Characteristics of water level distribution around a 10 000-ton cargo ship towing a navigable vessel in a 30-meter wide tunnel
As a hidden navigation channel through the mountain,the water level is a key factor affecting the navigation of the super-limited navigation channel for the hydraulic conditions of tunnel navigation.In order to investigate the change rule of water level around the cargo ship when it is towing in the navigation tunnel and the hydraulic characteristics of navigation caused by the change of water level.A 1:40 physical model test system was established,which comprised the tunnel and the ship towing device positioned on the top of the tunnel.Under varying water depth conditions,five levels of towing speed physical tests were conducted,with emphasis on the changes in water level occurring both in front of and behind the ship within a distance twice the length of the ship.These tests also analyzed the factors influencing the fluctuations in water level,as well as the alterations in the ship′s longitudinal inclination angle.The results are shown to indicate that:the increase in towing speed results in an elevation of water level in front of the ship and a decrease behind it,yet within a moderate towing speed range(0.5 m/s to 1.5 m/s),minimal changes in water level are observed,enhancing navigation safety.An increase in tunnel water depth diminishes the magnitude of water level elevation in front of and decrease behind the ship,particularly within a water depth range of 6 m to 8 m where minimal water level changes occur,improving navigational conditions.As towing speed increases,water level fluctuations both in front of and behind the ship are reduced,resulting in small changes in water level.Additionally,the ship′s longitudinal inclination angle increases with the rise in towing speed,while it decreases with the increase in tunnel depth.Moderate control of towing speed within a water depth range of 6m to 8m is found to be effective in reducing the ship′s longitudinal inclination angle,thereby enhancing navigation stability and safety.The findings of this study serve as a valuable reference for the key technology of ship towing in navigable tunnels.
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