Abstract
Ships sailing in the area of a bridge are vulnerable to the influence of complex water flow, due to the complex flow pattern around the bridge pier. Ships often crash into bridge piers, leading to serious economic losses and threating personal safety. Based on the common forms of piers of skew bridges, the hydrodynamic problems encountered during ship–bridge interactions in the area of a skew bridge were studied using particle image velocimetry-based flume testing, physical model testing, and numerical simulation. The influence of the flow angle of attack of a round-ended pier on the force and center of gravity of a ship moving on both sides of a pier is discussed under various ship–bridge transverse spacings. The results show that as a ship passes through the bridge area, the bow roll moment exhibits three peak values: ‘positive’, ‘negative’, and ‘positive’, and the curve of the center of gravity position forms the shape of a ‘straw hat’. With an increase in the flow angle of attack of the pier, the negative peak value and the second positive peak value of the bow roll moment of the ship passing through the back flow side of the pier become greater than those on the upstream side. Moreover, the ship’s navigation attitude is more unstable compared to that upstream, and the ship is at risk of colliding with the pier and sweeping. The width of the restricted water area, determined by the hydrodynamic action between the ship and bridge in the skew bridge area, is the same as that determined by the critical lateral velocity. For the ship class referred to in this study, the current code can also be used in channel design, to safeguard ship and personal safety with piers with a large flow angle of attack.
Highlights
Shi et al [16] simulated the flow field around an elliptical cylinder with an axial ratio range of 0.25–1.0 and a flow angle of attack range of 0–90◦ under a Reynolds number of 150; the flow pattern around the cylinder was divided into three types: steady wake, Kármán wake followed by a steady wake, and Kármán wake followed by a secondary wake
The process of the ship drifting through the bridge pier in the channel with a flow rate of 0.283 m/s was deduced by numerical simulation, when the ship–bridge transverse spacing was 1b
The results showed that the first positive peak value and the second positive peak value of the bow roll moment decrease with the increase in α when the transverse spacing between the ship and pier is constant, and the ship’s attitude is stable
Summary
China has an extensive network of rivers, roads, and railways. Thousands of bridges have been built across rivers; piers have become obstacles to navigation. The piers built in inland river channels block the movement of incoming flow and create a complex 3D flow pattern [1] around them. Ships sailing in these areas are often subjected to turbulence around the piers, and the complex forces cause deflection and deviation, which is not conducive to safe navigation [2]. Shi et al [16] simulated the flow field around an elliptical cylinder with an axial ratio range of 0.25–1.0 and a flow angle of attack range of 0–90◦ under a Reynolds number of 150; the flow pattern around the cylinder was divided into three types: steady wake, Kármán wake followed by a steady wake, and Kármán wake followed by a secondary wake
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