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Smart helicopter rotor with active blade tips.

机译：带有主动式桨尖的智能直升机旋翼。

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The smart active blade tip (SABT) rotor is an on-blade rotor vibration reduction system, incorporating active blade tips that can be independently pitched with respect to the main blade.; The active blade tip rotor development included an experimental test program culminating in a Mach scale hover test, and a parallel development of a coupled, elastic actuator and rotor blade analysis for preliminary design studies and hover performance prediction.; The experimental testing focussed on a small scale rotor on a bearingless Bell-412 hub. The fabricated Mach-scale active-tip rotor has a diameter of 1.524 m, a blade chord of 76.2 mm and incorporated a 10% span active tip. The nominal operating speed is 2000 rpm, giving a tip Mach number of 0.47. The blade tips are driven by a novel piezo-induced bending-torsion coupled actuator beam, located spanwise in the hollow mid-cell of the main rotor blade.; In hover at 2000 rpm, at 2 deg collective, and for an actuation of 125 Vrms, the measured blade tip deflection at the first four rotor harmonics is between ±1.7 and ±2.8 deg, increasing to ±5.3 deg at 5/rev with resonant amplification. The corresponding oscillatory amplitude of the rotor thrust coefficient is between 0.7 · 10−3 and 1.3 · 10−1 at the first four rotor harmonics, increasing to 2.1 · 10−3 at 5/rev.; In general, the experimental blade tip frequency response and corresponding rotor thrust response are well captured by the analysis. The flexbeam root flap bending moment is predicted in trend, but is significantly over-estimated.; The blade tips did not deflect as expected at high collective settings, because of the blade tip shaft locking up in the bearing. This is caused by the high flap bending moment on the blade tip shaft. Redesign of the blade tip shaft assembly and bearing support is identified as the primary design improvement for future research.; The active blade tip rotor was also used as a testbed for the evaluation of an adaptive neural-network based control algorithm. Effective background vibration reduction of an intentional 1/rev hover imbalance was demonstrated. The control algorithm also showed the capability to generate desired multi-frequency control loads on the hub, based on artificial signal injection into the vibration measurement.; The research program demonstrates the technical feasibility of the active blade tip concept for vibration reduction and warrants further investigation in terms of closed loop forward flight tests in the windtunnel and full scale design studies.
机译：智能主动叶片尖端（SABT）转子是一种叶片上转子减振系统，结合了可以相对于主叶片独立变桨的主动叶片尖端。主动式叶尖转子的开发包括以马赫规模悬停测试为最终的实验测试程序，以及为初步设计研究和悬停性能预测而进行的耦合弹性致动器和转子叶片分析的并行开发。实验测试的重点是无轴承Bell-412轮毂上的小型转子。所制造的马赫规模的主动式尖端转子的直径为1.524 m，叶片弦长为76.2 mm，并装有跨度为10％的主动式尖端。标称运行速度为2000 rpm，尖端马赫数为0.47。叶片尖端由新颖的压电感应的弯曲扭转耦合的致动器梁驱动，该致动器梁沿翼展方向位于主转子叶片的中空单元中。在以2000 rpm的速度悬停时，在2度共同作用下，并且对于125 V 的致动，在前四个转子谐波处测得的叶尖偏转在±1.7到±2.8度之间，增加到± 5.3 deg在5 / rev具有共振放大。在前四个转子谐波处，转子推力系数的相应振荡幅度在0.7·10 -3 和1.3·10 -1 之间，增加到2.1·10 −3 以5 / rev .;通常，通过分析可以很好地捕获实验叶片尖端的频率响应和相应的转子推力响应。弯曲梁根瓣的弯矩在趋势上可以预测，但明显被高估了。叶片尖端未在较高的总体设置下发生偏斜，因为叶片尖端轴锁定在轴承中。这是由于叶片尖端轴上的襟翼弯曲力矩高而引起的。刀尖轴组件和轴承支撑的重新设计被认为是未来研究的主要设计改进。主动式叶尖转子也用作测试床，用于评估基于自适应神经网络的控制算法。事实证明，有效减少了1 / rev悬停不平衡的背景振动。该控制算法还显示了基于将人工信号注入振动测量中而在轮毂上生成所需的多频控制负载的能力。该研究计划证明了主动叶片尖端概念在降低振动方面的技术可行性，并需要对风洞中的闭环前向飞行测试和全面设计研究进行进一步研究。

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