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中文核心期刊

半潜式海上浮式风机气动阻尼特性研究

STUDY ON AERODYNAMIC DAMPING OF SEMI-SUBMERSIBLE FLOATING WIND TURBINES

  • 摘要: 由于海上漂浮式风机具有较大的支撑平台运动,气动阻尼效应对海上漂浮式风机的运动响应带来了重要的影响, 日渐受到相关国内外学者的关注. 为了研究海上浮式风机的气动阻尼特性,本文推导了海上浮式风机气动阻尼力的数学模型,并借助模型实验和数值计算的方法,研究了半潜式海上浮式风机的气动阻尼特性及其作用规律. 结果表明,浮式风机的风轮旋转时的气动阻尼比风轮非旋转状态时更加明显;在作业工况下,气动阻尼对半潜式浮式风机平台的纵荡、纵摇、机舱的运动有明显的抑制作用,且主要体现为对半潜式浮式风机的平台运动固有频率响应的抑制作用,对波频范围的平台运动作用甚微. 其变化规律与风速大小、波浪载荷等有关,在风机的额定工况之前,气动阻尼通常与风速呈正相关关系,但是增长率有逐渐减小的趋势;在控制系统作用下,当入流风速接近或超过风机额定风速时,容易出现气动负阻尼现象,反而进一步强化浮式风机的运动响应,此时通过降低变桨距控制器的比例系数,即降低变桨距控制器的灵敏度,有助于增加海上浮式风机的气动阻尼效果,并且在一定程度上减缓负的气动阻尼的发生,改善海上浮式风机的运动响应.

     

    Abstract: Aerodynamic damping effect has an impact on dynamic responses of an offshore floating wind turbine induced by the greater platform motion of an offshore floating wind turbine, which has attracted increasing attention by Chinese and foreign scholars recently. In order to investigate aerodynamic damping effects on an offshore floating wind turbine, a mathematical model of the aerodynamic damping of offshore floating wind turbines is deduced, and then the study on the characteristics of the aerodynamic damping effect of offshore floating wind turbines and the law of the aerodynamic damping effect of offshore floating wind turbines are conducted using model experimental results and simulation results in the paper. The results show that the aerodynamic damping effect of a semi-submersible offshore floating wind turbine in operation condition is greater than that in parked condition. Aerodynamic damping effect restrains the platform surge motion, the platform pitch motion and the nacelle motion of a semi-submersible offshore floating wind turbine in the operation condition. In frequency-domain, aerodynamic damping effect has an impact on motion at its inherent frequency but has little effect on the motion in wave-energy frequency range relating to the wind speed and wave state. The aerodynamic effect of offshore floating wind turbines is in positive correlation with the wind speed, but the gradient of aerodynamic damping effect of a semi-submersible offshore floating wind turbine gradually decreases with the wind speed below the rated wind speed. When the wind speed reach or exceed the rated wind speed, there could be negative damping effect on an offshore floating wind turbine with a blade-pitch-controller. It is found that decreasing proportionality coefficient of the blade-pitch-controller can reduce the sensitivity of the blade-pitch-controller so as to mitigate the negative aerodynamic damping of a semi-submersible offshore floating wind turbine and improve the motion performances of a semi-submersible offshore floating wind turbine to some extent.

     

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