Passive Flow Control on Wind Turbine Rotors using Self-Adaptive Camber

达姆施塔特理工大学流体力学和空气动力学研究所开发了一种基于载荷的被动弯度控制概念，其特点是前缘和后缘襟翼机械耦合。脉动的流入条件导致了压力分布的改变，并在前缘襟翼上产生了一个力矩。力矩以前缘襟翼的顺时针旋转导致后缘襟翼的逆时针旋转的方式传递到后缘襟翼。由此产生的翼型曲面变化是完全被动的，不需要传感器或控制单元。其特性完全由流固耦合作用和耦合机构的特性决定。引入这一概念是为了缓解风力涡轮机转子叶片上的负载波动，总体目标是减少疲劳，提高转子耐久性和涡轮机寿命。在第一个资助期内，该概念的功能性在风洞中的二维流入条件下得到了验证。旋转系统中的流入条件与二维情况有根本的不同。科里奥利力和离心力促使水流径向改变方向。与二维情况相比，横向流动导致了压力分布的差异。这项建议旨在研究在这些改进的进气条件下的自适应弯度概念：具有自适应弯度机制的转子叶片将在PP2的研究涡轮上开发和试验。为了将横流的影响从虚力中分离出来，还将进行带有后掠翼的附加二维实验。这项建议的第二个目标是保证在与设计点不同的流动条件下的运行安全。这是通过提交一个具有自适应弯角机制的二维模型来实现的，以适应升力曲线非线性区域内的大迎角波动。

A load-dependent passive camber control concept featuring a mechanically coupled leading and trailing edge flap has been developed at the Institute of Fluid Mechanics and Aerodynamics at TU Darmstadt. Fluctuating inflow conditions lead to modified pressure distribution and induce a moment on the leading edge flap. The moment is transferred to the trailing edge flap in such a way that the clockwise rotation of the leading edge flap results in a counter clockwise rotation of the trailing edge flap. The resulting change in airfoil camber is completely passive and does not require sensors or control units. Its characteristics are determined solely by the fluid-structure interaction and the characteristics of the coupling mechanism. The concept is introduced for alleviating load fluctuations on wind turbine rotor blades with the overall goal of reducing fatigue and increasing rotor durability and turbine lifetime. During the first funding period, the functionality of the concept was proven under two dimensional inflow conditions in a wind tunnel.Inflow conditions in a rotating system differ fundamentally from the two dimensional case. Coriolis and Centrifugal forces provoke a radial redirection of the flow. The cross flow causes a difference of the pressure distribution compared to the two dimensional case. This proposal aims at investigating the adaptive camber concept under these modified inflow conditions: Rotor blades with adaptive camber mechanism will be developed and tested at the research turbine of PP2. In order to isolate the influence of crossflow from the fictitious forces, additional two-dimensional experiments with a swept wing will be performed. A second objective of this proposal is to guarantee operational safety at flow conditions differing from the design point. This is done by submitting a two-dimensional model with adaptive camber mechanism to high angle of attack fluctuations in the non-linear regime of the lift curve.