Experiments on Flow Past Two Side by Side Semicircular Flat Plates
| Autor: | Weng, Jia-Hurng, 翁嘉宏 |
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| Rok vydání: | 1998 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 86 The main purpose of this study was to carry out a detailed study of the flowfields between the leaflets of widely used bileaflet heart valves. In conventionalresearch, the sewing ring of the valve acts as an obstacle for measurement. In addition, the small space in between the leaflets limits the amount of detailed measurement, which 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 Laser Doppler anemometer (LDA) were used toobtain qualitative and quantitative data, respectively of the various turbulence characteristics of the flow between the plates and downstream near the wake. The spacings and angles of the plates were changed to study their interactions. Shear stresses in the flow and along the walls of the plates were also measured to evaluate the damage inflicted on red blood cells and platelets. According to experimental result of the visualization flow fields, the deflection of the central flow field is more obvious as the angle of bileaflets becomes larger because of the Coanda effect. However, the direction of deflection is not specific and is especially obvious when the plates' angle is 12° and the interval is 7.5 mm. As the interval increases, the Coanda effect tends to decrease. The LDA measurements show that the maximum shear stress is smallest when the plate are fully open and the angle between a single leaflet and streamwise flow is 0°~6°, thus lowering the possibility of thrombosis. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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