At present, more and more offshore wind farms have been built anti ntnnerous projects are on the drawing tables. Therefore, the study on the safety of collision between ships and offshore wind turbines （OWT） is of g...At present, more and more offshore wind farms have been built anti ntnnerous projects are on the drawing tables. Therefore, the study on the safety of collision between ships and offshore wind turbines （OWT） is of great practical signifieance. The present study takes the advantage of the famous LS-DYNA explicit code to simulate the dynamic proeess of the collision between a typical 3MW offshore wind turbine model with monopile fi）undation and a simplified 2000t-class ship model. In the simulation, the added mass effect of the ship, contact nonlinearity of collision, material nonlinearity of steel and aluminum foam and adaptive mesh tectmique for large structure deformation have been taken into considera- tion. Proposed is a crashworthy device for OWF of new conceptual steel sphere shell-cireular ring aluminum foam pad, and the good pe.rfurmanee of the device under the conditions of ship-OWT front impact and side impact has been verified from the views of theoretical analysis and numerical results. The new crashworthy device can effectively smooth the contact force and reduce the top structure dynamic response, using its own structure plastic deformation to absorb most of the ship collision enerty. As a result, the main structure of the OWF and the inside key electric control equipments can be saved by scarifying the structural plastic deformation of new sphere crashworthy device. What is more, the sphere configuratiun design of the crashworthy device can effectively guide the ship to run away from the main OWT structure and reduce the damage of the ship and OWT to some degree during side impact.展开更多
This paper discusses mathematical modeling of a ship equipped with energy-saving wing devices.Therewith,the ship is mathematically represented by an elongated hull with high-aspect-ratio wings mounted near its bow and...This paper discusses mathematical modeling of a ship equipped with energy-saving wing devices.Therewith,the ship is mathematically represented by an elongated hull with high-aspect-ratio wings mounted near its bow and stern.Equations,describing ship motions in regular oncoming waves,are written in the spirit of strip theory with account of inertial and damping influence of energy-saving wing elements with the use of linear expansion of wing-related forces with respect to heave and pitch perturbations.This approach readily yields fast numerical solutions for the propulsion of a ship with wings in waves.The latter solutions are then used as an input for calculation of thrust on wing elements on the basis of classical unsteady foil theories corrected for finite aspect ratio.To evaluate speed of the ship in the modes which allow cruising exclusively by wave power,it is hypothetically assumed that in this case,the wave-generated thrust on the wings equals total drag of the ship-plus-wings system,the latter being defined as a sum of its viscous,wave-making,induced(for wing elements)and added-wave components.Excepting the added-wave term and wings’contributions,the total drag is calculated herein by Holtrop method whereas added-wave resistance is evaluated with Beukelman-Gerritsma formula involving kinematic parameters of heaving and pitching motions of the ship calculated both without and with account of the wings.Also discussed in the paper is a decrease of added wave resistance for a ship with wings as compared to that of ship without wings.Finally,the energy efficiency design index(EEDI)introduced by the International Maritime Organization(IMO)is discussed for representative sea conditions as a measure of ship environmental friendliness.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.50538020)the National Science and Technology Planning(Grant No.2006BAJ03B00)
文摘At present, more and more offshore wind farms have been built anti ntnnerous projects are on the drawing tables. Therefore, the study on the safety of collision between ships and offshore wind turbines （OWT） is of great practical signifieance. The present study takes the advantage of the famous LS-DYNA explicit code to simulate the dynamic proeess of the collision between a typical 3MW offshore wind turbine model with monopile fi）undation and a simplified 2000t-class ship model. In the simulation, the added mass effect of the ship, contact nonlinearity of collision, material nonlinearity of steel and aluminum foam and adaptive mesh tectmique for large structure deformation have been taken into considera- tion. Proposed is a crashworthy device for OWF of new conceptual steel sphere shell-cireular ring aluminum foam pad, and the good pe.rfurmanee of the device under the conditions of ship-OWT front impact and side impact has been verified from the views of theoretical analysis and numerical results. The new crashworthy device can effectively smooth the contact force and reduce the top structure dynamic response, using its own structure plastic deformation to absorb most of the ship collision enerty. As a result, the main structure of the OWF and the inside key electric control equipments can be saved by scarifying the structural plastic deformation of new sphere crashworthy device. What is more, the sphere configuratiun design of the crashworthy device can effectively guide the ship to run away from the main OWT structure and reduce the damage of the ship and OWT to some degree during side impact.
基金the Ministry of Science and Higher Education of the Russian Federation as part of World-class Research Center program:Advanced Digital Technologies(contract No.075–15–2020–903 dated 16.11.2020).
文摘This paper discusses mathematical modeling of a ship equipped with energy-saving wing devices.Therewith,the ship is mathematically represented by an elongated hull with high-aspect-ratio wings mounted near its bow and stern.Equations,describing ship motions in regular oncoming waves,are written in the spirit of strip theory with account of inertial and damping influence of energy-saving wing elements with the use of linear expansion of wing-related forces with respect to heave and pitch perturbations.This approach readily yields fast numerical solutions for the propulsion of a ship with wings in waves.The latter solutions are then used as an input for calculation of thrust on wing elements on the basis of classical unsteady foil theories corrected for finite aspect ratio.To evaluate speed of the ship in the modes which allow cruising exclusively by wave power,it is hypothetically assumed that in this case,the wave-generated thrust on the wings equals total drag of the ship-plus-wings system,the latter being defined as a sum of its viscous,wave-making,induced(for wing elements)and added-wave components.Excepting the added-wave term and wings’contributions,the total drag is calculated herein by Holtrop method whereas added-wave resistance is evaluated with Beukelman-Gerritsma formula involving kinematic parameters of heaving and pitching motions of the ship calculated both without and with account of the wings.Also discussed in the paper is a decrease of added wave resistance for a ship with wings as compared to that of ship without wings.Finally,the energy efficiency design index(EEDI)introduced by the International Maritime Organization(IMO)is discussed for representative sea conditions as a measure of ship environmental friendliness.
