This study conducts an aeromechanics analysis of a modern lift-offset coaxial rotor in high-speed flight. A lift-offset coaxial rotor of the Sikorsky X2 technology demonstrator (X2TD) is considered for the present study. For the analyses of rotor performance, blade airloads, and hub vibratory loads, a rotorcraft comprehensive analysis code, CAMRAD II, is used. For the rotor performance analysis at a flight speed of up to 250 knots, which is the maximum level flight speed of X2TD in flight test, the present prediction of rotor power is compared well with the flight test data. For the blade section airload analysis at 250 knots, the impulses of the section lift forces are observed because of the aerodynamic interactions between the upper and lower rotors. The 4/rev hub vibratory loads are predicted, and its variation trend is moderately compared with the previous analysis results. Furthermore, the rotor vibration index increases significantly in high-speed flight with an increase in the flight speed, and this is well correlated with the previous rotorcraft comprehensive analysis result. This study shows that the present modeling and analysis techniques are appropriate to analyze the aeromechanics, including the performance, blade airloads, and hub vibratory loads of a modern lift-offset rotor in high-speed flight.

中文翻译：

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高速前进飞行中现代升力偏置同轴旋翼的气动力学分析

本研究对高速飞行中的现代升力偏置同轴转子进行了空气力学分析。本研究考虑使用西科斯基 X2 技术演示器 (X2TD) 的升降偏置同轴转子。对于旋翼性能、叶片空气载荷和轮毂振动载荷的分析，使用了旋翼飞机综合分析代码 CAMRAD II。对于X2TD在飞行试验中最高水平飞行速度250节的旋翼性能分析，将目前的旋翼功率预测与试飞数据进行了很好的对比。对于 250 节的叶片截面空气载荷分析，由于上下转子之间的空气动力学相互作用，可以观察到截面升力的脉冲。预测 4/rev 轮毂振动载荷，其变化趋势与之前的分析结果相比较为温和。此外，高速飞行中旋翼振动指数随着飞行速度的增加而显着增加，这与之前的旋翼机综合分析结果有很好的相关性。这项研究表明，目前的建模和分析技术适用于分析高速飞行中现代升力偏置旋翼的性能、叶片空气载荷和轮毂振动载荷等航空力学。