KCS艏艉型线优化及其对推进效率的影响

Bow and Stern Optimization of KCS and Effect on Propulsive Efficiency

对KCS的船首和船尾型线优化开展研究。船体采用径向基函数描述,艏部型线以减小总阻力为目标,艉部型线则侧重于降低尾流不均匀度,以期提高推进效率。在优化过程中,利用基于拉丁超立方采样点构建Kriging近似模型替代直接计算流体力学(CFD)模拟。分别采用多岛遗传算法和非支配排序遗传算法-Ⅱ开展单目标和多目标优化,避免优化的早熟。结果表明,在服务航速下,优化船型的总阻力降低了1.36%,优化船型的伴流目标函数降低了10.2%。在此基础上,进一步针对优化过程中产生的3个优化船型以及原始船型,选用KP505桨进行自航模拟,结果显示虽然阻力有些许增大,但伴流不均匀度明显降低的优化船型的推进效率更优,相对于原始船型,其推进效率最高提升了1.08%。

The bow and stern profile optimization of KCS is studied.Shape of the hull form is expressed in a radial basis function to facilitate its deformation during the course of optimization.The bow shape aims at the reduction of total resistance,while the stern optimization focuses towards the improvement of the quality of the wake to increase propulsion efficiency potentially.In the optimization,a Kriging model is constructed based on Latin hypercube sampling to replace the evaluation of hydrodynamic performances of the ship by means of direct CFD simulation.Multi-island genetic algorithm and non-dominated sorting genetic algorithm-II are employed in the optimization for single object and multiple objects problems,respectively,and the pre-mature termination at local optimal solution rather than global optimal solution is prevented.The result shows that,the total resistance of KCS at service speed is reduced by 1.36%and the wake object function(WOF),proposed by MARIN,is substantially reduced by 10.2%.On the basis,KP505 propellers are further used for self-propelled simulation of the three optimized ship types and original ship types generated during the optimization process.The result shows that although the resistance increased slightly,the optimized ship type with significantly reduced wake non-uniformity had better propulsion efficiency,with a maximum improvement of 1.08%compared to the original ship type.