基于CFD的浅水条件下工程船水阻力快速预报方法

Rapid Prediction Method for Water Resistance of Engineering Ships in Shallow Water Based on CFD

为准确预报工程船的流阻力,以杭州湾铁路桥施工中的“水欣麒”号打桩船为研究对象,参考同类型船的阻力系数试验值,采用计算流体力学(CFD)方法对考虑锚泊约束的打桩船阻力进行预报。数值计算结果表明:在深水条件下,相比采用悬链线约束船舶得到的船舶阻力,完全限制船舶运动的计算误差不超过1.52%;在浅水条件下,锚泊无法完全限制船舶运动,船舶升沉、横倾和横摇对船舶阻力计算的影响较大,此时不考虑船舶运动得到的阻力相比悬链线约束条件下的阻力计算结果偏小,其误差最大达到26.6%;完全放开船舶的升沉和横摇自由度之后,计算得到的船舶横倾和横摇值比锚泊约束下的结果更大导致船舶兴波更剧烈,兴波阻力变大导致计算得到的总阻力偏大;考虑到不同锚泊方案对船舶运动的限制程度不同,从安全性的角度考虑,进行较为保守的阻力修正是有必要的。

To accurately predict the flow resistance of engineering ships,the"Shuixinqi"pile driving ship used in the construction of the Hangzhou bay railway bridge is taken as the research object.By referring to the resistance coefficient test values of similar ships,the computational fluid dynamics(CFD)method is used to predict the resistance of pile driving ships considering the anchorage constraints.The numerical calculation results show that under deep water conditions,compared with the ship resistance obtained by constraining the ship with a catenary,the calculation error of completely restricting the ship movement does not exceed 1.52%;under shallow water conditions,anchoring cannot completely restrict the ship movement,and the effects of the ship heave,roll,and sway on the calculation of the ship resistance are significant.At this stage,the resistance calculated without considering ship movement is less than that under catenary constraints,with a maximum error of 26.6%;after full release of the degrees of freedom of ship heave and roll,the calculated values of the ship roll and pitch are greater than those under anchor constraints,resulting in more severe wave making and increased wave making resistance,leading to a greater calculated total resistance;considering that different anchoring schemes have different degrees of restriction on ship movement,it is necessary to make conservative resistance corrections from a safety perspective.