| Summary: | 碩士 === 國立臺灣海洋大學 === 河海工程學系 === 95 === Abstract
This study consists of two tasks, one of which investigates in Port of Kaohsiung bed scour distributions at container ship berths. The other is aimed at experimentally measuring flow fields by stern propeller in the vicinity of a quay wall. Experiments were carried out in a water basin with utilization of a model 6-blade propeller of reduction ratio of 1/30 to a prototype container ship’s propeller.
Analysis of hydrograph of 12 container ship berths has shown four types of scour pits based on the location of maximum scour depth. Scour pits of type 1 are mainly located in the vicinity of the toe of quay wall. Scour pits of type 2 are located within 20 m to the quay wall. Scour pits of type 3 are located in the middle of the berths. Scour pits of type 4 are located from 60 to 70 m normal to the quay wall. The scour pits are thought to be primarily due to flows induced by the stern propeller during berthing operations.
Experimental tests being aimed at zones nearby the quay wall also consist of two tasks, that is, measurements of velocity fields over a rigid bed and scour development on a sandy bed due to propeller flows. Measurements of velocity fields consider three propeller rotation rate (120, 180 and 240 RPM) with three distances of 4Dp, 3Dp and 2Dp (Dp is the propeller’s diameter) between quay wall and central core of propeller. Meanwhile, the measurements of bed scour profiles consider only the quay wall distance of 2 Dp and rotation speeds of 180 and 240 RPM for intervals of 10、20、30、60 and 120 min, respectively. The results illustrate that diffused propeller-induced velocity components in axial and vertical directions Vx and Vz become larger with increases of quay wall distance and rotational speed. Thus, scour pits are gradually developed near the toe of a quay wall due to propeller flows. For longer actions, they will continue to grow larger in size and the maximum scour depth and the longer axis of the scour pits increase as well.
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