According to the experimental results of the visualized flow fields, the deflection of the central flow field is more obvious as the angle of bileaflets becomes larger, mainly due to the Coanda effect. However, the direction of deflection is not specific but is especially obvious when the opening angle is 12 °. As the interval increases, the Coanda effect tends to decrease. The LDA measurements show that the maximum shear stress is small when the leaflets are fully open and the opening angle is 0°∼ 6 °, thus lowering the possibility of thrombosis.