In this paper,the coupled sloshing and motion characteristics of a cylindrical floating production storage offloading(CFPSO)are numerically investigated by means of computational fluid dynamics(CFD)tool.The simulation...In this paper,the coupled sloshing and motion characteristics of a cylindrical floating production storage offloading(CFPSO)are numerically investigated by means of computational fluid dynamics(CFD)tool.The simulations are performed using an in-house CFD solver naoe-FOAM-SJTU which is developed based on OpenFOAM.The active wave generating-absorbing boundary condition(GABC)is utilized for wave generation and absorption.The stabilized k-omega SST turbulence model are used to avoid excessive eddy viscosity near the free surface.CFPSO with and without partially filled liquid tanks in regular waves with different wave periods are simulated and vertical planar motions such as surge,heave and pitch response amplitude operators(RAOs)are compared.Forces due to liquid sloshing and wave loads are extracted and analyzed.The free surface motions inside liquid tanks in one wave period presented to explain the motion characteristics.展开更多
Numerical simulations of longitudinal wave propagation in a rock bar with microcracks are conducted by using the numerical manifold method which has great advantages in the simulation of discontinuities.Firstly,valida...Numerical simulations of longitudinal wave propagation in a rock bar with microcracks are conducted by using the numerical manifold method which has great advantages in the simulation of discontinuities.Firstly,validation of the numerical manifold method is carried out by simulations of a longitudinal stress wave propagating through intact and cracked rock bars.The behavior of the stress wave traveling in a one-dimensional rock bar with randomly distributed microcracks is subsequently studied.It is revealed that the highly defected rock bar has significant viscoelasticity to the stress wave propagation.Wave attenuation as well as time delay is affected by the length,quantity,specific stiffness of the distributed microcracks as well as the incident stress wave frequency.The storage and loss moduli of the defected rock are also affected by the microcrack properties;however,they are independent of incident stress wave frequency.展开更多
Wave energy is an important renewable energy source. Previous studies of wave energy conversion(WEC) have focused on the maximum power take-off(PTO) techniques of a single machine. However, there is a lack of research...Wave energy is an important renewable energy source. Previous studies of wave energy conversion(WEC) have focused on the maximum power take-off(PTO) techniques of a single machine. However, there is a lack of research on the energy and power quality of wave farm systems. Owing to the pulsating nature of ocean waves and popular PTO devices, the generated electrical power suffers from severe fluctuations. Existing solutions require extra energy storage and overrated power converters for wave power integration. In this study, we developed a master-slave wave farm system with rotor inertia energy storage; this system delivers self-smoothed power output to the grid and reduces the number of converters. Two control methods based on the moving average filter(MAF) and energy filter(EF) are proposed to smooth the output power of wave farms. RTDS simulations show that the proposed systems and control methods facilitate simple and smooth grid integration of wave energy.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2022YFC2806705)the National Natural Science Foundation of China(Grant No.52131102).
文摘In this paper,the coupled sloshing and motion characteristics of a cylindrical floating production storage offloading(CFPSO)are numerically investigated by means of computational fluid dynamics(CFD)tool.The simulations are performed using an in-house CFD solver naoe-FOAM-SJTU which is developed based on OpenFOAM.The active wave generating-absorbing boundary condition(GABC)is utilized for wave generation and absorption.The stabilized k-omega SST turbulence model are used to avoid excessive eddy viscosity near the free surface.CFPSO with and without partially filled liquid tanks in regular waves with different wave periods are simulated and vertical planar motions such as surge,heave and pitch response amplitude operators(RAOs)are compared.Forces due to liquid sloshing and wave loads are extracted and analyzed.The free surface motions inside liquid tanks in one wave period presented to explain the motion characteristics.
文摘Numerical simulations of longitudinal wave propagation in a rock bar with microcracks are conducted by using the numerical manifold method which has great advantages in the simulation of discontinuities.Firstly,validation of the numerical manifold method is carried out by simulations of a longitudinal stress wave propagating through intact and cracked rock bars.The behavior of the stress wave traveling in a one-dimensional rock bar with randomly distributed microcracks is subsequently studied.It is revealed that the highly defected rock bar has significant viscoelasticity to the stress wave propagation.Wave attenuation as well as time delay is affected by the length,quantity,specific stiffness of the distributed microcracks as well as the incident stress wave frequency.The storage and loss moduli of the defected rock are also affected by the microcrack properties;however,they are independent of incident stress wave frequency.
基金supported by EPSRC under Grant EP/ L017725/1 and Grant EP/N032888/1
文摘Wave energy is an important renewable energy source. Previous studies of wave energy conversion(WEC) have focused on the maximum power take-off(PTO) techniques of a single machine. However, there is a lack of research on the energy and power quality of wave farm systems. Owing to the pulsating nature of ocean waves and popular PTO devices, the generated electrical power suffers from severe fluctuations. Existing solutions require extra energy storage and overrated power converters for wave power integration. In this study, we developed a master-slave wave farm system with rotor inertia energy storage; this system delivers self-smoothed power output to the grid and reduces the number of converters. Two control methods based on the moving average filter(MAF) and energy filter(EF) are proposed to smooth the output power of wave farms. RTDS simulations show that the proposed systems and control methods facilitate simple and smooth grid integration of wave energy.
