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
Traditional type pumped storage system contributes to adjust the electric power unbalance between day and night, in general. The pump-turbine unit is prepared for the power stabilization system, in this serial researc...Traditional type pumped storage system contributes to adjust the electric power unbalance between day and night, in general. The pump-turbine unit is prepared for the power stabilization system, in this serial research, to provide the constant power with good quality for the grid system, even at the suddenly fluctuating/turbulent output from renewable energies. In the unit, the angular momentum changes through the front impeller/runner must be the same as that through the rear impeller/runner, that is, the axial flow at the outlet should be the same to the axial flow at the inlet. Such flow conditions are advantageous to work at not only the pumping mode but also the turbine mode. This work discusses experimentally the performance of the unit, and verifies that this type unit is very effective to both operating modes.展开更多
Ocean energy has a potential of providing a large amount of renewable energy around the world. One of the forms of ocean energy, tidal stream power is widely recognized as the continuous, predictable and eco-friendly ...Ocean energy has a potential of providing a large amount of renewable energy around the world. One of the forms of ocean energy, tidal stream power is widely recognized as the continuous, predictable and eco-friendly ocean energy source. Unique tandem propellers that can counter-rotate have been designed to generate electric power effectively from a tidal stream. This type of power unit has several advantages compare to the conventional unit with a single propeller. At the design of the tidal stream power unit, it is important to investigate the structure of the tip vortex tubes shedding to predict the load of the propeller. In this research, we investigated the tip vortex shedding using the CFD method for the conventional single propeller and counter-rotating type tandem propellers and estimated the performance efficiency using RANS (Reynolds Averaged Navier-Stokes) model and we confirmed the limitation of RANS model on the calculation of the tip vortex stretching.展开更多
This serial research proposes the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit,to provide the constant output for the grid system,even at the suddenly fluctuating/t...This serial research proposes the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit,to provide the constant output for the grid system,even at the suddenly fluctuating/turbulent wind.In this paper,the tandem impellers of the counter-rotating type pumping unit was operated at the turbine mode,and the performances and the flow conditions were investigated numerically and experimentally.The 3-D turbulent flows in the runners were simulated at the steady state condition by using the commercial CFD code of ANSYS-CFX ver.12 with the SST turbulence model.While providing the pump unit for the turbine mode,the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclu-sively for the turbine mode.Besides,the runner/impeller of the unit works evidently so as to coincide the angularmomentum change through the front runners/impellers with that through the rear runners/impellers,namely to take the axial flow at not only the inlet but also the outlet without the guide vanes.These results show that this type of unit is effective to work at not only the pumping but also the turbine modes.展开更多
The underwater counter-rotation propeller non-cavitation noise has an obvious mod- ulation characteristic which is due to the interaction of flow and blade. A modulation mecha- nism is presented in this paper. A sound...The underwater counter-rotation propeller non-cavitation noise has an obvious mod- ulation characteristic which is due to the interaction of flow and blade. A modulation mecha- nism is presented in this paper. A sound pressure spectrum model is presented to describe its non-cavitation noise with application of generalized acoustic analogy method, the modulation mechanism is expressed with the improvement of sound pressure model. The power spectrum and modulation spectrum are presented by numerical simulation. Theoretical analysis and nu- merical simulation results are verified by the cavitation tunnel experiment. The modulation model of counter-rotation propeller is beneficial to the prediction modulation characteristics and identification of underwater high-speed vehicles.展开更多
The authors had invented the unique wind power unit composed of the large-sized front wind rotor,the small-sized rear wind rotor and the peculiar generator with the inner and the outer rotational armatures without the...The authors had invented the unique wind power unit composed of the large-sized front wind rotor,the small-sized rear wind rotor and the peculiar generator with the inner and the outer rotational armatures without the conventional stator.This unit is called "Intelligent Wind Power Unit" by the authors.The front and the rear wind rotors drive the inner and the outer armatures,respectively,while the rotational torque is counter-balanced between both armatures/wind rotors.This paper discusses experimentally the acoustic noise from the front and the rear wind rotors.The acoustic noise,in the counter-rotating operation,is induced mainly from the flow interaction between both rotors,and has the dominant power spectrum density at the frequency of the blade passing interaction.The noise is caused mainly from the turbulent fluctuation due to the flow separation on the blade,when the rear wind rotor stops or rotates in the same direction as the front wind rotor.展开更多
This serial research has proposed the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit, to provide the constant output for the grid system, even at the suddenly fluctua...This serial research has proposed the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit, to provide the constant output for the grid system, even at the suddenly fluctuating/turbulent wind circumstance. In this paper, the tandem impellers prepared for the counter-rotating type pumping unit were operated at the turbine mode, and the performances and the flow conditions were investigated numerically with accompanying the experimental results. Even though providing the pumping unit for the turbine mode, the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclusively for the turbine mode. Besides, the runners/impellers of the unit work evidently so as to coincide the angular momentum change through the front runners/impellers with that through the rear runners/impellers, namely to take the axial flow at not only the inlet but also the outlet, without the guide vanes. From these results, it can be concluded that this type unit is effective to work at not only the pumping but also the turbine modes.展开更多
It is difficult for renewable energy resources to provide constant power with excellent quality for the grid system. This serial research proposes a power stabilization system with a pumped storage to guarantee power ...It is difficult for renewable energy resources to provide constant power with excellent quality for the grid system. This serial research proposes a power stabilization system with a pumped storage to guarantee power quality and capacity, while the outputs from the energy resources are at unstable and/or fluctuating conditions. The power stabilization system with a counter-rotating type pump-turbine unit was prepared and operated at the pumping and the turbine modes. The unit composed of the tandem impellers/runners connected to the inner and the outer armatures of the unique motor/generator. The experiments have verified that this type pump-turbine unit is reasonably effective to stabilize momentarily/instantaneously the fluctuating power from the renewable energy resources.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
Line-Spectrum noise of counter-rotation propellers has constructed the main part of the radiated noise of high speed vehicles in water. The line-spectrum noise of the counter-rotation propellers is due to the interact...Line-Spectrum noise of counter-rotation propellers has constructed the main part of the radiated noise of high speed vehicles in water. The line-spectrum noise of the counter-rotation propellers is due to the interaction between fore or aft propeller and wake of the vehicle,and the interaction between fore and aft propeller. Based on a combination of the lifting surface theory and acoustic method, the prediction of line-spectrum noise is presented in this paper.Theoretical calculation method, characteristics and numerical prediction of the line-spectrum noise are detailed too. The effect of different wake and different distance between fore and aft propeller on the propeller noise is also studied by numerical method. The agreement of predicted results compared with existing experimental data is quite satisfactory.展开更多
The authors have invented the unique ocean wave power station,which is composed of the floating type platform with a pair of the floats lining up at the interval of one wave pitch and the counter-rotating type wave po...The authors have invented the unique ocean wave power station,which is composed of the floating type platform with a pair of the floats lining up at the interval of one wave pitch and the counter-rotating type wave power unit,its runners are submerged in the seawater at the middle position of the platform.Such profiles make the flow velocity at the runner is twice faster than that of the traditional fixed/caisson type OWC,on the ideal flow conditions.Besides,the runners counter-rotate the inner and the outer armatures of the peculiar generator,respectively,and the relative rotational speed is also twice faster than the speed of the single runner/armature.Such characteristics make the runner diameter large,namely the output higher,as requested,because the torque of the power unit never act on the floating type platform.At the preliminary reseach,this paper verifies to get the power using a Wells type single runner installed in the model station.The runner takes the output which is affected by the oscillating amplitude of the platform,the rotational speed and the inertia force of the runner,etc.展开更多
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Traditional type pumped storage system contributes to adjust the electric power unbalance between day and night, in general. The pump-turbine unit is prepared for the power stabilization system, in this serial research, to provide the constant power with good quality for the grid system, even at the suddenly fluctuating/turbulent output from renewable energies. In the unit, the angular momentum changes through the front impeller/runner must be the same as that through the rear impeller/runner, that is, the axial flow at the outlet should be the same to the axial flow at the inlet. Such flow conditions are advantageous to work at not only the pumping mode but also the turbine mode. This work discusses experimentally the performance of the unit, and verifies that this type unit is very effective to both operating modes.
文摘Ocean energy has a potential of providing a large amount of renewable energy around the world. One of the forms of ocean energy, tidal stream power is widely recognized as the continuous, predictable and eco-friendly ocean energy source. Unique tandem propellers that can counter-rotate have been designed to generate electric power effectively from a tidal stream. This type of power unit has several advantages compare to the conventional unit with a single propeller. At the design of the tidal stream power unit, it is important to investigate the structure of the tip vortex tubes shedding to predict the load of the propeller. In this research, we investigated the tip vortex shedding using the CFD method for the conventional single propeller and counter-rotating type tandem propellers and estimated the performance efficiency using RANS (Reynolds Averaged Navier-Stokes) model and we confirmed the limitation of RANS model on the calculation of the tip vortex stretching.
基金co-sponsored by Japan Society for the Promotion of Science KAKENHI23860035
文摘This serial research proposes the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit,to provide the constant output for the grid system,even at the suddenly fluctuating/turbulent wind.In this paper,the tandem impellers of the counter-rotating type pumping unit was operated at the turbine mode,and the performances and the flow conditions were investigated numerically and experimentally.The 3-D turbulent flows in the runners were simulated at the steady state condition by using the commercial CFD code of ANSYS-CFX ver.12 with the SST turbulence model.While providing the pump unit for the turbine mode,the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclu-sively for the turbine mode.Besides,the runner/impeller of the unit works evidently so as to coincide the angularmomentum change through the front runners/impellers with that through the rear runners/impellers,namely to take the axial flow at not only the inlet but also the outlet without the guide vanes.These results show that this type of unit is effective to work at not only the pumping but also the turbine modes.
基金supported by the National Natural Science Foundation of China(11704345)the Key Laboratory of Science and Technology for National Defence Foundation(9140C290304140C29133)
文摘The underwater counter-rotation propeller non-cavitation noise has an obvious mod- ulation characteristic which is due to the interaction of flow and blade. A modulation mecha- nism is presented in this paper. A sound pressure spectrum model is presented to describe its non-cavitation noise with application of generalized acoustic analogy method, the modulation mechanism is expressed with the improvement of sound pressure model. The power spectrum and modulation spectrum are presented by numerical simulation. Theoretical analysis and nu- merical simulation results are verified by the cavitation tunnel experiment. The modulation model of counter-rotation propeller is beneficial to the prediction modulation characteristics and identification of underwater high-speed vehicles.
基金co-sponsored by Research Project 2007 "Grand-in-aid for Scientific Research (c) (2) in Japan" and Research project:Grant-in-aid for JSPS fellow
文摘The authors had invented the unique wind power unit composed of the large-sized front wind rotor,the small-sized rear wind rotor and the peculiar generator with the inner and the outer rotational armatures without the conventional stator.This unit is called "Intelligent Wind Power Unit" by the authors.The front and the rear wind rotors drive the inner and the outer armatures,respectively,while the rotational torque is counter-balanced between both armatures/wind rotors.This paper discusses experimentally the acoustic noise from the front and the rear wind rotors.The acoustic noise,in the counter-rotating operation,is induced mainly from the flow interaction between both rotors,and has the dominant power spectrum density at the frequency of the blade passing interaction.The noise is caused mainly from the turbulent fluctuation due to the flow separation on the blade,when the rear wind rotor stops or rotates in the same direction as the front wind rotor.
文摘This serial research has proposed the hybrid power system combined the wind power unit with the counter-rotating type pump-turbine unit, to provide the constant output for the grid system, even at the suddenly fluctuating/turbulent wind circumstance. In this paper, the tandem impellers prepared for the counter-rotating type pumping unit were operated at the turbine mode, and the performances and the flow conditions were investigated numerically with accompanying the experimental results. Even though providing the pumping unit for the turbine mode, the maximum hydraulic efficiency is close to one of the counter-rotating type hydroelectric unit designed exclusively for the turbine mode. Besides, the runners/impellers of the unit work evidently so as to coincide the angular momentum change through the front runners/impellers with that through the rear runners/impellers, namely to take the axial flow at not only the inlet but also the outlet, without the guide vanes. From these results, it can be concluded that this type unit is effective to work at not only the pumping but also the turbine modes.
文摘It is difficult for renewable energy resources to provide constant power with excellent quality for the grid system. This serial research proposes a power stabilization system with a pumped storage to guarantee power quality and capacity, while the outputs from the energy resources are at unstable and/or fluctuating conditions. The power stabilization system with a counter-rotating type pump-turbine unit was prepared and operated at the pumping and the turbine modes. The unit composed of the tandem impellers/runners connected to the inner and the outer armatures of the unique motor/generator. The experiments have verified that this type pump-turbine unit is reasonably effective to stabilize momentarily/instantaneously the fluctuating power from the renewable energy resources.
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Line-Spectrum noise of counter-rotation propellers has constructed the main part of the radiated noise of high speed vehicles in water. The line-spectrum noise of the counter-rotation propellers is due to the interaction between fore or aft propeller and wake of the vehicle,and the interaction between fore and aft propeller. Based on a combination of the lifting surface theory and acoustic method, the prediction of line-spectrum noise is presented in this paper.Theoretical calculation method, characteristics and numerical prediction of the line-spectrum noise are detailed too. The effect of different wake and different distance between fore and aft propeller on the propeller noise is also studied by numerical method. The agreement of predicted results compared with existing experimental data is quite satisfactory.
文摘The authors have invented the unique ocean wave power station,which is composed of the floating type platform with a pair of the floats lining up at the interval of one wave pitch and the counter-rotating type wave power unit,its runners are submerged in the seawater at the middle position of the platform.Such profiles make the flow velocity at the runner is twice faster than that of the traditional fixed/caisson type OWC,on the ideal flow conditions.Besides,the runners counter-rotate the inner and the outer armatures of the peculiar generator,respectively,and the relative rotational speed is also twice faster than the speed of the single runner/armature.Such characteristics make the runner diameter large,namely the output higher,as requested,because the torque of the power unit never act on the floating type platform.At the preliminary reseach,this paper verifies to get the power using a Wells type single runner installed in the model station.The runner takes the output which is affected by the oscillating amplitude of the platform,the rotational speed and the inertia force of the runner,etc.
文摘为了研究对转桨和单桨的目标特性差异,在大型空泡水筒中针对单桨和对转桨的非空泡和空泡工况进行了噪声测量试验,采集了单桨和对转桨在空化条件和非空化条件下的噪声信号。首先针对空泡水筒自身特性进行了分析研究,发现空泡水筒在1.8 kHz和3.8 kHz附近易产生混响干扰。其次,借助数字信号处理技术对测量的声信号进行谱分析,对比研究了单桨和对转桨在空化条件和非空化条件下噪声信号在频域上的差异和规律,并采用频闪仪和高速摄像机对桨叶空泡进行了观察。试验表明,在非空化条件下,相同工况时对转桨噪声级比单桨高6 d B以上,对转桨倍频程衰减值要小于单桨,对转桨和单桨的三分之一倍频程谱在1.8 kHz和3.8 kHz附近会出现峰值,单桨8 kHz附近峰值是由唱音引起;在空化条件下,相同工况时对转桨和单桨三分之一倍频程谱变化趋势基本一致,对转桨噪声级比单桨高3~20 d B。在空化和非空化条件下,对转桨的调制谱特征比单桨复杂,对转桨的调制频段要远大于单桨,对转桨前后桨一阶叶频组合的调制作用最强,而单桨一阶叶频调制作用最强。
