This paper presents the heave responses and the moonpool water motions of a truss Spar platform with semi-closed moonpool in random waves. A 2-DOF（degree of freedom） coupling dynamical equations of the platform heav...This paper presents the heave responses and the moonpool water motions of a truss Spar platform with semi-closed moonpool in random waves. A 2-DOF（degree of freedom） coupling dynamical equations of the platform heave and vertical motions of the moonpool water are derived. The linear wave theory is used to simulate the random waves. The response statistical values and the power spectrums are calculated to analyze the mutual influences between the platform heave and the moonpool water motions for different opening ratios of the moonpool. The effect of coupling parameters on the platform heave and the moonpool water motions are analyzed. The results show that motions of the moonpool water significantly affected the platform heave when the characteristic wave period is far away from the natural period of the platform heave, and different moonpool opening ratios lead to different heave amplitudes of the platform. In the actual design, an optimized moonpool opening ratio can be designed to reduce heave motions of the platform.展开更多
This serial research develops the unique ocean wave power station, which is composed of the floating type platform with a pair of the floats arranged at the interval of one wavelength and the counter-rotating type wav...This serial research develops the unique ocean wave power station, which is composed of the floating type platform with a pair of the floats arranged at the interval of one wavelength and the counter-rotating type wave power unit whose runners are submerged in the seawater at the middle position of the platform. Such profiles make the flow velocity through the runners two times faster than that of the traditional fixed/caisson type OWC （oscillating water column）, that is, the runners may be able to get the dynamical energy eight times on the ideal. Besides, the runners counter-drive the inner and the outer armatures of the peculiar generator, respectively, and then the relative rotational speed is two times as fast as the speed of the single runner/armature. Such characteristics make the runner diameter large, namely the output higher, as you request, because the rotational moment of the power unit hardly act on the floating type platform. This paper, as the first step, discusses the platform behaviors at the normally oscillating wave. The platform behavior is affected by not only the length and the amplitude of the wave but also the relation between the weight of the platform and the buoyancy force of the floats.展开更多
The authors have proposed the unique ocean wave power station, which is composed of the floating type platform with a pair of floats lining up at the interval of one wave pitch and the power unit where the runners are...The authors have proposed the unique ocean wave power station, which is composed of the floating type platform with a pair of floats lining up at the interval of one wave pitch and the power unit where the runners are submerged at the middle of the platform. Such a profile can make the flow velocity at the runner twice faster than that of OWC （oscillating water column） type constructed adjacent to the seashore. The behavior of the platform in the wave has been reported, and this paper continuously investigates the effects of the runner casing on the runner work and the platform behavior. Besides, the flows around the Wells type, not only single runner but also tandem runners are investigated numerically. It was confirmed that the runner work attenuates the platform amplitude and the runner casing contributes to increase the output. The flow simulation suggests that the tandem runners may be appropriate for the floating type ocean wave power station to get enough output.展开更多
This paper proposes a new concept of an actively-controlled wave energy converter for suppressing the pitch and roll motions of floating offshore wind turbines.The wave energy converter consists of several floating bo...This paper proposes a new concept of an actively-controlled wave energy converter for suppressing the pitch and roll motions of floating offshore wind turbines.The wave energy converter consists of several floating bodies that receive the wave energy,actuators that convert the wave energy into electrical energy and generate the mechanical forces,and rigid bars that connect the floating bodies and the wind turbine platform and deliver the actuator forces to the platform.The rotational torques that are required to minimize the platform pitch and roll motions are determined using a linear quadratic regulator.The torques determined in this manner are realized through the actuator forces that maximize the wave power capture as well.The performance of the proposed wave energy converter in simultaneously suppressing the platform pitch and roll motions and extracting the wave energy is validated through simulations.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant No.51179125)the Innovation Foundation of Tianjin University(Grant No.1301)
文摘This paper presents the heave responses and the moonpool water motions of a truss Spar platform with semi-closed moonpool in random waves. A 2-DOF（degree of freedom） coupling dynamical equations of the platform heave and vertical motions of the moonpool water are derived. The linear wave theory is used to simulate the random waves. The response statistical values and the power spectrums are calculated to analyze the mutual influences between the platform heave and the moonpool water motions for different opening ratios of the moonpool. The effect of coupling parameters on the platform heave and the moonpool water motions are analyzed. The results show that motions of the moonpool water significantly affected the platform heave when the characteristic wave period is far away from the natural period of the platform heave, and different moonpool opening ratios lead to different heave amplitudes of the platform. In the actual design, an optimized moonpool opening ratio can be designed to reduce heave motions of the platform.
文摘This serial research develops the unique ocean wave power station, which is composed of the floating type platform with a pair of the floats arranged at the interval of one wavelength and the counter-rotating type wave power unit whose runners are submerged in the seawater at the middle position of the platform. Such profiles make the flow velocity through the runners two times faster than that of the traditional fixed/caisson type OWC （oscillating water column）, that is, the runners may be able to get the dynamical energy eight times on the ideal. Besides, the runners counter-drive the inner and the outer armatures of the peculiar generator, respectively, and then the relative rotational speed is two times as fast as the speed of the single runner/armature. Such characteristics make the runner diameter large, namely the output higher, as you request, because the rotational moment of the power unit hardly act on the floating type platform. This paper, as the first step, discusses the platform behaviors at the normally oscillating wave. The platform behavior is affected by not only the length and the amplitude of the wave but also the relation between the weight of the platform and the buoyancy force of the floats.
文摘The authors have proposed the unique ocean wave power station, which is composed of the floating type platform with a pair of floats lining up at the interval of one wave pitch and the power unit where the runners are submerged at the middle of the platform. Such a profile can make the flow velocity at the runner twice faster than that of OWC （oscillating water column） type constructed adjacent to the seashore. The behavior of the platform in the wave has been reported, and this paper continuously investigates the effects of the runner casing on the runner work and the platform behavior. Besides, the flows around the Wells type, not only single runner but also tandem runners are investigated numerically. It was confirmed that the runner work attenuates the platform amplitude and the runner casing contributes to increase the output. The flow simulation suggests that the tandem runners may be appropriate for the floating type ocean wave power station to get enough output.
文摘This paper proposes a new concept of an actively-controlled wave energy converter for suppressing the pitch and roll motions of floating offshore wind turbines.The wave energy converter consists of several floating bodies that receive the wave energy,actuators that convert the wave energy into electrical energy and generate the mechanical forces,and rigid bars that connect the floating bodies and the wind turbine platform and deliver the actuator forces to the platform.The rotational torques that are required to minimize the platform pitch and roll motions are determined using a linear quadratic regulator.The torques determined in this manner are realized through the actuator forces that maximize the wave power capture as well.The performance of the proposed wave energy converter in simultaneously suppressing the platform pitch and roll motions and extracting the wave energy is validated through simulations.
