Assessment of CFD for KCS Added Resistance and for ONRT Course Keeping/Speed Loss in Regular Head and Oblique Waves

2020 ◽  
pp. 333-439
Author(s):  
Frederick Stern ◽  
Hamid Sadat-Hosseini ◽  
Timur Dogan ◽  
Matteo Diez ◽  
Dong Hwan Kim ◽  
...  
Keyword(s):  
Added Resistance ◽  
Oblique Waves

scholarly journals Added resistance and seakeeping performance of trimarans in oblique waves

2020 ◽  
Vol 216 ◽  
pp. 107721
Author(s):  
Jiaye Gong ◽  
Shiqiang Yan ◽  
Qingwei Ma ◽  
Yunbo Li
Keyword(s):  
Added Resistance ◽  
Oblique Waves ◽  
Seakeeping Performance

scholarly journals Comparative study on analysis methods for added resistance of four ships in head and oblique waves

2021 ◽  
Vol 236 ◽  
pp. 109552
Author(s):  
Jae-Hoon Lee ◽  
Yonghwan Kim ◽  
Beom-Soo Kim ◽  
Frederik Gerhardt
Keyword(s):  
Comparative Study ◽  
Added Resistance ◽  
Oblique Waves ◽  
Analysis Methods

A Novel Measure to Reduce Ship Resistance in Waves

2017 ◽  
Author(s):  
Bingjie Guo ◽  
Bjørn-Johan Vartdal ◽  
Sverre Steen
Keyword(s):  
Cfd Simulation ◽  
Low Cost ◽  
Ship Motions ◽  
The Novel ◽  
Added Resistance ◽  
Wave Condition ◽  
Oblique Waves ◽  
Ship Resistance ◽  
Added Resistance In Waves ◽  
3D Effect

Ships travel in waves most of the time. The horsepower increase or speed loss in waves can become large in adverse sea. Speed loss needs to be compensated for by increasing the power. Moreover, the associated speed-loss can possibly not be compensated due to the limit of installed power. This will cause delays, and may even lead to safety concerns in maneuvering. Thus, there is a need for minimizing added resistance due to both economical and safety reasons. Ships with better performance in waves even with reduced power are desired. Latest researches on advanced ship optimization are taking added resistance into account. Ship bow optimization has been the main measure to reduce added resistance in waves. Based on analyzing the working principles and potential benefit of the different kinds of novel ship bows, a novel measure is proposed to reduce the ship resistance in waves is proposed. A novel measure to reduce the ship resistance in waves of existing ships by installing a simple structure at the ship bow. The structure is designed to sharpen the ship bow and therefore reduce added resistance due to wave reflection. Thus, it is suitable for the large tankers and bulk carriers, which have blunt bows. The volume above free surface was expected to reduce ship motions and the added resistance due to ship motions consequently. This measure does not change the original ship design. It can be retrofitted on existing ships fairly easily at low cost. In order to verify the benefit due to the retrofitted structure, CFD simulations are performed in both head and oblique waves, which can take 3D effect into account. Four different retrofitted structures are designed and the numerical simulations are performed with the same numerical and mesh settings in each wave condition. The CFD simulation results confirm that the novel measure can reduce ship added resistance efficiently and it also has benefits in oblique waves.

Added Powering Measurements of KCS Maneuvering in Regular Variable Heading Waves

2017 ◽  
Author(s):  
Yugo Sanada ◽  
Shogo Ito ◽  
Yasuyuki Toda ◽  
Frederick Stern
Keyword(s):  
Scale Effects ◽  
Open Water ◽  
Container Ship ◽  
Added Resistance ◽  
Oblique Waves ◽  
Wave Basin ◽  
Head Waves ◽  
Regular Variable ◽  
Free Running ◽  
Thrust And Torque

To know more detail of added powering and propeller load fluctuations in regular waves during free-maneuvering, free-running tests of KRISO Container Ship model (KCS) are conducted. KCS 2.7 m model that was used in the previous surge-free added resistance experiments is modified and new free-running system with compact dynamometer is installed. Free-running tests in calm water and in regular variable heading waves are performed at IIHR 40 m × 20 m × 3 m wave basin to obtain 6DOF motions with thrust/torque data. Propeller open water tests were performed at Osaka University towing tank (OU). To evaluate facility bias and scale effects, trajectories, motions and maneuvering characteristic parameters are compared with those of different size model taken at other facilities. Free-running course keeping tests in regular variable heading waves are performed as same conditions with Tokyo 2015 A Workshop on CFD in Ship Hydrodynamics (T2015) case 2.10 and case 2.11. Those results are compared with the data taken at FORCE with 6 m free-running model and OU with 3.2 m model by surge-free mount. In head waves, trends of RAO for heave and pitch are the same under surge-free and free-running. Added thrust/torque and propeller open water efficiency reduction of IIHR and OU become maximum at λ/ L=1.15 where the added resistance was maximum under surge-free condition. In oblique waves, added thrust and torque become larger where the wave encounter angle is from 0° to 45° and both trends agree with other type of container ship. Thrust and torque fluctuations of KCS become larger in beam and following waves. Variation of self-propulsion factors due to wave encounter angles are small in oblique waves.

scholarly journals Calculation of Added Resistance in Oblique Waves

1980 ◽  
Vol 1980 (147) ◽  
pp. 79-84 ◽  
Author(s):  
Hajime Maruo ◽  
Kazuo Iwase
Keyword(s):  
Added Resistance ◽  
Oblique Waves

scholarly journals RANS Prediction of Wave-Induced Ship Motions, and Steady Wave Forces and Moments in Regular Waves

2021 ◽  
Vol 9 (12) ◽  
pp. 1459
Author(s):  
Qingze Gao ◽  
Lifei Song ◽  
Jianxi Yao
Keyword(s):  
Wave Amplitude ◽  
Ship Motions ◽  
Wave Forces ◽  
Inertial Effects ◽  
Added Resistance ◽  
Oblique Waves ◽  
Steady Wave ◽  
Head Waves ◽  
Wave Induced ◽  
Hydrodynamic Effects

The wave-induced motions, and steady wave forces and moments for the oil tanker KVLCC2 in regular head and oblique waves are numerically predicted by using the expanded RANS solver based on OpenFOAM. New modules of wave boundary condition are programed into OpenFOAM for this purpose. In the present consideration, the steady wave forces and moments include not only the contribution of hydrodynamic effects but also the contribution of the inertial effects due to wave-induced ship motions. The computed results show that the contribution of the inertial effects due to heave and pitch in head waves is non-negligible when wave-induced motions are of large amplitude, for example, in long waves. The influence of wave amplitude on added resistance in head waves is also analyzed. The dimensionless added resistance becomes smaller with the increasing wave amplitude, indicating that added resistance is not proportional to the square of wave amplitude. However, wave amplitude seems not to affect the heave and pitch RAOs significantly. The steady wave surge force, sway force and yaw moment for the KVLCC2 with zero speed in oblique waves are computed as well. The present RANS results are compared with available experimental data, and very good agreements are found between them.

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