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首页> 外文期刊>Journal of Aircraft >CFD/CSD Prediction of Rotor Vibratory Loads in High-Speed Flight
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CFD/CSD Prediction of Rotor Vibratory Loads in High-Speed Flight

机译：高速飞行中转子振动载荷的CFD / CSD预测

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摘要

A computational fluid dynamics (CFD) model is coupled with a computational structural dynamics (CSD) model to improve prediction of helicopter rotor vibratory loads in high-speed flight. The two key problems of articulated rotor aeromechanics in high-speed flight—advancing blade lift phase, and underprediction of pitch link load—are satisfactorily resolved for the UH-60A rotor. The physics of aerodynamics and structural dynamics is first isolated from the coupled aeroelastic problem. The structural and aerodynamic models are validated separately using the UH-60A Airloads Program data. The key improvement provided by CFD over a lifting-line aerodynamic model is explained. The fundamental mechanisms behind rotor vibration at high speed are identified as: 1) large elastic twist deformations and 2) inboard wake interaction. The large twist deformations are driven by transonic pitching moments at the outboard stations. CFD captures 3-dimensional unsteady pitching moments at the outboard stations accurately. CFD/CSD coupling improves elastic twist deformations via accurate pitching moments and captures the vibratory lift harmonics correctly. At the outboard stations (86.5% radius out), the vibratory lift is dominated by elastic twist. At the inboard stations (67.5% and 77.5% radius), a refined wake model is necessary in addition to accurate twist. The peak-to-peak pitch link load and lower harmonic waveform are accurately captured. Discrepancies for higher harmonic torsion loads remain unresolved even with measured airloads. The predicted flap-bending moments show a phase shift of about 10 deg over the entire rotor azimuth. This error stems from 1, 2, and 3/rev lift. The 1/rev lift is unaffected by CFD/CSD coupling. The 2 and 3/rev lift are significantly improved but do not fully resolve the 2 and 3/rev bending moment error.
机译：计算流体动力学（CFD）模型与计算结构动力学（CSD）模型相结合，以改善高速飞行中直升机旋翼振动载荷的预测。对于UH-60A转子，令人满意地解决了高速飞行中的铰接式转子空气力学的两个关键问题-提前叶片升程阶段和对俯仰连杆负载的低估。空气动力学和结构动力学的物理学首先与耦合的空气弹性问题隔离开来。结构模型和空气动力学模型分别使用UH-60A空载计划数据进行验证。解释了CFD对提升线空气动力学模型的关键改进。转子高速振动背后的基本机制被确定为：1）大的弹性扭曲变形和2）舷内尾部相互作用。较大的扭曲变形是由舷外站的跨音速俯仰力矩驱动的。 CFD准确地捕获了舷外站的3维非稳态俯仰力矩。 CFD / CSD联轴器通过精确的俯仰力矩改善了弹性扭曲变形，并正确捕获了振动升程谐波。在舷外站（半径为86.5％），振动升程主要由弹性扭曲引起。在内侧站（半径为67.5％和77.5％），除了需要精确的扭曲之外，还需要精确的尾迹模型。准确捕获峰峰值音高链接负载和低谐波波形。即使在测量到的空载情况下，高次谐波扭转负载的差异仍未解决。预测的襟翼弯曲力矩在整个转子方位角上显示出约10度的相移。此错误源于1、2和3 / rev提升。 1 /转升程不受CFD / CSD耦合的影响。 2和3 / rev提升明显改善，但是不能完全解决2和3 / rev弯矩误差。

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