| Summary: | 碩士 === 國立海洋大學 === 造船工程學系 === 87 === An image process that can be applied to determine the instantaneous velocity of turbulent flow is proposed in this study. Since the frequency of the generated, alternating color, laser sheet can be as high as 10000 Hz, the instantaneous turbulence structure can be easily captured by the Alternating Color Image Anemometry. The mean velocity of the flow is first determined within an interrogating window from the Digital Velocity Vector (DVV) method. All the possible velocity vectors determined from DVV for a single particle are then compared with the mean velocity. The velocity vector with smallest difference to the mean velocity, and if their difference is small than a specified amount, the velocity vector is selected as the instantaneous velocity of the particle. There four, applying the ACIA together with the DVV method, the instantaneous velocity of the turbulent flows can be easily measured.
A constant speed, rotating disk, and then a two-dimensional turbulent channel flow are measured by the proposed method. Satisfactory result are obtained.
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