共查询到16条相似文献，搜索用时 140 毫秒
1.
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
2.
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
3.
潮流能发电机组在工作中,水轮机与潮流流向之间的偏航角对于机组的性能有较大影响。基于ANSYS Fluent软件采用SST k-ω湍流模型和滑移网格旋转模型对不同偏航角下水轮机进行数值模拟,分析偏航工况下水轮机性能及尾流场特性,并进行试验验证。结果表明:随着偏航角的增大,轴向力系数与功率系数降低,尾流场流速变化不对称现象趋于明显,同时造成周围流场湍流强度增大。 相似文献
4.
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
5.
浮式风机的平台作为支撑系统,其六自由度刚体运动响应决定上层风机的运动状态,也影响叶轮的环境载荷。叶轮的运动使周围流场变得复杂,叶片承受着非定常的气动载荷。研究中考虑叶片结构的运动,将基于定常流场的叶素动量理论用于局部叶素的气动分析,考虑偏航模型,充分模拟气流与叶轮的相互作用。在给定平台各个自由度运动下,计算叶轮气动参数,分析平台运动带来的影响,从入流速度方面探究引起气动载荷变化的本质原因。研究发现,叶轮气动性能和转动轴的方向有关,若平台运动改变转动轴方向,会引起气动载荷以多倍于叶轮旋转的频率发生周期变化,平台转动自由度的运动对叶轮气动性能影响显著。 相似文献
6.
基于自主研发的紧致插值曲线CIP (Constrained Interpolation Profile)方法数学模型,对均匀来流条件时不同运动自由度组合下的串列双圆柱涡激振动问题开展二维数值模拟。模型针对雷诺数Re=100,质量比m*=2的串列双圆柱涡激振动问题,选取上、下游圆柱不同运动自由度组合工况进行模拟。重点分析圆柱的升阻力系数、运动位移随折合速度Ur变化的响应。研究表明:当上游圆柱双自由度运动时,随着下游圆柱运动自由度的增加,下游圆柱对上游圆柱涡激振动响应的影响减弱;当下游圆柱双自由度运动时,随着上游圆柱运动自由度的增加,上游圆柱对下游圆柱涡激振动响应的影响变强。研究结果表明圆柱运动自由度组合形式对串列双圆柱涡激振动的影响不可忽略。 相似文献
7.
基于Fluent流体计算平台,运用大涡模拟方法对亚临界雷诺数Re=3900下“X”形排列五圆柱体结构群三维绕流特性进行研究,主要分析来流攻角α与间距比L/D两个关键参数对五圆柱体结构群的尾流区三维涡结构演化与流体力系数的影响,并揭示其内在流动互扰机理。研究表明:来流攻角和间距比的变化对五圆柱体结构群流动控制及互扰效应的影响显著。在小间距比工况下,观察到柱体群间隙区域内流体高速流动的现象,导致五圆柱体之间的互扰作用十分强烈。间隙流对中间圆柱体和下游圆柱体有较强的冲击作用,对其表面的流体力分布特性有显著的影响。另外,大间距比工况下,当α=0°与L/D≥5.0工况时,柱体群尾流效应强于其间隙流效应。当α=22.5°与L/D=7.0时,位于下游与中间处的圆柱体流体绕流特性存在较大差异。而当α=45°与L/D≥6.0时,位于上游与中间处的圆柱体尾流区均会产生正负交替的漩涡结构。 相似文献
8.
基于粒子图像测速技术(PIV)对小间距比比L/D=1.5工况下方形布置四圆柱在不同来流角角α(α=0°、15°、30°、45°)条件下的尾流流场特性进行了试验研究,分析了不同来流角度条件下四圆柱瞬时和时均尾流流场特征,获得了瞬时和时均速度矢量、涡量等值线、流线拓扑及雷诺应力分布随来流角度变化的规律。试验结果表明,来流角度对方形布置四圆柱尾流形态有显著影响。四圆柱瞬时尾流形态随来流角度增大可分为延伸体流动流态(α=0°)、尾流剪切层附着流态(α=15°、30°)及尾流剪切层共同脱落流态(α=45°)三种流态。当来流角度增大时,四圆柱下游断面平均流向速度分布由"W"形向"U"形转变,时均雷诺正应力及雷诺剪切应力等值线分布特征也会发生明显改变。 相似文献
9.
为研究潮流能水轮机尾流场流动特性及涡结构组成,基于DDES(Delayed Detached Eddy Simulation)模型对不同流速和转速的4种工况下水轮机尾流场进行数值模拟,并进一步探究其尾流场空间涡结构的变化特性。结果表明,水轮机的数值模拟结果与试验结果能够较好吻合。对比不同工况下的尾流场模拟结果可知:水轮机尾流区域流动复杂,延迟分离涡模拟方法能有效模拟水轮机旋转过程中产生的叶尖涡、叶尖脱落涡、轮毂涡等不同涡结构,并能完整观察到叶尖涡的产生、脱落、失稳、破碎过程。转速一定时,流速越大,叶尖脱落涡、轮毂涡的发展距离越远;流速一定时,转速越大,涡的发展距离越短。本文数值模拟计算结果可为实际海况中潮流能阵列水轮机的布局提供可靠依据。 相似文献
10.
对于海上浮式风机而言,由于受到剪切风、塔影效应、浮式基础运动等因素的共同影响,其气动载荷会更加复杂,因此如何准确快速地对海上风力机的气动性能进行预估显得尤为重要。基于速度势的非定常面元法理论,研究海上浮式风机气动载荷特性,编制了相关的计算程序。以NREL 5 MW风机为例,建立了叶片和尾流的三维数值模型,计算得到了不同风速下风机的输出功率以及叶片表面的压力分布,对比数据结果分析了该方法的可靠性。针对非定常流动,模拟了剪切风和塔影效应的作用,并重点分析了浮式基础运动对风机气动载荷的影响。研究表明,浮式基础的纵荡和纵摇会增加输出功率的波动幅值,艏摇运动会导致单个叶片上的气动载荷产生较大的波动,为浮式风机叶片控制提供了参考。 相似文献
11.
海上浮式风力机受风、浪、流等外部载荷影响,运营期间经常处于偏航工况,给风力机基础运动响应和锚泊载荷带来重要影响.基于经典叶素动量理论及势流理论,建立海上浮式风力机水—气动力耦合分析模型,对在非定常风、不规则波浪联合作用下,风力机偏航时基础运动响应及锚泊载荷等进行分析.研究发现,额定风速工况下,风力机偏航对平台纵荡和纵摇运动影响较大,偏航30°时纵荡和纵摇平均值比偏航0°时分别下降20.68％和37.36％,垂荡运动响应受风力机偏航影响较小;锚泊载荷变化趋势与平台运动及锚链布置有关,平台纵荡对锚泊载荷影响较大,偏航30°时锚链#1有效张力平均值比偏航0°时下降12.98％. 相似文献
12.
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
13.
《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
14.
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
15.
借助FAST软件对OC4半潜式浮式风机平台进行数值计算,分析了影响海上浮式风机平台首摇运动的一系列重要因素及其变化规律(如风向变化、浪向变化、陀螺力矩等)。研究了平台首摇运动所诱导的风机系统动力响应,发现浮式风机首摇运动不仅会加剧平台耦合运动响应,而且还会影响风机的气动性能和加剧锚泊张力波动。提出并探讨了几种减小海上浮式风机支撑平台首摇运动的方法。 相似文献
16.
Compared with bottom-fixed wind turbines,the supporting platform of a floating offshore wind turbine has a larger range of motion,so the gyroscopic effects of the system will be more obvious.In this paper,the mathematical analytic expression of the gyroscopic moment of a floating offshore wind turbine is derived firstly.Then,FAST software is utilized to perform a numerical analysis on the model of a spar-type horizontal axis floating offshore wind turbine,OC3-Hywind,so as to verify the correctness of the theoretical analytical formula and take an investigation on the characteristics of gyroscopic effect.It is found that the gyroscopic moment of the horizontal axis floating offshore wind turbine is essentially caused by the vector change of the rotating rotor,which may be due to the pitch or yaw motion of the floating platform or the yawing motion of the nacelle.When the rotor is rotating,the pitch motion of the platform mainly excites the gyroscopic moment in the rotor’s yaw direction,and the yaw motion of the platform largely excites the rotor’s gyroscopic moment in pitch direction,accordingly.The results show that the gyroscopic moment of the FOWT is roughly linearly related to the rotor’s inertia,the rotor speed,and the angular velocity of the platform motion. 相似文献