scholarly journals EXPERIMENTAL AND NUMERICAL INVESTIGATION ON MANEUVERING PERFORMANCE OF SMALL WATERPLANE AREA TWIN HULL

Brodogradnja ◽  
2021 ◽  
Vol 72 (2) ◽  
pp. 93-114
Author(s):  
Kun Dai ◽  
◽  
Yunbo Li ◽  
Keyword(s):  
Degrees Of Freedom ◽  
Model Tests ◽  
Navier Stokes ◽  
Modeling Group ◽  
Hydrodynamic Derivatives ◽  
Captive Model Tests ◽  
Mmg Model ◽  
Calm Water ◽  
Free Running ◽  
Convergence Study

Free running model tests and a system-based method are employed to evaluate maneuvering performance for a Small Waterplane Area Twin Hull (SWATH) ship in this paper. A 3 degrees of freedom Maneuvering Modeling Group (MMG) model is implemented to numerically simulate the maneuvering motions in calm water. Virtual captive model tests are performed by using a Reynolds-averaged Navier-Stokes (RANS) method to acquire hydrodynamic derivatives, after a convergence study to check the numerical accuracy. The turning and zigzag maneuvers are simulated by solving the maneuvering motion model and the predicted results agree well with the experimental data. Moreover, free running model tests are carried out for three lateral separations and the influence of the lateral separations on maneuvering performance is investigated. The research results of this paper will be helpful for the maneuvering prediction of the small waterplane area twin hull ship.

scholarly journals Numerical Estimation of Hull Hydrodynamic Derivatives in Ship Maneuvering Prediction

2021 ◽  
Vol 28 (2) ◽  
pp. 46-53
Author(s):  
Radosław Kołodziej ◽  
Paweł Hoffmann
Keyword(s):  
Model Tests ◽  
Circular Motion ◽  
Computational Method ◽  
Design Stage ◽  
Hydrodynamic Characteristics ◽  
Ship Maneuvering ◽  
Hydrodynamic Derivatives ◽  
Captive Model Tests ◽  
Ship Maneuverability ◽  
Free Running

Abstract Prediction of the maneuvering characteristics of a ship at the design stage can be done by means of model tests, computational simulations or a combination of both. The model tests can be realized as a direct simulation of the standard maneuvers with the free running model, which gives the most accurate results but is also the least affordable, as it requires a very large tank or natural lake, as well as the complex equipment of the model. Alternatively, a captive model test can be used to identify the hydrodynamic characteristics of the hull, which can be used to simulate the standard maneuvers with the use of dedicated software. Two types of captive model tests are distinguished: circular motion tests (CMT) and planar motion mechanism tests (PMM). The paper presents an attempt to develop a computational method for ship maneuverability prediction in which the hydrodynamic characteristics of the hull are identified by means of computational fluid dynamics (CFD). The CFD analyses presented here directly simulate the circular motion test. The resulting hull characteristics are verified against the available literature data, and the results of the simulations are verified against the results of free running model tests. Reasonable agreement shows the large potential of the proposed method.

scholarly journals Manoeuvring Prediction of KVLCC2 with Hydrodynamic Derivatives Generated by a Virtual Captive Model Test

2019 ◽  
Vol 26 (4) ◽  
pp. 16-26
Author(s):  
Kun Dai ◽  
Yunbo Li
Keyword(s):  
Model Test ◽  
Numerical Accuracy ◽  
Hydrodynamic Derivatives ◽  
Captive Model Tests ◽  
Mmg Model ◽  
Towing Tank Test ◽  
Tank Test ◽  
Convergence Study ◽  
Captive Model Test ◽  
Good Agreement

Abstract This paper describes the application of computational fluid dynamics rather than a towing tank test for the prediction of hydrodynamic derivatives using a RANS-based solver. Virtual captive model tests are conducted, including an oblique towing test and circular motion test for a bare model scale KVLCC2 hull, to obtain linear and nonlinear hydrodynamic derivatives in the 3rd-order MMG model. A static drift test is used in a convergence study to verify the numerical accuracy. The computed hydrodynamic forces and derivatives are compared with the available captive model test data, showing good agreement overall. Simulations of standard turning and zigzag manoeuvres are carried out with the computed hydrodynamic derivatives and are compared with available experimental data. The results show an acceptable level of prediction accuracy, indicating that the proposed method is capable of predicting manoeuvring motions.

Model Tests of a Caisson in Wet Towing for Assessing Resistance and Stability in Calm Water and Waves

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Chang-Wook Park ◽  
Jeonghwa Seo ◽  
Shin Hyung Rhee
Keyword(s):  
Degrees Of Freedom ◽  
Model Tests ◽  
Added Resistance ◽  
Power Requirement ◽  
Effective Power ◽  
Six Degrees Of Freedom ◽  
Calm Water ◽  
Improved Stability ◽  
Scale Ratio ◽  
The Stability

A series of model tests of a caisson in wet towing were conducted in a towing tank to assess the stability and effective power requirement in calm water and head sea conditions. The scale ratio of the model was 1/30, and the model-length-based Froude number in the tests ranged from 0.061 to 0.122, which is equivalent to 2 and 4 knots in the full scale, respectively. During the towing of the model, tension on the towline and six-degrees-of-freedom (6DOF) motion of the model were measured. Under the calm water condition, the effects of towing speed, draft, and initial trim variation on the towing stability and effective power were investigated. Initial trim improved stability and reduced required towing power. In head seas, effective power and towing stability were changed with the wavelength. It increased as the wavelength became longer, but the added resistance in long waves also stabilized the model with reduced yaw motion.

Hybrid Method for Predicting Ship Manoeuvrability in Regular Waves

2019 ◽  
Author(s):  
Tianlong Mei ◽  
Yi Liu ◽  
Manasés Tello Ruiz ◽  
Marc Vantorre ◽  
Evert Lataire ◽  
...  
Keyword(s):  
Experimental Data ◽  
Hybrid Method ◽  
Potential Flow ◽  
Flow Theory ◽  
Regular Waves ◽  
Potential Flow Theory ◽  
Hydrodynamic Derivatives ◽  
Mmg Model ◽  
Calm Water ◽  
Wave Induced

Abstract The ship’s manoeuvring behaviour in waves is significantly different from that in calm water. In this context, the present work uses a hybrid method combining potential flow theory and Computational Fluid Dynamics (CFD) techniques for the prediction of ship manoeuvrability in regular waves. The mean wave-induced drift forces are calculated by adopting a time domain 3D higher-order Rankine panel method, which includes the effect of the lateral speed and forward speed. The hull-related hydrodynamic derivatives are determined based on a RANS solver using the double body flow model. The two-time scale method is applied to integrate the improved seakeeping model in a 3-DOF modular type Manoeuvring Modelling Group (MMG model) to investigate the ship’s manoeuvrability in regular waves. Numerical simulations are carried out to predict the turning circle in regular waves for the S175 container carrier. The turning circle’s main characteristics as well as the wave-induced motions are evaluated. A good agreement is obtained by comparing the numerical results with experimental data obtained from existing literature. This demonstrates that combining potential flow theory with CFD techniques can be used efficiently for predicting the manoeuvring behaviour in waves. This is even more true when the manoeuvring derivatives cannot be obtained from model tests when there is lack of such experimental data.

Numerical Calculation of Added Mass for Ship Dynamic Stability by High Order Panel Method

2011 ◽  
Vol 97-98 ◽  
pp. 802-805
Author(s):  
Hua Ming Wang ◽  
Han Xing Zhao ◽  
Yu Long Yang ◽  
Xiao Song Rui
Keyword(s):  
Dynamic Stability ◽  
Three Dimensional ◽  
Added Mass ◽  
Model Tests ◽  
Panel Method ◽  
Design Stage ◽  
Captive Model Tests ◽  
Ship Maneuverability ◽  
Wigley Hull ◽  
Free Running

IMO Standards for ship maneuverability require prediction of ship’s maneuvering performance at the design stage. For this purpose, various methods such as those based on free running model tests, captive model tests or numerical simulation using mathematical models can be used. While this paper describes a numerical method for estimating ship’s dynamic stability by computing the linear sway and yaw added mass coefficients using a higher-order panel method based on Non-Uniform Rational B-Spline. Three dimensional forward-speed radiation problems are formulated and solved in frequency domain. The linear hydrodynamic coefficients are calculated and preliminary results are presented for a modified Wigley hull.

Simulating the Acceleration to Take-Off Phase of a WIG-Craft Using Results of a Constrained Experiment

2020 ◽  
Author(s):  
Ombor Pereowei Garrick ◽  
Zhiqiang Hu ◽  
Lei Song
Keyword(s):  
Simulation Model ◽  
High Speed ◽  
Model Tests ◽  
Constant Speed ◽  
Develop Model ◽  
State Variables ◽  
Acceleration Phase ◽  
Power Requirement ◽  
Captive Model Tests ◽  
Calm Water

Abstract The acceleration to take-off (in calm water and rough seas) is a short duration but very important motion regime of a WIG-craft. It determines the transport efficiency of a WIG-craft as a viable alternative to high speed marine vehicles or low speed aircrafts used in conveying workers to and offshore oil and gas fields. The development of a simulation model based on results from constant speed captive model tests for a WIG boat is imperative, when in the absence of appropriate experimental test rig, there is the need to investigate the attitude of the WIG-craft during its acceleration phase. Theoretical tools for investigating the characteristics of the acceleration phase of a WIG boat are uncommon and where they exist, they are almost unreliable, not been experimentally validated. Moreover, the cost associated with conducting acceleration tests is huge. The test facilities are not readily available in most maritime engineering research institutions. This study is concerned with the development of a simulation model with input from results of captive model tests to investigate the running attitude, forces and moments acting on a WIG-boat accelerating to take-off in calm water. A constrained model tests at constant speed levels were conducted for a range of model draughts and trim angles. Multivariate multiple regression method was used to develop model equations that fits the measured aero-hydro dynamic lift, drag and moment data as a function of draught, speed and trim angle. The hydrostatic and aero-hydrodynamic steady state forces and moments where combined into a state-space form which are solved in MATLAB. The state variables and the first and second derivatives of the states of the boat as well as the forces and moments acting on it are generated as output from the simulation model. Though the simulation model proved successful in predicting the attitude of the WIG-boat including crashing and excessive acceleration and power requirement during take-off, the results from the model still need to be verified with CFD analysis, a full WIG-boat trial tests or with the expensive high speed towing tank capable of carrying out acceleration runs. The method has the potential to be improved to account for the unsteady forces and moments that exists when the WIG-boat accelerates from offshore environment.

Numerical Simulation on Oblique Towing Tests and Pure Yaw Tests of a Containership in Surf-Riding Condition

2020 ◽  
Author(s):  
Chengqian Ma ◽  
Ning Ma ◽  
Xiechong Gu
Keyword(s):  
Mathematical Model ◽  
Critical Issue ◽  
Wave Effect ◽  
Hydrodynamic Derivatives ◽  
Course Stability ◽  
Mmg Model ◽  
Calm Water ◽  
Maneuvering In Waves ◽  
Surf Riding ◽  
Maneuvering Forces

Abstract Maneuvering in waves is a complex and critical issue that confuses researchers for the last several decades. Among the existing methods for predicting the maneuverability in waves, the widely-used mathematical model approach (MMG model) is considered to be efficient and accurate in large wavelength and small wave steepness conditions. However, based on the assumption that the maneuvering forces in waves are the same as those in calm water, the wave effect on the hydrodynamic derivatives is neglected in most mathematical model approaches. According to the previous theoretical analysis and experimental data, this assumption is flawed. Therefore, several experiments and some numerical simulations have conducted to research the wave effect on hydrodynamic derivatives. In the present study, oblique towing tests and pure yaw tests will be simulated using the state-of-the-art CFD techniques to obtain the linear hydrodynamic derivatives in waves. The simulation cases in the present study are set according to previous PMM tests of S175 containership in surf-riding conditions. And the simulation results are in good agreement with experimental ones. Based on that, the wave effect on hydrodynamic derivatives is obtained and some discussions are made. Finally, the course stability of the containership on the different relative position of the wave are calculated to analyze the preliminary reason for the broaching-to phenomenon.

CFD Simulations of Lifeboat During Sailing Phase in Harsh Weather

2015 ◽  
Author(s):  
Vidar Tregde ◽  
Sverre Steen
Keyword(s):  
Degrees Of Freedom ◽  
Free Fall ◽  
Model Tests ◽  
Full Scale ◽  
Cfd Simulations ◽  
Thrust Coefficient ◽  
Cfd Models ◽  
Calm Water ◽  
Set Up ◽  
Full Scale Tests

A free fall lifeboat is going through several phases during a drop; sliding on the skid, rotation on skid, free fall, water entry, ventilation, maximum submergence, resurfacing and the sailing phase. In the sailing phase, the engine is running, providing propeller thrust, and the vessel is exposed to wind and waves while trying to run away from the host. CFD simulations of the lifeboat in the sailing phase have been run in regular Stokes 5th order waves, as well as simulations in irregular seas. The regular waves have been set up with different wave heights and wave periods. The set-up of waves have been done to fulfil the requirements in DNV-OS-E406, which is the DNV-GL offshore standard for design of free fall lifeboats. Validation of the CFD models are done with comparison to model tests from calm water tests as well as self-propelled model tests in waves. Results from full scale tests in calm water and in waves are also used in validation of CFD results. The hydrodynamic problem solved for 3 degrees-of-freedom (DOF) free running model in waves with thrust force from propeller is solved using the CFD software Star CCM+. A method for estimating thrust coefficient with a combination of full scale calm water results and results from CFD simulations is presented. The CFD simulations have shown to give acceptable accuracy for lifeboat in a seaway. Further, the CFD simulations have shown to be very useful for demonstrating fulfilment of requirements in the offshore standard for lifeboats in the sailing phase.

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