Design Approach for Reducing the Wave Added Resistance by Hull Form Optimisation

2019 ◽  
pp. 385-400
Author(s):  
M. Kumar Sanchana ◽  
R. Vijayakumar ◽  
V. V. S. Prasad
Keyword(s):  
Design Approach ◽  
Added Resistance ◽  
Hull Form

The Performance of Sailing Yachts in Oblique Seas

1974 ◽  
Vol 11 (04) ◽  
pp. 383-392
Author(s):  
David R. Pedrick
Keyword(s):  
Wave Length ◽  
Added Resistance ◽  
Regular Waves ◽  
Sea State ◽  
Hull Form ◽  
Rough Water ◽  
Rational Procedure ◽  
The Difference ◽  
Relationship Of ◽  
The Relationship

The difference in the effects of rough water on similar sailing yachts has been one of the intriguing puzzles that sailors, designers, and researchers have long tried to understand. It is not uncommon for two yachts of equal performance in smooth-sea conditions to have their speed or pointing ability reduced by different amounts when encountering waves. To investigate the causes of such behavior, it is important to have a rational procedure to analyze how changes in hull form, weight distribution, rig, and other design features affect the speed and motions of sailing yachts. This paper discusses the relationship of wind to rough water and of motions and added resistance to wave length and height. It then describes a procedure to predict motions, sailing speed, and speed-made-good to windward in realistic windward sailing conditions. The procedure utilizes results of heeled and yawed model tests of 12-metre yachts in oblique regular waves to predict performance in a Pierson-Moskowitz sea state corresponding closely to the equilibrium true wind speed.

A Numerical Study on Correlation Between the Bow Design Parameters and Added Resistance Using the Design of Experiments

2016 ◽  
Author(s):  
Gwan Hoon Kim ◽  
Hyun Joon Shin ◽  
Jeonghwa Seo ◽  
Shin Hyung Rhee
Keyword(s):  
Design Of Experiments ◽  
Numerical Simulations ◽  
Numerical Study ◽  
Design Parameters ◽  
Added Resistance ◽  
Hull Form ◽  
Entrance Angle ◽  
Wave Condition ◽  
Added Resistance In Waves ◽  
Bulbous Bow

In this study, numerical computation was carried out for evaluating the effects of the design parameter variations on the added resistance of Aframax tanker in head seas. The design of experiments (DOE) was used to efficiently conduct the numerical simulations with the hull form variations and save computational resources. A computational fluid dynamics (CFD) code based on the continuity and Reynolds averaged Navier-Stokes (RANS) equation was used for the numerical simulation. The simulation was performed in a short wave condition where the wave length was half of the ship length, which is expected to be most frequent in the vessel operation. Five design parameters of fore-body hull form were selected for the variations: design waterline length (DWL), bulbous bow height (BBH), bulbous bow volume (BBV), bow flare angle (BFA) and bow entrance angle (BEA). Each parameter had two levels in the variations, thus total 32 cases were designed initially. The results of the numerical simulations were analyzed statistically to determine the main effects and correlations in the five design parameters variations. Among them, the most significant parameter that influences on the added resistance in waves was DWL, followed by BBV and BEA. The other parameters had little effects on the added resistance in waves. By the computations, it was revealed that Extending DWL and decreasing BEA promoted the reflection of waves more toward the side than forward. In addition, there existed two-way interactions for the following two-factor combinations: DWL-BFA, DWL-BEA, DWL-BBV, BBH-BBV.

A Multi-Level Approach to the Prediction of the Added Resistance and Powering of Ships in Waves

2019 ◽  
Author(s):  
Shukui Liu ◽  
Apostolos Papanikolaou ◽  
Peiyuan Feng ◽  
Sheming Fan
Keyword(s):  
Asymptotic Formula ◽  
Empirical Formula ◽  
Ship Design ◽  
Level Of Detail ◽  
Added Resistance ◽  
Hull Form ◽  
Computational Tools ◽  
Multi Level ◽  
Design Software ◽  
Semi Empirical

Abstract In this paper, we present a multi-level fidelity approach and associated computational tools for the prediction of the added resistance of various types of ships in waves. Employed methods include a fully empirical formula, a semi-empirical asymptotic formula, a potential flow, 3D panel method and a CFD code. Each of them requires a different level of detail for the hull form and this enables the application to various practical scenarios. The developed software tools are here validated against recently obtained model experiments data from MARIC. Developed tools are now integrated in the design software platform of MARIC and are used in the optimisation of ship design.

Numerical Analysis of the Influence of Above-Water Bow Form on Added Resistance Using Nonlinear Slender Body Theory

2005 ◽  
Vol 49 (03) ◽  
pp. 191-206
Author(s):  
Hajime Kihara ◽  
Shigeru Naito ◽  
Makoto Sueyoshi
Keyword(s):  
Three Dimensional ◽  
Wave Force ◽  
Slender Body ◽  
Added Resistance ◽  
Slender Body Theory ◽  
Hull Form ◽  
Nonlinear Properties ◽  
Head Waves ◽  
The Time Domain ◽  
Body Theory

A nonlinear numerical method is presented for the prediction of the hydrodynamic forces that act on an oscillating ship with a forward speed in head waves. A "parabolic" approximation of equations called "2.5D" or "2D+T" theory was used in a three-dimensional ship wave problem, and the computation was carried out in the time domain. The nonlinear properties associated with the hydrostatic, hydrodynamic, and Froude-Krylov forces were taken into account in the framework of the slender body theory. This work is an extension of the previous work of Kihara and Naito (1998). The application of this approach to the unsteady wave-making problem of a ship with a real hull form is described. The focus is on the influence of the above-water hull form on the horizontal mean wave force. Comparison with experimental results demonstrates that the method is valid in predicting added resistance. Prediction of added resistance for blunt ships is also shown by example.

Sailing Yacht Performance in Calm Water and in Waves

1993 ◽  
Author(s):  
J. Gerritsma ◽  
J. A. Keuning ◽  
A. Versluis
Keyword(s):  
Model Experiment ◽  
Irregular Waves ◽  
Current Interest ◽  
Added Resistance ◽  
Hull Form ◽  
Wide Range ◽  
Calm Water ◽  
Added Resistance In Waves ◽  
Sailing Yacht ◽  
Calculated Analysis

The Delft systematic Yatch Hull Series has been extended to a total of 39 hull form variations, covering a wide range of length displacement ratios and other form of parameters. The total set of model experiment results, upright and heeled resistance as well as sideforce and stability, had been analysed and polynomial expressions to approximate these quantities are presented. In view of the current interest in the performance of sailing yachts in waves, the added resistance in irregular waves of 8 widely different hull variations has been calculated. Analysis of the results shows that the added resistance in waves strongly depends on the product of displacement-length ratio and the gyradius of the pitching motion.

scholarly journals Added Resistance in Waves and Amplitude Function Expressing a Ship Hull Form

2008 ◽  
Vol 8 (0) ◽  
pp. 163-169 ◽  
Author(s):  
Shigeru Naito ◽  
Mariko Kuroda ◽  
Hisahumi Yoshida ◽  
Takehiro Ikeda
Keyword(s):  
Ship Hull ◽  
Added Resistance ◽  
Amplitude Function ◽  
Hull Form ◽  
Added Resistance In Waves

scholarly journals Hull form optimization in the conceptual design stage considering operational efficiency in waves

2018 ◽  
Vol 233 (3) ◽  
pp. 745-759 ◽  
Author(s):  
Yoo-Won Jung ◽  
Yonghwan Kim
Keyword(s):  
Optimization Method ◽  
Operational Efficiency ◽  
Hydrodynamic Performance ◽  
Design Stage ◽  
Total Resistance ◽  
Added Resistance ◽  
Slender Body Theory ◽  
Hull Form ◽  
Weather Factor ◽  
Calm Water

This study focuses on the optimization of ship dimensions by considering hydrodynamic performance in waves. In actual seaways, a ship experiences speed loss due to environmental loads by waves and wind. Therefore, along with calm water resistance, speed loss in waves should be considered in the hull form design in order to improve operational efficiency in waves. However, a trade-off may be needed between total resistance on the ship and the speed loss in waves. To address this problem, Non-dominated Sorting Genetic Algorithm II, which is a multi-objective optimization method, is used to minimize the total resistance on a ship in seaways and the speed loss by additional resistance. In the optimization process, added resistance is predicted using a numerical method based on slender-body theory, Maruo’s far-field formulation, and an empirical formula for added resistance in short waves. The speed loss in waves, which can be expressed by a weather factor ( fw), is estimated using power–speed curves. This article introduces some examples of the sensitivity analysis of added resistance and speed loss in waves to the variations of ship dimensions. Finally, the optimization solutions on a Pareto front set are compared to a basis ship in terms of hull form, and the corresponding hydrodynamic performances are evaluated.

Experimental investigation on the added resistance of modified KVLCC2 hull forms with different bow shapes

2016 ◽  
Vol 231 (2) ◽  
pp. 395-410
Author(s):  
Jaehoon Lee ◽  
Dong-Min Park ◽  
Yonghwan Kim
Keyword(s):  
Model Tests ◽  
Green Water ◽  
Added Resistance ◽  
Hull Form ◽  
Motion Responses ◽  
Wide Range ◽  
Added Resistance In Waves ◽  
Design Speed ◽  
Hull Forms ◽  
Motion Amplitude

The effect of different bow shapes on the added resistance in waves was observed through a series of model tests. To this end, three different hull forms of KRISO Very Large Crude Carrier 2 were considered: an original hull form and two modified hulls with different bow shapes, called ax-bow and leadge-bow. The model tests were conducted for a wide range of wavelengths with two wave amplitudes in a regular head-sea condition at the design speed. Each test condition was imposed at least twice in order to check the repeatability of measurement, considering the uncertainties in model test and the nonlinear nature of the added resistance. This article introduces a preliminary study on the effects of surge motion, amplitude of incident wave, and green-water allowance around bow region. This article briefly includes the uncertainty analysis of recent study regarding the performance of the original hull. Based on the results of the experimental study for three different bow shapes, the parameters which influence the added resistance and motion responses are discussed.

scholarly journals Study on Hull Optimization Process Considering Operational Efficiency in Waves

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 898
Author(s):  
Beom-Soo Kim ◽  
Min-Jae Oh ◽  
Jae-Hoon Lee ◽  
Yong-hwan Kim ◽  
Myung-Il Roh
Keyword(s):  
Water Resistance ◽  
Operational Efficiency ◽  
Free Form ◽  
Total Resistance ◽  
Added Resistance ◽  
Deformation Method ◽  
Cross Sectional ◽  
Hull Form ◽  
Strip Theory ◽  
Calm Water

This study investigates the optimization of the hull form of a tanker, considering the operational efficiency in waves, in accordance with the recent Energy Efficiency Design Index regulation. For this purpose, the total resistance and speed loss of the ship under representative sea conditions were minimized simultaneously. The total resistance was divided into three components: calm water resistance, added resistance due to wind, and to waves. The first two components were calculated using regression formulas, and the last component was estimated using the strip theory, far-field method, and the short-wave correction formula. Next, prismatic coefficient, waterline length, waterplane area, and flare angle were selected as design variables from the perspective of operational efficiency. The hull form was described as a combination of cross-sectional curves. A combination of the method shifting these sections in the longitudinal direction and the Free-Form Deformation method was used to deform the hull. As a result of applying the non-dominated sorting genetic algorithm to a tanker, the hull was deformed thinner and longer, and it was determined that the total resistance and speed loss were reduced by 3.58 and 10.2%, respectively. In particular, the added resistance due to waves decreased significantly compared to the calm water resistance, which implies that the present tendency differs from conventional ship design that optimizes only the calm water resistance.

The Windward Performance of Yachts in Rough Water

1999 ◽  
Author(s):  
Jonathan Binns ◽  
Bruce McRae ◽  
Giles Thomas
Keyword(s):  
Research Program ◽  
Length Ratio ◽  
Added Resistance ◽  
Hull Form ◽  
Model Experiments ◽  
Theoretical Predictions ◽  
Rough Water

A 5 year research program to investigate the effect of realistic hull form parameters on the added resistance of a yacht in waves is nearing completion. Model experiments and theoretical predictions were carried out and the results are discussed in this paper. Five hull form parameters have been investigated so far, they are: 1. stem overhang; 2. LCB-LCF separation; 3. prismatic coefficient; 4. displacement length ratio and 5. beam draft ratio.

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