基于CFD的粗糙度及污损附着对船舶阻力的影响

Effect of Surface Roughness and Fouling on Ship Resistance Based on CFD Analysis

目的研究船体表面粗糙度及污损附着在不同航速下对航行阻力的影响。方法参考船体粗糙表面条件下的阻力估算方法,并通过目检法对船舶污底分级,由船体附着的生物类型判断此时污损附着的严重程度。划分三种不同的船体表面条件,对应建立三种模型,采用计算流体力学(CFD)方法,使用FLUENT软件进行数值模拟。将仿真结果与经验结论进行对比,分析阻力的增长情况与阻力性质。结果船体表面条件越差,增加的航行阻力越大。同一表面条件下,增加的航行阻力随航速的增大而增大。在粗糙度(包含轻度污底)和中度污底情况下,增加的航行阻力主要为摩擦阻力;重度污底情况下,增加的航行阻力不再以摩擦阻力为主,粘压阻力、兴波阻力所占比例会增大。结论在重度污底的情况下,经验推荐的摩擦补贴系数已不适用于实际情况,数值模拟方法的计算结果可供参考。通过降低航速来减少增阻适用于任何表面条件。

Effects of surface roughness and fouling on ship resistance are analyzed by numerical simulation, the fouling covered on hull are graded through the visual inspection, three different hull surface conditions are divided corresponding to three models used to simulate by FLUENT software through computational fluid dynamics （CFD） method. The simulation re- suits are compared with the empirical conclusions, and the resistance growth and resistance properties are analyzed. It shows that poor hull surface conditions make ship resistance increase, added resistance increase with speed grow under the same sur- face condition. On the condition of surface roughness （including mild fouling） and moderate fouling, the increased resistance is mainly frictional resistance, however, there is not the same under the condition of heavy fouling that viscous pressure resistance, wave resistance increase more than frictional resistance, and the recommended coefficient is not applicable to the reality situa- tion under the condition of heavy fouling, the results calculated though CFD method are useful. Speed reduce is helpful to drag reduce on any surface condition of ship.