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1.
Experimentally validated numerical method for the hydrodynamic design of horizontal axis tidal turbines 总被引：1，自引：0，他引：1
W.M.J. Batten A.S. Bahaj A.F. Molland J.R. Chaplin Sustainable Energy Research Group 《Ocean Engineering》2007,34(7):1013-1020
Although a lot can be learnt from technology transfer from wind turbines and ship propellers, there have been a few experiments investigating marine current turbines. As a result, a study has been carried out on the power, thrust and cavitation characteristics of 1/20th scale model of a possible 16 m diameter horizontal axis tidal turbine. Cavitation tunnel experiments for different blade pitch settings have been compared with simulations based on a developed blade element-momentum theory. This theory has been shown to provide a satisfactory representation of the experimental turbine performance characteristics. As an example application, the developed theory has been used to design possible horizontal axis tidal turbines for the tidal flows around Portland Bill. The results show that there is a clear balance between design loads and optimisation of energy yields. 相似文献
2.
在开放海域运行的潮流能水轮机需要应对复杂多变的海洋环境,要有较好的刚度、强度和抗疲劳性能。这对水轮机结构,尤其是为其运行提供动力的叶片结构的设计提出了较高要求。文中建立了垂直轴潮流能水轮机叶片及流场的三维数值计算模型,基于ANSYS商业软件提供的CFX与瞬时结构模块的双向流固耦合分析功能,分析了叶片在不同流速下的流体力学性能,分析了流场的三维效应及其引起叶片升力损失的原因,研究了其结构的刚度和强度特性。还对比分析了使用铝合金和钢材作为水轮机叶片材料的优劣。 相似文献
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Tidal current energy is prominent and renewable. Great progress has been made in the exploitation technology of tidal current energy all over the world in recent years, and the large scale device has become the trend of tidal current turbine (TCT) for its economies. Instead of the similarity to the wind turbine, the tidal turbine has the characteristics of high hydrodynamic efficiency, big thrust, reliable sealing system, tight power transmission structure, etc. In this paper, a 1/5th scale horizontal axis tidal current turbine has been designed, manufactured and tested before the full scale device design. Firstly, the three-blade horizontal axis rotor was designed based on traditional blade element momentum theory and its hydrodynamic performance was predicted in numerical model. Then the power train system and stand-alone electrical control unit of tidal current turbine, whose performances were accessed through the bench test carried out in workshop, were designed and presented. Finally, offshore tests were carried out and the power performance of the rotor was obtained and compared with the published literatures, and the results showed that the power coefficient was satisfactory, which agrees with the theoretical predictions. 相似文献
4.
We recently showed the advantage of using a numerical system to extract energy from tidal currents by developing a new twin-turbine model (Li and Calisal, 2010a). Encouraged by this result, we decided to use this model to study another important characteristic of the turbine system, torque fluctuation. This effort is summarized in this paper. The torque fluctuation is expected to reduce the fatigue life of tidal current turbines, though potentially it also may deteriorate the power quality of tidal current turbines. In this paper, after reviewing the twin-turbine model, we use it to predict the torque fluctuation of the system with the same configurations as we used to study the power output in Li and Calisal (2010a). Specifically, we investigate the torque fluctuation of twin-turbine systems with various turbine parameters (e.g., relative distance between two turbines and incoming flow angle) and operational condition (e.g., tip speed ratio). The results suggest that the torque of an optimally configured twin-turbine system fluctuates much less than that of the corresponding stand-alone turbine, under the same operating conditions. We then extensively compare the hydrodynamic interaction’s impact on the torque fluctuation and the power output of the system. We conclude that the hydrodynamic interactions pose more constructive impacts on the torque fluctuation than on the power output. The findings indicate that the optimally configured counter-rotating system should be a side-by-side system, and that the optimally configured co-rotating system should have the downstream turbine partially in the wake of the upstream turbine depending on the detailed configuration of the turbines. Furthermore, one must balance the optimal torque fluctuation against the optimal power output. 相似文献
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Under real sea conditions, the hydrodynamic performance of floating vertical-axis tidal current turbines is affected by waves and currents. The wave circular frequency is a significant factor in determining the frequencies of the wave-induced motion responses of turbines. In this study, the ANSYS-CFX software (manufacturer: ANSYS Inc., Pittsburgh, Pennsylvania, United States) is used to analyse the hydrodynamic performance of a vertical-axis turbine for different yawing frequencies and to study how the yawing frequencies affect the main hydrodynamic coefficients of the turbine, including the power coefficient, thrust coefficient, lateral force coefficient, and yawing moment coefficient. The time-varying curves obtained from the CFX software are fitted using the least-squares method; the damping and added mass coefficients are then calculated to analyse the influence of different yawing frequencies. The simulation results demonstrate that when analysing non-yawing turbines rotating under constant inflow, the main hydrodynamic coefficient time-varying curves of yawing turbines exhibit an additional fluctuation. Furthermore, the amplitude is positively correlated with the yawing frequency, and the oscillation amplitudes also increase with increasing yawing frequency; however, the average values of the hydrodynamic coefficients (except the power coefficient) are only weakly influenced by yawing motion. The power coefficient under yawing motion is lower than that under non-yawing motion, which means that yawing motion will cause the annual energy production of a turbine to decrease. The fitting results show that the damping term and the added mass term exert effects of the same level on the loads and moments of vertical-axis turbines under yawing motion. The results of this study can facilitate the study of the motion response of floating vertical-axis tidal current turbine systems in waves. 相似文献
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The performance of a Wells turbine with various non-uniform tip clearances was investigated using computational fluid dynamics (CFD). The investigation was performed on numerical models of a NACA0020 blade profile under steady flow conditions. The performance of turbines with uniform and non-uniform tip clearances was compared. The results were also compared with experimental results in literature. It was shown that the performance of turbine with non-uniform tip clearance is similar with that of turbine with uniform one in terms of torque coefficient, input power coefficient, and efficiency. However, the turbine with non-uniform tip clearance seems to have a preferable overall performance. An investigation on the flow-field around the turbine blade was performed in order to explain the phenomena. 相似文献
7.
潮流能发电装置支撑结构对水轮机水动力学性能影响研究 总被引：1，自引：0，他引：1
水平轴潮流能水轮机在工作过程中,由于支撑结构的存在,会使水轮机周围流场中的潮流流向、流速等参数发生不同程度的改变,进而影响水轮机的性能和发电装置的稳定性。为了研究支撑结构对水轮机水动力学性能的影响规律,以某100 k W单立柱座底式潮流能发电装置的支撑结构为研究对象,采用CFD方法,分别在正、反向来流时采用不同支撑结构的共六种工况下,对潮流能水轮机模型的获能和受力进行数值模拟。通过水槽模型试验,验证数值模拟的可靠性。研究结果表明:支撑结构对水轮机的水动力学性能的影响不容忽视,针对所研究的支撑结构,在正向来流时水轮机的获能系数降幅约30%,轴向力系数降幅约28%;反向来流时的降幅更大,分别约为63%和41%。 相似文献
8.
Numerical and Experimental Study of the 3D Effect on Connecting Arm of Vertical Axis Tidal Current Turbine 
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下载免费PDF全文 Vertical axis tidal current turbine is a promising device to extract energy from ocean current. One of the important components of the turbine is the connecting arm, which can bring about a significant effect on the pressure distribution along the span of the turbine blade, herein we call it 3D effect. However, so far the effect is rarely reported in the research, moreover, in numerical simulation. In the present study, a 3D numerical model of the turbine with the connecting arm was developed by using FLUENT software compiling the UDF (User Defined Function) command. The simulation results show that the pressure distribution along the span of blade with the connecting arm model is significantly different from those without the connecting arm. To facilitate the validation of numerical model, the laboratory experiment has been carried out by using three different types of NACA aerofoil connecting arm and circle section connecting arm. And results show that the turbine with NACA0012 connecting arm has the best start-up performance which is 0.346 m/s and the peak point of power conversion coefficient is around 0.33. A further study has been performed and a conclusion is drawn that the aerofoil and thickness of connecting arm are the most important factors on the power conversion coefficient of the vertical axis tidal current turbine. 相似文献
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在多风机风电场中,通过主动调节上游风机的偏航角度,抑制上游风机尾流对下游风机的影响,减少风力机机组之间的尾流相互干扰,以达到提高整个风电场效率的目的。采用基于开源平台Open FOAM自主开发的FOWT-UALM-SJTU求解器中风电场求解模块ALMWindFarmFoam,将致动线模型与CFD方法相结合,利用大涡模拟(LES)计算研究当上游风机处于不同偏航角度时,两风机之间的复杂尾流干扰效应。对比分析偏航角度改变时,上下游风机气动功率的输出特性,尾流速度变化以及风机的尾涡结构。数值模拟结果表明:在上下游风机沿流向方向距离保持不变的情况下,随着上游风机偏航角度的变化,上下游风机的尾流干扰现象以及下游风机的入流条件会发生明显改变,并会对下游风机的气动功率输出以及两风机风电场的整体流场产生显著影响。 相似文献
10.
Stephen R. Turnock Alexander B. Phillips Joe Banks Rachel Nicholls-Lee 《Ocean Engineering》2011,38(11-12):1300-1307
An improved method is developed to couple an inner domain solution of the blade element momentum theory with an outer domain solution of the Reynolds averaged Navier Stokes equations for evaluating performance of tidal current turbines. A mesh sensitivity study shows that a mesh of at least 6 M cells with at least 40% of these within the turbine wake is required to ensure satisfactory convergence of the velocity deficit. In addition to the usually applied axial momentum source terms, angular momentum and turbulence intensity source terms are shown to be required to model the near wake evolution. Three different lateral turbine spacing of 2, 4 and 6 turbine diameters are used to demonstrate the influence of the effective channel blockage on the velocity distribution in the turbine bypass region, the rate of spread of the wake and the recovery of velocity distribution. A final study shows that for a fixed number of turbines minimising the lateral spacing within each row, with a small number of staggered rows spaced as longitudinally as far apart as practical, is the most effective strategy for energy capture. 相似文献
11.
《Ocean Engineering》2010,37(7):627-637
Recent interest in the tidal current industry has driven development of the prototype from the stand-alone turbine to the twin-turbine system. In this paper, we develop a numerical model to systematically analyze the relationship between the power output and the configuration of a twin-turbine system. First, we present the design principle of the twin-turbine system. We then develop the numerical model for simulating the operation of the system, and validate the model by conducting towing tank experimental tests. We then use the model to predict the power output of the system. The results of this study show that the total power output of a twin-turbine system with optimal layout can be about 25% higher than two times that of a stand-alone turbine. We also discuss the hydrodynamic interaction between the two turbines under different configurations of the system. We conclude that the optimally configured counter-rotating system should be a side-by-side system, and that the optimally configured co-rotating system should have the downstream turbine partially in the wake of the upstream turbine, depending on the detailed configuration of the turbine. 相似文献
12.
A novel tidal turbine with winglet is given, and the influences of winglets on the hydrodynamic performance of horizontal axis current turbines (HACT) are investigated. The incompressible Reynolds-Averaged Navier–Stokes (RANS) Equations with the k − ω shear stress transport (SST) turbulence model are solved. Two HACTs with the winglet that bent towards the pressure side or suction side are designed as the conceptual designs. The pressure distribution and tip vortices are analyzed and compared to investigate the effect of the winglets. Based on the simulation results, the parameter study of the winglet is performed to investigate the effect of length, tip chord and cant angle on the hydrodynamic performance. Results demonstrate that the numerical simulation shows good agreement with the experimental data. The performance of HACT could be improved only when the winglet bends towards the suction side. At the optimum tip speed ratio (TSR), the best design can achieve 4.66% power increase rate compared with that of the baseline turbine. The proper length, tip chord and cant angle of the winglet could improve power at the whole conditions. 相似文献
13.
潮流发电水轮机基于动量定理的性能计算方法研究 总被引：2，自引：0，他引：2
以潮流发电水轮机的设计为研究背景,分析和总结了基于动量定理方法的四种流管模型(单盘面-单流管模型、双盘面-单流管模型、单盘面-多流管模型和双盘面-多流管模型)在竖轴变攻角水轮机的水动力性能计算中的应用,特别是能量利用率预报方面的应用。说明基于动量定理的模型在求竖轴变攻角潮流发电水轮机的水动力性能方面,能够预报一些定性特性和总体趋势,为水轮机的设计和计算提供一种初步方法。 相似文献
14.
基于致动线模型的错列式两风机尾流场数值模拟 总被引：1，自引：1，他引：0
风电场中风机之间存在十分复杂尾流相互干扰现象,尾流相互干扰效应对风机的功率输出、叶片载荷等产生十分显著的影响。采用致动线模型以及计算流体力学方法,研究两风机之间的复杂尾流干扰效应。在保持两风机纵向间距一样的情况下,考虑两风机在不同横向间距下,数值模拟两风机的部分尾流相互干扰现象,分析两风机的气动功率输出特性、尾流速度变化特性、风轮平面附近轴向诱导因子分布特性,尾涡结构以及尾流干扰效应。数值模拟结果表明:在上下游风机在沿着流向方向距离保持不变的情况下,随着横向间距的变化,上下游风机的尾流存在十分复杂的尾流相互干扰效应,对下游风机的气动功率输出以及两风机风电场的整体流场产生了显著的影响。 相似文献
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在风机大尺度化与风场大型化的趋势下，如何通过合适的控制策略以降低尾流损失成为关键问题。以包括30台NREL-5MW风机并采用5行6列平行四边形布置方式的小型风场为研究对象，基于显示尾流模型，以各风机偏航角度为优化参数，风场总功率为目标函数，使用粒子群优化算法对比分析了偏航控制对不同风速、风向、湍流强度下的风场性能提升效果。结果表明，偏航控制优化可在风向与风机行或列方向平行时发挥明显效果，当风机行列间距为4倍风轮直径且湍流强度为5%时，在不同风速下偏航控制可分别将风场总体发电量提升15%~20%，但对于布置间距大于7倍风轮直径或湍流强度高于15%时的风场，其作用十分有限，总体发电量提升在5%以内。 相似文献
18.
In consideration of the resource wasted by unreasonable layout scheme of tidal current turbines, which would influence the ratio of cost and power output, particle swarm optimization algorithm is introduced and improved in the paper. In order to solve the problem of optimal array of tidal turbines, the discrete particle swarm optimization (DPSO) algorithm has been performed by re-defining the updating strategies of particles’ velocity and position. This paper analyzes the optimization problem of micrositing of tidal current turbines by adjusting each turbine’s position, where the maximum value of total electric power is obtained at the maximum speed in the flood tide and ebb tide. Firstly, the best installed turbine number is generated by maximizing the output energy in the given tidal farm by the Farm/Flux and empirical method. Secondly, considering the wake effect, the reasonable distance between turbines, and the tidal velocities influencing factors in the tidal farm, Jensen wake model and elliptic distribution model are selected for the turbines’ total generating capacity calculation at the maximum speed in the flood tide and ebb tide. Finally, the total generating capacity, regarded as objective function, is calculated in the final simulation, thus the DPSO could guide the individuals to the feasible area and optimal position. The results have been concluded that the optimization algorithm, which increased 6.19% more recourse output than experience method, can be thought as a good tool for engineering design of tidal energy demonstration. 相似文献
19.
随着海上风电产业的快速发展,大型浮式风机逐渐从概念设计走向工程应用,但仍面临较大的挑战。一方面,在风、浪等环境载荷的作用下,浮式风机的气动载荷和水动力响应之间存在明显的相互干扰作用;另一方面,风力机大型化使得叶片细、长、薄的特点愈发突出,叶片柔性变形十分显著,这会影响到浮式风机的耦合性能。基于两相流CFD求解器naoe-FOAM-SJTU,结合弹性致动线模型和等效梁理论,建立了浮式风机气动—水动—气弹性耦合响应计算模型,并对规则波和剪切风作用下Spar型浮式风机的气动—水动—气弹性耦合响应进行了数值模拟分析。结果表明,风力机气动载荷使得叶片挥舞变形十分显著,而叶片的扭转变形会明显降低风力机的气动载荷。此外,风力机气动载荷会增大浮式平台的纵荡位移和纵摇角,同时,浮式平台运动响应会导致风力机气动载荷产生大幅度周期性变化。进一步地,叶片结构变形响应会使得浮式风机尾流场的速度损失和湍动能有所降低。 相似文献
20.
Based on blade element momentum theory and generator characteristic test, a dynamic simulation model of 150 kW horizontal-axis tidal current turbine was established. The matching of the dynamic characteristics between the turbine and generator under various current velocities is studied, and the influence of the pitch angle on the matching is analyzed. For the problem of maximum power output in case of low current speed and limiting power in high current speed, the relation between optimal pitch angle and output power is analyzed. On the basis of dynamic characteristic analysis, the variable pitch control strategy is developed. The performance of the turbine under various tidal conditions is simulated. The research results show that the designed controller enables the turbine to operate efficiently under the condition of low current speed, and achieve the goal of limited power at high current speed. 相似文献