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Flow control on helicopter rotors using active gurney flaps

机译:使用有源格尼襟翼控制直升机旋翼的流量

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摘要

This thesis presents closed loop control of active Gurney flaps on rotors. Firstly, it builds on the Helicopter Multi-Block 2 CFD solver of the University of Liverpool and demonstrates the implementation and use of Gurney flaps on wings, and rotors. The idea is to flag any cell face within the computational mesh with a solid, no slip boundary condition. Hence the infinitely thin Gurney can be approximated by “blocking cells” in the mesh. Comparison between thick Gurney flaps and infinitely thin Gurneys showed no difference on the integrated loads, the same flow structure was captured and the same vortices were identified ahead and behind the Gurney. The results presented for various test cases suggest that the method is simple and efficient and it can therefore be used for routine analysis of rotors with Gurney flaps. The potential effect of a Gurney flap all over the performance of the W3-Sokol rotor blade in hover was studied next. A rigid blade was first considered and the calculations were conducted at several thrust settings. The Gurney flap was extended from 46%R to 66%R and it was located at the trailing edge of the main rotor blade. Four different sizes of Gurney flaps were studied, 2%, 1%, 0.5% and 0.3% of the chord, and the biggest flap proved to be the most effective. A second study considered elastic blades with and without the Gurney flap. The results were trimmed at the same thrust values as the rigid blade and indicate an increase of aerodynamic performance when the Gurney flap is used, especially for high thrust cases. Moreover, the performance of the W3-Sokol rotor in forward flight with and without Gurney flap was tested. Rigid and elastic blade models were considered and calculations were guided using flight test data. The Gurney flap was extended from 40%R to 65%R, while the size of the Gurney was selected to be 2% of the chord based on the hover study. All results were trimmed to the same thrust as flight tests. The harmonic analysis of the flight test data proved to be a useful tool for identifying vibrations on the rotor caused by stall at the retreating side, and a carefully designed Gurney flap and actuation schedule were essential to alleviate the effects of flow separation. The last part of the thesis is dedicated to a closed loop actuation of the Gurney flap based on the leading edge pressure divergence criterion. The effect of the Gurney flap on the trimming of a full helicopter model, as well as the handling qualities of the rotorcraft were investigated. To the author’s knowledge this is the first attempt to study the effect of active Gurney flaps on elastic rotors with 3D CFD in a closed loop control for retreating blade stall alleviation and hover performance enhancement. The idea is that Gurney will stay deployed during the hover and it will be actuated based on the forward flight demands in order to enhance the rotorcraft capabilities.
机译:本文提出了转子上有源格尼襟翼的闭环控制。首先,它基于利物浦大学的直升机Multi-Block 2 CFD解算器,并演示了机翼和旋翼上的格尼襟翼的实现和使用。这个想法是用坚实的无滑动边界条件标记计算网格中的任何单元面。因此,无限薄的格尼可以通过网格中的“阻塞单元”来近似。较厚的格尼襟翼和无限薄的格尼之间的比较表明,在集成载荷上没有差异,捕获了相同的流动结构,并在格尼前后分别确定了相同的涡旋。针对各种测试案例提出的结果表明,该方法简单有效,因此可以用于带有格尼襟翼的转子的常规分析。接下来研究格尼襟翼对W3-Sokol旋翼桨叶悬停性能的潜在影响。首先考虑了刚性叶片,并在几种推力设置下进行了计算。格尼襟翼从46%R扩展到66%R,位于主旋翼叶片的后缘。研究了四种不同尺寸的格尼襟翼,分别占弦的2%,1%,0.5%和0.3%,最大的襟翼被证明是最有效的。第二项研究考虑了带或不带格尼襟翼的弹性叶片。在与刚性叶片相同的推力值下修整结果,表明使用格尼襟翼时,尤其是在大推力情况下,空气动力学性能有所提高。此外,测试了W3-Sokol旋翼在有和没有格尼襟翼的情况下在向前飞行中的性能。考虑了刚性和弹性叶片模型,并使用飞行测试数据指导了计算。根据悬停研究,格尼襟翼从40%R扩展到65%R,而格尼的大小选择为弦的2%。所有结果均调整为与飞行测试相同的推力。飞行测试数据的谐波分析被证明是识别后退侧失速引起的转子振动的有用工具,精心设计的格尼襟翼和启动时间表对于减轻流分离的影响至关重要。本文的最后一部分致力于根据前缘压力发散准则对格尼襟翼进行闭环驱动。研究了格尼襟翼对完整直升机模型的修剪效果以及旋翼飞机的操纵质量。据作者所知,这是首次尝试在闭环控制中使用3D CFD研究主动格尼襟翼对弹性转子的影响,以减轻叶片失速并提高悬停性能。这个想法是,格尼将在悬停期间保持部署状态,并将根据向前飞行的需求进行驱动,以增强旋翼飞机的能力。

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  • 作者

    Pastrikakis V;

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  • 年度 2000
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  • 原文格式 PDF
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