| Summary: | 碩士 === 淡江大學 === 土木工程學系碩士班 === 106 === Wind tunnel experiment is an important research method for wind engineering. The research usually focuses on the steady flow field. The wind engineering research center of Tamkang university has built an actively-controlled multiple fan wind tunnel, which can produce unsteady flow and is closer to the real and smooth flow. This study is divided into three parts. The first part shows the performance of the wind tunnel section and selects the experimental section for subsequent experiments. In the second part, the energy characteristics of unsteady flow will be analyzed by frequency spectrum analysis and wavelet transform. In the third part, a 7x7x78cm square prism will be set up to perform 2D flow field wind pressure experiments to analyze the characteristics of unsteadyflow in the structural response.
For the first part, the average data of each fan outlet will be measured from each section by using Cobra,and then select a suitable section for other experiment. For the second part, the time series of unsteady flow will be measured by using both Cobra and Scanivalve. Compare the differences between unsteady flow and steady flow by using frequency spectrum analysis.Then use wavelet transform to get the timescale spectrum of the unsteady flow time series to get the real energy characteristics of unsteady flow of four different accelerations . Five different displacement spectrums are obtained with a hypothetical aerodynamic function and a hypothetical mechanical function and we can know the resonance response based on it.In the last part, analyze the characteristics of unsteadyflow of four different accelerations in the structural response.
It is expected that we can find out the structural response which can not be seen in traditional wind tunnel experiments.
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