过江通道围堰绕流场流速分布特性与紊流宽度影响研究OACSTPCD

Velocity distribution of the flow field around the cofferdam during construction period is a primary issue to be concerned in safety evaluation for ship navigation.Provided that the construction site was determined,velocity distribution of the flow field around the cofferdam is dictated by the inflow velocity and the shape of the cofferdam to a large extent.An insight into the effects of the inflow velocity and the shape of the cofferdam on the velocity distribution of the flow field around the cofferdam is of great significance for the design of the cofferdam and the safety of ship navigation.The numerical model of the flow field around the cofferdam was established.The validation and the accuracy of the numerical method and the effectiveness of the mesh size were verified by experimental results of the physical model.Effects of shapes of the cofferdam and the inflow velocities on the distribution of the longitudinal and transverse flow velocities of the flow field around the cofferdam were discussed.The flow conductivity of three cofferdam shapes such as the rectangular,the dumb-bell and the round-ended was discussed.The navigable clearance width required for safe navigation of ships during construction period were calculated.Results show that a largest turbulent width is caused by the rectangular cofferdam,followed by the dumb-bell cofferdam and the round-ended cofferdam results in a smallest turbulent width.The turbulent width is increased with the increase of the inflow velocity.The turbulence width obstructing the safety of ship navigation is about 1.3 to 2.1 times the cofferdam width D on the navigable side.