Estimation method for life-cycle fuel consumption of merchant ships

近年来，对船舶全生命周期油耗进行严格预测，对于评估船舶全生命周期价值的重要性日益得到人们的重视。从船舶设计的角度来看，建立可靠的方法作为设计分析工具来准确预测船舶在实际波浪环境中的性能是至关重要的。为了实现这一目标，本研究提出了一种基于CFD船舶运动模拟的船舶性能预测方法。这是为了建立LC燃料消耗的评价方法。介绍了两个版本的CFD船舶运动模拟代码WISDAM-X和WISDAM-XI，并给出了一些应用实例。由于在重叠网格系统（WISDAM-X）或多块网格系统（WISDAM-XI）框架下，运动船体表面上的非线性自由面和体面条件都得到了精确满足，因此这两种代码都可以处理任意波浪条件下的任意船舶运动。WISDAM-X规范特别用于常规型船舶的设计。仿真结果表明，在较宽的波浪条件下，计算得到的弓形部分表面压力与实测数据吻合较好。在斜波中的模拟说明了非定常自由面激波的形成对附加阻力起着重要的作用。WISDAM-XI代码用于多体船舶的水动力性能预测。采用CFD计算程序对单体、双体船和三体船的阻力和耐波性能进行了估算，并与实验结果进行了对比验证。

In recent years, the importance has been recognizing for the rigorous predictions of life-cycle (LC) fuel consumption of ships to evaluate the life-cycle value (LCV) of ships. From a ship design point of view, it is of crucial importance to establish reliable methods for the accurate prediction of ship performance in the realistic wave environment as a design analysis tool. To achieve this objective, a new prediction procedure based on CFD ship motion simulation is developed for predicting ship performance in a seaway in the present study. This has been intended for the establishment of the evaluation method of LC fuel consumption.Two versions of the CFD ship-motion simulation code named WISDAM-X and WISDAM-XI are described with a number of application examples. Since the non-linear free-surface and body-surface conditions are satisfied exactly on the moving ship body surface in the framework of overlapping grid system (WISDAM-X) or multi-block grid system (WISDAM-XI), both codes cope with arbitrary ship motions in arbitrary wave conditions. The WISDAM-X code is especially used for the design of conventional type ships. The simulation results demonstrate that the computed pressure on the surface of the bow-part shows fairly good agreement with the measured data in a wide range of wave conditions. The simulations of the cases in the oblique waves elucidate the formation of unsteady free-surface- shock-wave which plays an important role for the added resistance. The WISDAM-XI code is used for the prediction of hydrodynamic performance of multihull vessels. Resistance and seakeeping performance of monohull, catamaran and trimaran vessels is estimated by the CFD code and they are validated through comparison with experiments.