随机风况下襟翼闭环载荷控制的数值研究

Numerical Study of the Closed Loop Load Control of Trailing Edge Flap Under the Random Wind Condition

柔性襟翼在减缓风力机叶片极限与疲劳载荷方面一直备受关注。为研究柔性襟翼在非稳定入流时的减载能力,以二维翼型S809为基础翼型,CFD计算获取的翼型升力为反馈信号,利用ANSYS Fluent 17.0及其用户自定义端口,建立了襟翼闭环载荷控制系统。研究了襟翼在来流随机变化时减缓翼型升力波动的效果,并分析了襟翼最大偏转速度与系统延迟时间对控制效果的影响。结果表明:襟翼控制后的翼型升力波动标准差减小了99%,进一步提高最大偏转速度后,仅在变化较急剧的峰值处略有区别;较大的延迟时间导致升力在波动方式与范围上都有别于无延迟与小延迟,不利于襟翼对载荷波动的减缓。

As the ability to mitigate the limit and fatigue load of wind turbine blades, the trailing edge flap receives much concerns. In order to investigate the ability of flexible flap to mitigate the load on blade when the inflow is unsteady, the 2D Reynolds Averaged Navier-Stokes solver with Transition SST （T-SST） turbulence model was employed to calculate the lift of $809 airfoil. As a feedback signal, the deviation between lift and given lift drives the flap to adjust the lift to be closed to the given lift. The variation of wind speed is random, and the effects of maximum flap deflection speeds and system delay times on control were analyzed. The results show that when the deflections of flap is applied, the standard deviation of airfoil lift is reduced by 99%; When the maximum flap deflection speed is increased, the improvements of control effect are small except at the peak of lift. The characteristics and scopes of lift fluctuation with large delay times of flap control are different from that with small delay, and the difference is adverse to the mitigations of lift fluctuation.