| Summary: | 碩士 === 國立中央大學 === 土木工程研究所 === 91 === This study experimentally investigates the pressure distribution on the surface of three-dimensional circular cylinder in a boundary layer flow. The experiments were carried out in an atmospheric boundary layer wind tunnel. The flow conditions include three different kinds of surface roughness. Instantaneous fluctuating wind pressures were measured by an electronic pressure scanner. Based on the pressure measurement, the distributions of mean, rms Cprms, peak pressure Cpp and separation point can be calculated. It was found that the maximum Cprms occurs at the location of minimum negative pressure. Also, the separation point and the location of minimum negative pressure will move toward upstream direction as surface roughness increase. Even under the same surface roughness, the separation point will move within certain range in turbulent flow. The moving range of separation point will decrease as surface roughness increase. The experimental results also revealed that the probability of pressure fluctuations for positive pressure are close to the Gaussian distribution function. On the other hand, negative pressure side was skewed and did not necessary follow Gaussian distribution.
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