Flutter Suppression for High Aspect Ratio Flexible Wings Using Microflaps-猫眼课题宝

DOI：

10.2514/6.2002-1717

发表时间：

2002-04

期刊：

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其他

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作者：

Hak-Tae Lee;I. Kroo;Stefan R. Bieniawski

微型后缘效应器是一种小型襟翼(通常为1%到5%的弦)，其偏转角度可达90度。由于体积小，这些设备提供了高带宽控制的机会。本研究考虑使用多个这样的操纵面来提高大展弦比柔性机翼的颤振速度。有限元板模型用于模拟结构动力学，非定常面元方法提供气动载荷。颤振试验结果与数值稳定性分析结果吻合较好。在后缘用单板单元模拟，在其配置点采用不同的边界条件。尽管尘螨具有复杂的粘性空气动力学，但面板模型被证明能够很好地模拟稳态和非定常行为。由于其非线性特性，这些效应器用于控制是复杂的。由于执行机构仅在大偏转角度下有效，因此仅在以下三个位置之一进行偏转：向上、向下和空档。利用数值优化方法设计了一种非线性反馈控制器。格尼襟翼是一种小襟翼(通常为1%∼5%弦)，用于增加翼型部分的最大升力。它是由Robert Liebeck和Dan Gurney在1960‘S开发并应用于赛车，尽管类似的设备也被用于二战飞机上，如P-38∗博士生，航空航天系，AIAA学生成员†教授，AIAA研究员‡博士生，航空和宇航系，AIAA成员版权所有c？2002。由美国航空航天研究所出版，经许可。和F8-F。在带有Gurney襟翼的单段翼型和多段翼型上进行了大量的风洞试验和数值计算。这些研究证实，尽管Gurney襟翼的尺寸很小，但挠度接近90度的Gurney襟翼可以增加最大升力和在给定攻角下产生的升力。利贝克解释了这种效应，这种效应是由襟翼上游的一小段分离流动产生的，下游有两个反向旋转的涡旋，有效地改变了后缘库塔条件。通过流动可视化和CFD模拟验证了这对于时间平均流动的正确性。在目前的工作中，我们考虑使用类似于Gurney襟翼的装置，不是为了增加最大升力，而是为了提供高带宽、稳健的控制。微型尾缘效应器是位于尾缘或靠近尾缘的小型可移动操纵面，它们被偏转到大角度，以产生可用于飞行控制或结构模式控制的控制力和力矩。目前的研究始于1998年，涉及使用这种致动器进行气动弹性控制。与传统的操纵面相比，MITE具有明显的优势：由于其体积小和惯性小，可以实现高带宽的驱动，使其能够用于飞行控制或更高频率的结构模式控制，同时显著降低功率要求。跨向变化和交错挠度可以产生横摇、俯仰和偏航力矩，以及对特定结构振型的控制。由于表面以离散的方式(向上、向下或中性)偏转，不需要主动伺服反馈，从而消除了精确、高速率的伺服致动器的成本，并使大量此类效应器能够以低成本制造。大量小而简单的效应器的使用也使系统具有容错性。通过设计一种能抑制柔性机翼颤振的主动控制系统，展示了蜂蜜在气动弹性控制中的应用。大展弦比柔性机翼备受关注

Miniature trailing edge effectors (MiTEs) are small flaps (typically 1% to 5% chord) actuated with deflection angles up to 90 degrees. Because of their small size, these devices provide the opportunity for high bandwidth control. The present study considers the use of many such control surfaces to increase the flutter speed of a high aspect ratio flexible wing. A finite element plate model is used to model the structural dynamics and an unsteady panel method provides the aerodynamic loads. Experimental flutter testing shows good agreement with the numerical stability analysis. The MiTE is modelled by a single panel element at the trailing edge with varying boundary conditions at its collocation point. In spite of the complex viscous aerodynamics of the MiTEs, the panel model proved to be adequate in simulating the steady and unsteady behavior. The use of these effectors for control is complicated by their nonlinear characteristics. Since the actuator is only effective at high deflection angles, it is only deflected in one of three positions: up, down, and neutral. The design of a nonlinear feedback controller has been performed using numerical optimization. Introduction The Gurney flap is a small (typically 1% ∼ 5% chord) flap used to increase the maximum lift of an airfoil section. It was developed and applied to racing cars by Robert Liebeck and Dan Gurney in 1960’s, although similar devices were employed in World War II aircraft such as the P-38 ∗Doctoral Candidate, Department of Aeronautics and Astronautics, AIAA Student Member †Professor, Department of Aeronautics and Astronautics, AIAA Fellow ‡Doctoral Candidate, Department of Aeronautics and Astronautics, AIAA Member Copyright c ©2002 by authors. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. and F8-F. Numerous wind-tunnel tests and numerical computations have been conducted on both single element and multi-element airfoils with Gurney flaps. These studies confirm that despite their small size, Gurney flaps with deflections near 90 degrees can increase maximum lift and the lift produced at a given angle of attack. Liebeck explained this effect, produced by a short region of separated flow directly upstream of the flap, with two counterrotating vortices downstream that effectively modify the trailing edge Kutta condition. This was verified to be correct for time averaged flow by flow visualizations and CFD simulations. In the present work, we consider the use of devices similar to Gurney flaps, not to increase maximum lift, but to provide high bandwidth, robust control. Miniature Trailing edge Effectors (MiTEs) are small movable control surfaces at or near the trailing edge, deflected to large angles to produce control forces and moments that may be used for flight control or structural mode control. The current study, begun in 1998, deals with the use of such actuators for aeroelastic control. MiTEs have distinct advantages over conventional control surfaces: High bandwidth actuation can be achieved due to their small size and inertia, enabling their use for flight control or for higher frequency structural mode control with significantly reduced power requirements. Spanwise variation and interdigitated deflections can produce rolling, pitching, and yawing moments, as well as the control of specific structural modes. Because the surfaces are deflected in a discrete manner (up, down, or neutral), no active servo-feedback is required, eliminating the expense of accurate, high-rate servo actuators and enabling a large number of these effectors to be fabricated at a low cost. The use of a large number of small, simple effectors also makes the system faulttolerant. The application of MiTEs for aeroelastic control is demonstrated here by designing an active control system that can suppress the flutter of a flexible wing. High aspect ratio flexible wings are of interest

Flutter Suppression for High Aspect Ratio Flexible Wings Using Microflaps

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