Aeroelastic Loads and Stability of Swept-Tip Hingeless Tiltrotors Toward 400 knots Flutter-Free Cruise

Seyhan Gul, A. Datta
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Abstract

A hingeless hub tiltrotor with swept-tip blades was examined comprehensively with a new rotorcraft aeromechanics solver developed at the University of Maryland. The solver was verified with hypothetical U.S. government results and validated with Boeing M222 test data from 1972. A 20◦ sweep back from 80%R increased instability speed to 395 knots, an improvement of 70 knots. The key mechanism is the aerodynamic center shift. The trade-off is the increase in control system loads. Fundamental understanding of the physics is provided. Air resonance emerged as the critical phenomenon, not whirl flutter. Predictions in powered mode is necessary. At least first rotor flap, lag, and torsion modes need to be included. Rotor aerodynamics should use airfoil tables; wing aerodynamics is not important for air resonance. Analysis shows high speed flight is achievable with 13.5% wings but systematic wind tunnel tests with modern equipment is necessary for further validation.
400节无颤振巡航时后掠无铰倾转旋翼的气动弹性载荷和稳定性
利用美国马里兰大学开发的新型旋翼机气动力学求解器,对一种带后掠叶的无铰轮毂倾转旋翼机进行了全面研究。求解器通过假设的美国政府结果和1972年的波音M222测试数据进行了验证。20◦后掠从80%R增加不稳定速度到395节,提高70节。关键的机理是气动中心移位。代价是控制系统负载的增加。提供了对物理学的基本理解。空气共振作为临界现象出现,而不是旋转颤振。在供电模式下进行预测是必要的。至少第一旋翼襟翼,滞后和扭转模式需要包括在内。转子空气动力学应使用翼型表;机翼空气动力学对空气共振并不重要。分析表明,13.5%的机翼可以实现高速飞行,但需要用现代设备进行系统的风洞试验来进一步验证。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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