碩士 / 國立海洋大學 / 河海工程學系 / 90 / For this experimental study a plane basin was utilized to simulate the propeller-induced bed scouring due to a container ship with a model propeller of six blades. The experiments comprises of two key factors: the axial velocity and the scour for four rotational speeds of 200, 250, 300 and 350RPM, respectively. The measurements of the vertical distributions of axial velocity and profiles of scour depths at different motive time were compared with the theoretical values.
As a result, the measured efflux velocities Vo highly matches those calculated by Fuehrer and Romisch (1977) and by EAU (1996) but slightly differed with those by Hashmi (1993). The measurements of vertical distributions of axial velocity are found to well agree with Hamill (1987) on maximum velocities and with Hamill (1996) on vertical distribution profiles particularly near axial distance X of 3 times of the propeller diameter Dp. Greater differences in axial velocities are found at between the axis (Z=0) and location of maximum velocity in lower rotation speed, e.g. 200RPM. For decreasing trends of the maximum axial velocities along axial direction (X), the measured values are always higher than the theoretical values except for the case of 300 RPM.
The maximum scour depths usually occurred at distances of about between X= 2 to 3Dp for different rotation speeds and motive time near the zone boundary of flow establishment and established flow. The slopes of the scour holes became steeper with increasing motive time and greater rotational speeds while the scour ranges extended downstream. Furthermore, the fitting curves of the development of maximum scour depth with time are found to be exponential type approximating a steady limit as the motive time exceeding about 2 hours.
| Identifer | oai:union.ndltd.org:TW/090NTOU0192050 |
| Date | January 2002 |
| Creators | CHEN.CHEN-CHIH, 陳建志 |
| Contributors | TZANG SHIAW-YIH, 臧效義 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 99 |
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