The seakeeping performance of a luxury cruise ship was evaluated during the concept design phase.By comparing numerical predictions based on 3-D linear potential flow theory in the frequency domain with the results of...The seakeeping performance of a luxury cruise ship was evaluated during the concept design phase.By comparing numerical predictions based on 3-D linear potential flow theory in the frequency domain with the results of model tests, it was shown that the 3-D method predicted the seakeeping performance of the luxury cruise ship well.Based on the model, the seakeeping features of the luxury cruise ship were analyzed, and then the influence was seen of changes to the primary design parameters (center of gravity, inertial radius, etc.).Based on the results, suggestions were proposed to improve the choice of parameters for luxury cruise ships during the concept design phase.They should improve seakeeping performance.展开更多
Ocean waves are the core environmental elements affecting the movements and structure design of ships. Statistical analysis of wave parameters is the basis for the establishment of long-term ship environmental adaptab...Ocean waves are the core environmental elements affecting the movements and structure design of ships. Statistical analysis of wave parameters is the basis for the establishment of long-term ship environmental adaptability prediction model. The observations from coastal stations, buoys, altimeters and volunteer ships that cover from 1993 to 2011 were interpolated into miller Ion-lat grids by using bilinear method and the analytical fields of ocean waves were given. By using optimal interpolation, the analysis wave fields were assimilated into the WAVEWATCH III （WW3） simulation results. From the assimilated results, the wave rose statistics, the wave height of muitiyear return period and the extreme 2-D wave spectrum are related to the ship seakeeping were calculated. Finally, the wave statistics in China offshore were analyzed in detail.展开更多
The hydrodynamic analysis of a new semi-small waterplane area twin hull （SWATH） suitable for various applications such as small and medium size passenger ferries is presented. This may be an attractive crossover con...The hydrodynamic analysis of a new semi-small waterplane area twin hull （SWATH） suitable for various applications such as small and medium size passenger ferries is presented. This may be an attractive crossover configuration resulting from the merging of two classical shapes： a conventional SWATH and a fast catamaran. The final hull design exhibits a wedge-like waterline shape with the maximum beam at the stem; the hull ends with a very narrow entrance angle, has a prominent bulbous bow typical of SWATH vessels, and features full stern to arrange waterjet propellers. Our analysis aims to perform a preliminary assessment of the hydrodynamic performance of a hull with such a complex shape both in terms of resistance of the hull in calm water and seakeeping capability in regular head waves and compare the performance with that of a conventional SWATH. The analysis is performed using a boundary element method that was preliminarily validated on a conventional SWATH vessel.展开更多
The effect of coupling between sloshing and ship motions in the evaluation of slosh-induced interior pressures is studied. The coupling between sloshing loads and ship motions is modelled through a hybrid algorithm wh...The effect of coupling between sloshing and ship motions in the evaluation of slosh-induced interior pressures is studied. The coupling between sloshing loads and ship motions is modelled through a hybrid algorithm which combines a potential flow solution based on transient Green function for the external ship hydrodynamics with a viscous flow solution based on a multiphase interface capturing volume of fluid(VOF) technique for the interior sloshing motion. The coupled algorithm accounts for full nonlinear slosh forces while the external forces on the hull are determined through a blended scheme of linear radiationdiffraction with nonlinear Froude-Krylov and restoring forces. Consideration of this level of nonlinearities in ship motions is found to have non-negligible effects on the slosh-coupled responses and slosh-induced loads. A scheme is devised to evaluate the statistical measure of the pressures through long-duration simulation studies in extreme irregular waves. It is found that coupling significantly influences the tank interior pressures, and the differences in the pressures between coupled and uncoupled cases can be as much as 100% or more. To determine the RAO over the frequency range needed for the simulation studies in irregular waves, two alternative schemes are proposed, both of which require far less computational time compared to the conventional method of finding RAO at each frequency, and the merits of these are discussed.展开更多
Experiment was carried out to investigate the effects of wave direction and rolling motion on deck wetness and relative motion for a large fast container ship. The experimental results of the regular and irregular wav...Experiment was carried out to investigate the effects of wave direction and rolling motion on deck wetness and relative motion for a large fast container ship. The experimental results of the regular and irregular waves were presented. It is concluded that the wave directions and rolling motion have a considerable influence on the relative motion at mid-ship.展开更多
The impulse response method is a frequently used method to calculate ship seakeeping behavior.In this paper,the restoring and Froude-Krylov calculation is conducted with constant evaluation of panel pressures as well ...The impulse response method is a frequently used method to calculate ship seakeeping behavior.In this paper,the restoring and Froude-Krylov calculation is conducted with constant evaluation of panel pressures as well as Gauss quadrature and an analytical integration.The applied panel grid is coarsened by an adaptive algorithm which is based on a normal vector condition.The comparison of methods is based on grid convergence studies which are followed by a verification of forces with computational fluid dynamics(CFD)results on the fixed duisburg test case in waves.Validations with experimental results in head,oblique and following waves show that all integration methods are accurate.The exact integration is numerically sensitive in some cases.Gauss quadrature is highly accurate;however,the additional effort is not beneficial since the geometrical accuracy has-stronger influence on the force amplitudes than the integration method.Adaptive grid coarsening reduces the simulation time and is accurate up to a level,where the panel length comes close the wavelength.The added resistance at the investigated Froude number of 0.05 shows higher uncertainty levels,this applies to the results of both the numerical methods and model tests.展开更多
文摘The seakeeping performance of a luxury cruise ship was evaluated during the concept design phase.By comparing numerical predictions based on 3-D linear potential flow theory in the frequency domain with the results of model tests, it was shown that the 3-D method predicted the seakeeping performance of the luxury cruise ship well.Based on the model, the seakeeping features of the luxury cruise ship were analyzed, and then the influence was seen of changes to the primary design parameters (center of gravity, inertial radius, etc.).Based on the results, suggestions were proposed to improve the choice of parameters for luxury cruise ships during the concept design phase.They should improve seakeeping performance.
基金supports from National Natural Science Foundation of China (No. 41406032 and No. 41376014)Open Fund of State Key Laboratory of Satellite Ocean Environment Dynamics (No. SOED1305)
文摘Ocean waves are the core environmental elements affecting the movements and structure design of ships. Statistical analysis of wave parameters is the basis for the establishment of long-term ship environmental adaptability prediction model. The observations from coastal stations, buoys, altimeters and volunteer ships that cover from 1993 to 2011 were interpolated into miller Ion-lat grids by using bilinear method and the analytical fields of ocean waves were given. By using optimal interpolation, the analysis wave fields were assimilated into the WAVEWATCH III （WW3） simulation results. From the assimilated results, the wave rose statistics, the wave height of muitiyear return period and the extreme 2-D wave spectrum are related to the ship seakeeping were calculated. Finally, the wave statistics in China offshore were analyzed in detail.
文摘The hydrodynamic analysis of a new semi-small waterplane area twin hull （SWATH） suitable for various applications such as small and medium size passenger ferries is presented. This may be an attractive crossover configuration resulting from the merging of two classical shapes： a conventional SWATH and a fast catamaran. The final hull design exhibits a wedge-like waterline shape with the maximum beam at the stem; the hull ends with a very narrow entrance angle, has a prominent bulbous bow typical of SWATH vessels, and features full stern to arrange waterjet propellers. Our analysis aims to perform a preliminary assessment of the hydrodynamic performance of a hull with such a complex shape both in terms of resistance of the hull in calm water and seakeeping capability in regular head waves and compare the performance with that of a conventional SWATH. The analysis is performed using a boundary element method that was preliminarily validated on a conventional SWATH vessel.
文摘The effect of coupling between sloshing and ship motions in the evaluation of slosh-induced interior pressures is studied. The coupling between sloshing loads and ship motions is modelled through a hybrid algorithm which combines a potential flow solution based on transient Green function for the external ship hydrodynamics with a viscous flow solution based on a multiphase interface capturing volume of fluid(VOF) technique for the interior sloshing motion. The coupled algorithm accounts for full nonlinear slosh forces while the external forces on the hull are determined through a blended scheme of linear radiationdiffraction with nonlinear Froude-Krylov and restoring forces. Consideration of this level of nonlinearities in ship motions is found to have non-negligible effects on the slosh-coupled responses and slosh-induced loads. A scheme is devised to evaluate the statistical measure of the pressures through long-duration simulation studies in extreme irregular waves. It is found that coupling significantly influences the tank interior pressures, and the differences in the pressures between coupled and uncoupled cases can be as much as 100% or more. To determine the RAO over the frequency range needed for the simulation studies in irregular waves, two alternative schemes are proposed, both of which require far less computational time compared to the conventional method of finding RAO at each frequency, and the merits of these are discussed.
文摘Experiment was carried out to investigate the effects of wave direction and rolling motion on deck wetness and relative motion for a large fast container ship. The experimental results of the regular and irregular waves were presented. It is concluded that the wave directions and rolling motion have a considerable influence on the relative motion at mid-ship.
文摘The impulse response method is a frequently used method to calculate ship seakeeping behavior.In this paper,the restoring and Froude-Krylov calculation is conducted with constant evaluation of panel pressures as well as Gauss quadrature and an analytical integration.The applied panel grid is coarsened by an adaptive algorithm which is based on a normal vector condition.The comparison of methods is based on grid convergence studies which are followed by a verification of forces with computational fluid dynamics(CFD)results on the fixed duisburg test case in waves.Validations with experimental results in head,oblique and following waves show that all integration methods are accurate.The exact integration is numerically sensitive in some cases.Gauss quadrature is highly accurate;however,the additional effort is not beneficial since the geometrical accuracy has-stronger influence on the force amplitudes than the integration method.Adaptive grid coarsening reduces the simulation time and is accurate up to a level,where the panel length comes close the wavelength.The added resistance at the investigated Froude number of 0.05 shows higher uncertainty levels,this applies to the results of both the numerical methods and model tests.
