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1.
Experimental Investigation on the Hydrodynamic Performance of A Wave Energy Converter 总被引：1，自引：0，他引：1
Wave energy is an important type of marine renewable energy. A wave energy converter (WEC) moored with two floating bodies was developed in the present study. To analyze the dynamic performance of the WEC, an experimental device was designed and tested in a tank. The experiment focused on the factors which impact the motion and energy conversion performance of the WEC. Dynamic performance was evaluated by the relative displacements and velocities of the oscillator and carrier which served as the floating bodies of WEC. Four factors were tested, i.e. wave height, wave period, power take-off (PTO) damping, and mass ratio (RM) of the oscillator and carrier. Experimental results show that these factors greatly affect the energy conversion performance, especially when the wave period matches RM and PTO damping. According to the results, we conclude that: (a) the maximization of the relative displacements and velocities leads to the maximization of the energy conversion efficiency; (b) the larger the wave height, the higher the energy conversion efficiency will be; (c) the relationships of energy conversion efficiency with wave period, PTO damping, and RM are nonlinear, but the maximum efficiency is obtained when these three factors are optimally matched. Experimental results demonstrated that the energy conversion efficiency reached the peak at 28.62% when the wave height was 120 mm, wave period was 1.0 s, RM was 0.21, and the PTO damping was corresponding to the resistance of 100 Ω. 相似文献
2.
In coastal sea areas with the bimodal Ochi-Hubble wave spectrum, such as parts of the China Sea and Indian Ocean,wave energy is the superposition of wind wave and swell. Traditional heaving buoy wave energy converters developed with narrowband wave spectrums suffer from big energy loss in these areas, leading to lower power absorption efficiency and higher generating costs. In contrast, multi-freedom buoy has different resonant frequencies and maximal power capture wave frequencies in different ... 相似文献
3.
Investigation on the Oscillating Buoy Wave Power Device 总被引：4，自引：0，他引：4
An oscillating buoy wave power device (OD) is a device extracting wave power by an oscillating buoy. Being excited by waves, the buoy heaves up and down to convert wave energy into electricity by means of a mechanical or hydraulic device. Compared with an Oscillating Water Column (OWC) wave power device, the OD has the same capture vvidth ratio as the OWC does, but much higher secondary conversion efficiency. Moreover, the chamber of the OWC, which is the most expensive and difficult part to be built, is not necessary for the OD, so it is easier to construct an OD. In this paper, a nu-merical calculation is conducted for an optimal design of the OD firstly, then a model of the device is built and, a model test is carried out in a wave tank. The results show that the total efficiency of the OD is much higher than that of the OWC and that the OD is a promising wave power device. 相似文献
4.
In the water jet propulsion system with a positive displacement （PD） pump, the nozzle, which converts pressure energy into kinetic energy, is one of the key parts exerting great influence on the reactive thrust and the efficiency of the system due to its high working pressure and easily occurring cavitation characteristics. Based on the previous studies of the energy loss and the pressure distribution of different nozzles, a model of water jet reactive thrust, which fully takes the energy loss and the nozzle parameters into consideration, is developed to optimize the nozzle design. Experiments and simulations are carried out to investigate the reactive thrust and the conversion efficiency of cylindrical nozzles, conical nozzles and optimized nozzles. The results show that the optimized nozzles have the largest reactive thrust and the highest energy conversion efficiency under the same inlet conditions. The related methods and conclusions are extended to the study of other applications of the water jet, such as water jet cutting, water mist fire suppression, water injection molding. 相似文献
5.
Power Maximization of A Point Absorber Wave Energy Converter Using Improved Model Predictive Control 总被引：1，自引：0，他引：1
This paper considers controlling and maximizing the absorbed power of wave energy converters for irregular waves. With respect to physical constraints of the system, a model predictive control is applied. Irregular waves’ behavior is predicted by Kalman filter method. Owing to the great influence of controller parameters on the absorbed power, these parameters are optimized by imperialist competitive algorithm. The results illustrate the method’s efficiency in maximizing the extracted power in the presence of unknown excitation force which should be predicted by Kalman filter. 相似文献
6.
7.
A wave power device includes an energy harvesting system and a power take-off system. The power take-off system of a floating wave energy device is the key that converts wave energy into other forms. A set of hydraulic power take-off system, which suits for the floating wave energy devices, includes hydraulic system and power generation system. The hydraulic control system uses a special“self-hydraulic control system”to control hydraulic system to release or save energy under the maximum and the minimum pressures. The maximum pressure is enhanced to 23 MPa, the minimum to 9 MPa. Quite a few experiments show that the recent hydraulic system is evidently improved in efficiency and reliability than our previous one, that is expected to be great significant in the research and development of our prototype about wave energy conversion. 相似文献
8.
《中国海洋工程》1990,(4)
This paper deals with the nonlinear effect of the drift motion of multi-chain mooring buoys. The buoy's motion in time domain is determined for the case that the wave and mooring force are nonlinear. The Kotorayama's method of hydrodynamic effect in a single mooring chain is expanded to multi-mooring chains. The time history of drift motion of the mooring buoy in regular waves and wave groups is calculated. The relation between the drift motion and the wave height or difference frequency is discussed. It can be shown that the effect of the hydrodynamic force acting on the mooring chain has remarkable influence on the total drift motion of the mooring buoy. In a wave group, its amplitude is mainly controled by the wave height and has little relation with difference frequency. 相似文献
9.
Down-scaled regional ocean modeling system (ROMS) for high-resolution coastal hydrodynamics in Korea 总被引：1，自引：0，他引：1
A down-scaled operational oceanographic system is developed for the coastal waters of Korea using a regional ocean modeling system(ROMS).The operational oceanographic modeling system consists of atmospheric and hydrodynamic models.The hydrodynamic model,ROMS,is coupled with wave,sediment transport,and water quality modules.The system forecasts the predicted results twice a day on a 72 h basis,including sea surface elevation,currents,temperature,salinity,storm surge height,and wave information for the coastal waters of Korea.The predicted results are exported to the web-GIS-based coastal information system for real-time dissemination to the public and validation with real-time monitoring data using visualization technologies.The ROMS is two-way coupled with a simulating waves nearshore model,SWAN,for the hydrodynamics and waves,nested with the meteorological model,WRF,for the atmospheric surface forcing,and externally nested with the eutrophication model,CE-QUAL-ICM,for the water quality.The operational model,ROMS,was calibrated with the tidal surface observed with a tide-gage and verified with current data observed by bottom-mounted ADCP or AWAC near the coastal waters of Korea.To validate the predicted results,we used real-time monitoring data derived from remote buoy system,HF-radar,and geostationary ocean color imager(GOCI).This down-scaled operational coastal forecasting system will be used as a part of the Korea operational oceanographic system(KOOS) with other operational oceanographic systems. 相似文献
10.
Although Morison equation is often applied for simulating hydrodynamic force of marine structure, it may give poor results when non-linear behavior is severe or random wave is encountered. This leads to some modifications of Morison equation or other methods for predicting hydrodynamic force. One of them is the system identification technique. In this paper, NARMAX model theory is firstly used to identify the hydrodynamic system of heave damping plates, which are commonly installed on spar platform. Both linear and non-linear models are obtained. The comparisons between the predieted results and measured data indicate that NARMAX model can predict hydrodynamic force of a heave damping plate very well. The measured data for identification originate from forced oscillation tests, which are random records with given spectrum. The forced oscillation forms in experiment also contain simple harmonic, multi-frequency ones. 相似文献
11.
Dynamic analysis of wave energy converter by incorporating the effect of hydraulic transmission lines 总被引：1，自引：0，他引：1
A heaving-buoy wave energy converter equipped with hydraulic power take-off is studied in this paper. This wave energy converter system is divided into five subsystems: a heaving buoy, hydraulic pump, pipelines, non-return check valves and a hydraulic motor combined with an electric generator. A dynamic model was developed by considering the interactions between the subsystems in a state space form. The transient pressures caused by starting/stopping the buoy or closing/opening the check valves were predicted numerically using the established model. The simulation results show that transmission line dynamics play a dominant role in the studied wave energy converter system. The length of the pipeline will not only affect the amplitude of the transient pressures but also affect the converted power. The variation of the time-averaged converted electric power with the pipeline length is estimated using the simulation method for the buoy exposed to one irregular sea state. Finally, it is suggested how reduced power efficiency due to the pipelines may be ameliorated. 相似文献
12.
Ocean wave energy is an emerging kind of renewable energy, and several energy conversion methods are available today. One solution is to connect a buoy to a linear generator. Such units are quite small (10–100 kW), and farm solutions are suggested to increase power production. This paper shows the results from small farm simulations where the translator motion is varied for the generators in the farm.Simulations with five and 10 units show that power fluctuations decrease with an increasing number of generators. 相似文献
13.
为了提高中心管振荡水柱波浪能利用技术能量转换效率,基于新的认识和目前常用的2.4米导航灯标,对中心管尾部设计了三种模型并在造波水槽中进行能量转换性能试验。试验结果表明:直管型中心管俘获宽度比最高达到了70.25%,但通频带宽度窄;加长喇叭口型中心管略好于喇叭口型中心管;在喷咀比为0.02条件下,加长喇叭口型中心管浮体有较高双峰俘获宽度比,波峰为40.0%,波谷为31.6%,通频带宽,为随机波下高效转换创造了条件。最高俘获宽度比和双峰通频带特性实验数据结果都优于历史文献值。根据试验数据对一些适合小型海洋仪器供电的样机进行了设计,设计的样机具有较高的性价比。 相似文献
14.
This paper investigates latching type control on a floating wave energy converter in deep water. An on-board, actively controlled motion-compensated platform is used as a reference (‘active reference’) for power absorption and latching. A variational formulation is used to evaluate an optimal control sequence in the time domain. Time domain simulation results are presented for a heaving buoy in small-amplitude waves. Results are compared with an equivalent system where latching and power absorption are from a sea-bottom-fixed reference. 相似文献
15.
针对阵列式振荡浮子波浪能转换设备,提出一种在实验室进行测试研究的实验装置。该实验装置由一组阵列柱形水槽组成,水槽液面在水动力系统的驱动下,按照计算机设定的函数做升降运动;对该装置模型——柱形阵列水槽的假设,依据波浪理论进行了论证;对装置的工作原理、结构设计、技术参数、控制电路和操作运行等做了较详细的说明;对实验装置实际运行和测试情况做了介绍。结果表明:该实验装置设计合理可行,模拟波浪高度,远高于现有的造波水池,构成了一种专用的模拟造波装置;该装置为不同形式振荡浮子式波浪能转换设备的研制提供了一种多功能、大振幅、高效灵活的实验平台。 相似文献
16.
Point absorber wave energy device with multiple degrees of freedom (DOF) is assumed to have a better absorption ability of mechanical energy from ocean waves. In this paper, a coaxial symmetric articulated point absorber wave energy converter with two degrees of freedom is presented. The mechanical equations of the oscillation buoy with power take-off mechanism (PTO) in regular waves are established. The three-dimensional numerical wave tank is built in consideration of the buoy motion based upon the CFD method. The appropriate simulation elements are selected for the buoy and wave parameters. The feasibility of the CFD method is verified through the contrast between the numerical simulation results of typical wave conditions and test results. In such case, the buoy with single DOF of heave, pitch and their coupling motion considering free (no PTO damping) and damped oscillations in regular waves are simulated by using the verified CFD method respectively. The hydrodynamic and wave energy conversion characteristics with typical wave conditions are analyzed. The numerical results show that the heave and pitch can affect each other in the buoy coupling motion, hydrodynamic loads, wave energy absorption and flow field. The total capture width ratio with two coupled DOF motion is higher than that with a single DOF motion. The wave energy conversion of a certain DOF motion may be higher than that of the single certain DOF motion even though the wave is at the resonance period. When the wave periods are high enough, the interaction between the coupled DOF motions can be neglected. 相似文献
17.
针对我国波浪发电的发展现状,介绍了“海蛇”波浪发电装置的发电原理,并应用OrcaFlex 软件建立了装置的水动力数值模型,研究了“海蛇”装置浮筒的水动力特性.根据“海蛇”装置的结构特点,通过对活塞运动的时程曲线进行傅里叶变换,给出此装置一级转化总势能计算的简易方法.另外,通过改变浮筒的直径和长度,以装置的效率/体积比作为衡量系统经济性的指标,研究浮筒几何参数对装置一级能量转化效率的影响.结果表明,装置一级能量转化效率随浮筒长度和直径增加而变大,进一步分析表明,适当增加浮筒长度比增大直径更具经济效益.装置的效率/体积比随着浮筒直径增加存在先增加后减少的拐点,这可以为“海蛇”的初始设计提供一定的理论依据. 相似文献
18.
Michael E. McCormick 《Ocean Engineering》1976,3(3):133-144
The analysis of a pneumatic-type wave-energy conversion buoy is developed assuming independence of the buoy heaving motion and the motion of the water column within the center pipe. Results of the analysis are then compared with experimental data in a study of the relative air velocity within the turbine passage. The results compare very well. The effect of the variation of the center pipe length is found to be significant for periods about the surge chamber resonance but is negligible in the neighborhood of the heaving resonance period. Further, the theory is applied to a prototype buoy study of the U.S. Coast Guard, and a dimensionless design curve is developed from the results of the prototype analysis. 相似文献
19.
该研究提出了一种新型磁力双稳态机构,主要由一对同向充磁的负刚度磁环,附加一对异向充磁的正刚度磁环组成,可通过调整磁环参数有效改变双稳态装置的势垒高度,从而克服传统型双稳态装置在小幅波浪激励下转换效率低的难题。基于Cummins方程建立了系统的时域非线性动力学模型,其中采用状态空间模型替代了辐射力的卷积积分项用于加快计算速度。采用四阶龙格库塔方法求解动力学方程,获得系统响应解。采用Jonswap波浪谱,研究了不规则波激励下波浪能转换装置的转换效率随双稳态结构参数以及波浪激励参数的变化规律。结果表明,新型磁力双稳态机构在合适参数下可以达到降低势垒高度和拓宽平衡点间距的效果,从而显著提高波能捕获效率,拓宽波能捕获频带,尤其是大幅提高了系统在小波高激励下的捕获宽度。 相似文献