An investigation of unsteady 3-D effects on trailing edge flaps
An investigation of unsteady 3-D effects on trailing edge flaps
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DOI：
10.5194/wes-2-241-2017
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发表时间：
2016-12
期刊：
影响因子：
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通讯作者：
E. Jost;A. Fischer;G. Bangga;T. Lutz;E. Krämer
中科院分区：
文献类型：
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作者：
E. Jost;A. Fischer;G. Bangga;T. Lutz;E. Krämer
抽象的。采用计算流体力学(CFD)方法研究了非定常三维气动效应对带尾缘襟翼的风力机叶片的影响。在DTU 10 MW转子上模拟了叶片半径为70%~80%的10%弦长变形襟翼的简谐振动。偏转频率在1到6p的范围内变化。为了量化三维影响，旋翼模拟与二维翼型计算和Theodorsen的二维理论进行了比较。研究发现，三维旋翼襟翼的偏转会导致复杂的尾迹发展和诱导，从而影响叶片大部分部位的载荷。尤其是尾迹附近的旋翼，其尾涡和脱落涡结构显示出很大的影响。尾涡是一种三维现象，它是由叶展上束缚环流的梯度引起的。雨滴涡度源于时间边界环流梯度，因此在2-D中也很明显。两者都导致幅度减小和脱落涡量，以及相对于襟翼部分中的偏转信号的升力响应的滞后。与二维翼型相比，在三维旋翼上观察到了更大的振幅减小和较小的滞后。然而，襟翼附近的叶片部分受到相反的冲击，因此部分补偿了襟翼部分尾涡相对于整体载荷的负面影响。与三维旋翼的稳态襟翼挠度的比较表明，动态流入效应的影响很大。
Abstract. The present study investigates the impact of unsteady 3-D aerodynamic effects on a wind turbine blade with trailing edge flap by means of computational fluid dynamics (CFD). Harmonic oscillations are simulated on the DTU 10 MW rotor with a morphing flap of 10 % chord extent ranging from 70 to 80 % blade radius. The deflection frequency is varied in the range between 1 and 6 p. To quantify 3-D effects, rotor simulations are compared to 2-D airfoil computations and the 2-D theory by Theodorsen. It was found that the deflection of the flap on the 3-D rotor causes a complex wake development and induction which influences the loads over large parts of the blade. In particular, the rotor near wake with its trailing and shed vortex structures revealed a great impact. Trailing vorticity, a 3-D phenomenon, is caused by the gradient of bound circulation along the blade span. Shed vorticity originates from the temporal bound circulation gradient and is thus also apparent in 2-D. Both lead to an amplitude reduction and shed vorticity additionally to a hysteresis of the lift response with regard to the deflection signal in the flap section. A greater amplitude reduction and a less pronounced hysteresis is observed on the 3-D rotor compared to the 2-D airfoil case. Blade sections neighboring the flap experience, however, an opposing impact and hence partly compensate for the negative effect of trailing vortices in the flap section with respect to integral loads. Comparisons to steady flap deflections at the 3-D rotor revealed the high influence of dynamic inflow effects.