Small water-plane area twin-hull（SWATH） has drawn the attention of many researchers due to its good sea-keeping ability.In this paper,MMG＇s idea of separation was used to perform SWATH movement modeling and simulat...Small water-plane area twin-hull（SWATH） has drawn the attention of many researchers due to its good sea-keeping ability.In this paper,MMG＇s idea of separation was used to perform SWATH movement modeling and simulation;respectively the forces and moment of SWATH were divided into bare hull,propeller,rudder at the fluid hydrodynamics,etc.Wake coefficient at the propellers which reduces thrust coefficient,and rudder mutual interference forces among the hull and propeller,for the calculation of SWATH,were all considered.The fourth-order Runge-Kutta method of integration was used by solving differential equations,in order to get SWATH＇s movement states.As an example,a turning test at full speed and full starboard rudder of ‘Seagull＇ craft is shown.The simulation results show the SWATH＇s regular pattern and trend of motion.It verifies the correctness of the mathematical model of the turning movement.The SWATH＇s mathematical model is applied to marine simulator in order to train the pilots or seamen,or safety assessment for ocean engineering project.Lastly,the full mission navigation simulating system（FMNSS） was determined to be a successful virtual reality technology application sample in the field of navigation simulation.展开更多
The effects of hydrostatic pressure, dissolved oxygen, temperature and flow velocity, and their interaction on the corrosion rates of E690 high-strength steel (HSS) in simulated marine environments were studied using ...The effects of hydrostatic pressure, dissolved oxygen, temperature and flow velocity, and their interaction on the corrosion rates of E690 high-strength steel (HSS) in simulated marine environments were studied using response surface methodology. The results show that the flow velocity exerts the most significant influence on the corrosion rate of E690 HSS. Consequently, the corrosion behavior of E690 HSS under varying flow velocities were analyzed profoundly from initial pitting corrosion to long-term corrosion properties. The results indicate that the flow state facilitates the mass transfer and enhances the adsorption tendency of Cl− by enhancing the electrochemical activity of the steel surface. These factors accelerate the electrochemical reactions, resulting in increased pitting density, depth and the long-term corrosion rates in dynamic seawater environments.展开更多
Horizontal axis tidal turbines have attracted more and more attentions nowadays, because of their convenience and low expense in construction and high efficiency in extracting tidal energy. The present study numerical...Horizontal axis tidal turbines have attracted more and more attentions nowadays, because of their convenience and low expense in construction and high efficiency in extracting tidal energy. The present study numerically investigates the flow motion and performance of a horizontal axis tidal turbine with a supporting vertical cylinder under steady current. In the numerical model, the continuous equation and incompressible Reynolds-averaged Navier-Stokes equations are solved, and the volume of fluid method is employed to track free surface motion. The RNG k-ε model is adopted to calculate turbulence transport while the fractional area/volume obstacle representation method is used to describe turbine characteristics and movement. The effects of installation elevation of tidal turbine and inlet velocity on the water elevation, and current velocity, rotating speed and resultant force on turbine are discussed. Based on the comparison of the numerical results, a better understanding of flow structure around horizontal axis tidal turbine and turbine performance is achieved.展开更多
基金Supported by the National Nature Science Foundation of China under Grant No.51109020 the National Key Project for Basic Research“973”（2009CB320805）
文摘Small water-plane area twin-hull（SWATH） has drawn the attention of many researchers due to its good sea-keeping ability.In this paper,MMG＇s idea of separation was used to perform SWATH movement modeling and simulation;respectively the forces and moment of SWATH were divided into bare hull,propeller,rudder at the fluid hydrodynamics,etc.Wake coefficient at the propellers which reduces thrust coefficient,and rudder mutual interference forces among the hull and propeller,for the calculation of SWATH,were all considered.The fourth-order Runge-Kutta method of integration was used by solving differential equations,in order to get SWATH＇s movement states.As an example,a turning test at full speed and full starboard rudder of ‘Seagull＇ craft is shown.The simulation results show the SWATH＇s regular pattern and trend of motion.It verifies the correctness of the mathematical model of the turning movement.The SWATH＇s mathematical model is applied to marine simulator in order to train the pilots or seamen,or safety assessment for ocean engineering project.Lastly,the full mission navigation simulating system（FMNSS） was determined to be a successful virtual reality technology application sample in the field of navigation simulation.
基金supported by the National Natural Science Foundation of China(Nos.U20A20279 and 51601137)the Hubei Province Key Laboratory of Systems Science in Metallurgical Process(No.Y202207).
文摘The effects of hydrostatic pressure, dissolved oxygen, temperature and flow velocity, and their interaction on the corrosion rates of E690 high-strength steel (HSS) in simulated marine environments were studied using response surface methodology. The results show that the flow velocity exerts the most significant influence on the corrosion rate of E690 HSS. Consequently, the corrosion behavior of E690 HSS under varying flow velocities were analyzed profoundly from initial pitting corrosion to long-term corrosion properties. The results indicate that the flow state facilitates the mass transfer and enhances the adsorption tendency of Cl− by enhancing the electrochemical activity of the steel surface. These factors accelerate the electrochemical reactions, resulting in increased pitting density, depth and the long-term corrosion rates in dynamic seawater environments.
基金funded by by the National Science Fund for Distinguished Young Scholars(Grant No.51425901)the National Natural Science Foundation of China(Grant Nos.51479053 and 51137002)+4 种基金the Natural Science Foundation of Jiangsu Province(Grant No.BK2011026)the 111 Project(Grant No.B2012032)the Specialized Research Funding for the Doctoral Program of Higher Education(Grant No.20130094110014)the Marine Renewable Energy Research Project of State Oceanic Administration(Grant No.GHME2013GC03)the Fundamental Research Funds for the Central University(Hohai University,Grant Nos.2013B31614 and 2014B04114)
文摘Horizontal axis tidal turbines have attracted more and more attentions nowadays, because of their convenience and low expense in construction and high efficiency in extracting tidal energy. The present study numerically investigates the flow motion and performance of a horizontal axis tidal turbine with a supporting vertical cylinder under steady current. In the numerical model, the continuous equation and incompressible Reynolds-averaged Navier-Stokes equations are solved, and the volume of fluid method is employed to track free surface motion. The RNG k-ε model is adopted to calculate turbulence transport while the fractional area/volume obstacle representation method is used to describe turbine characteristics and movement. The effects of installation elevation of tidal turbine and inlet velocity on the water elevation, and current velocity, rotating speed and resultant force on turbine are discussed. Based on the comparison of the numerical results, a better understanding of flow structure around horizontal axis tidal turbine and turbine performance is achieved.
