Comparison of opening behaviors of monoleaflet tilting disc valves using a high speed video camera

We have been studying the opening action of a monoleaflet tilting disc valve, (Bjork-Shiley Monostrut; sewing ring diameter: 23 mm, BSM), and reported last year that the valve opening motion depended on the early period flow rate pattern from 0 to 20 msec. This time, the Bjork-Shiley Spherical and the St. Vincent's valve were tested. All three valves are monoleaflet tilting disc valves with the same disc diameter but with disc shapes that are different from each other. Each valve was incorporated in a mitral position of a mock circulatory system driven by pneumatic pressure. Changes in valvular disc angle were measured at 500 frames per second using a high speed videocamera. We found the opening motion of the two valves depended on the early period flow rate pattern (from 0 to 20 msec; the same as the BSM valve). Using the moment of force values obtained, drag and lift coefficients (C(D) and C(L)) of each valve were calculated. Results showed that the C(D) and the C(L) were enlarged up to 3.0 x 10⁴ at the early opening period. This result was speculated to be a cause of the influence of the flow pattern on the valve action at the same period.