碩士 / 國立成功大學 / 水利及海洋工程學系 / 78 / To investigate the characteristics of wave forces on the submerged pipeline near seabed, a series of measurements had been carried out in an U-tube. The main feature of the U-tube is that the water velocity and acceleration in the flow field can be predicted accurately giving a better basis for wave force analysis. Besides, the range of KC number in the U-tube can be extended to 100 covering almost the whole range of the parameter in the practical engineering design cases.
Experimental results show that the effect of seabed boundary can be neglected as the gap between the pipeline and the bottom is larger than one pipe diameter. Within one diameter, both inline and lift force coefficients increase obviously as e/D (gap ratio) decreases. The total force on pipeline of the smallest gap ratio (e/D=0. 031) exceeds two times of that of free stream condition (e/D>l). The results of inertia and lift force coefficients are compared with the potential theory, it show that the theory fails to express lift force coefficient, and can express inertia force coefficient only qualitatively but not quantitatively.
The frequency of the lift force increases with KC number and is independent from the gap ratio. It can be as large as 10 times of that of the incident oscillating flow, however, its energy distributes still in low frequency region.
| Identifer | oai:union.ndltd.org:TW/078NCKU3083002 |
| Date | January 1990 |
| Creators | 周恒豪 |
| Contributors | 高家俊 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 53 |
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