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首页> 外文期刊>Journal of the American Helicopter Society >Performance and Loads of a Reduced-Scale Coaxial Counterrotating Rotor
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Performance and Loads of a Reduced-Scale Coaxial Counterrotating Rotor

机译：缩小比例的同轴反向转子的性能和负载

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摘要

The results of hover and wind tunnel tests of a reduced-scale, closely spaced, rigid, coaxial counterrotating rotor system are presented, along with results from a comprehensive analysis. The system features two-bladed upper and lower rotors, 2.03 m in diameter, with uniform section, untwisted rotor blades. Measurements include upper and lower rotor steady and vibratory hub loads, as well as control angles and control loads. Blade tip clearance was measured using an optical sensor. The rotor system was tested in hover and at advance ratios between 0.21 and 0.53, at collective pitches ranging from 2 degrees to 10 degrees achieving blade loadings in excess of 0.10. At each forward flight operating condition, sweeps of lift offset up to 20% were performed, while selected test conditions were repeated at different rotor speeds and interrotor index angles. Hover tests showed that aerodynamic interaction between upper and lower rotors decreased individual rotor performance compared to isolated rotors and induced a four-per-revolution vibratory load corresponding to the blade passage frequency. In forward flight, the rotor effective lift-to-drag ratio was found to increase with increasing advance ratio and lift offset, resulting in a 30% improvement at 20% lift offset and 0.5 advance ratio. The lower coaxial rotor was found to operate at higher lift-to-drag ratio than the upper rotor, in contrast to the behavior in hover. Lift offset resulted in a decrease in blade tip clearance with a corresponding increase in rotor side force. Vibratory loads increased with advance ratio, with the largest loads in the two-and four-per-revolution harmonics. Lift offset, in conjunction with interrotor index angle, is shown to modify vibratory forces and moments transmitted to the fixed frame, increasing some force components while decreasing others.
机译：给出了缩小规模的，紧密分布的，刚性的，同轴反向旋转转子系统的悬停和风洞测试的结果，以及综合分析的结果。该系统具有直径为2.03 m的两叶上，下转子，截面均匀，转子叶片未扭曲。测量包括上，下转子的稳定和振动轮毂负载，以及控制角度和控制负载。刀片尖端间隙是使用光学传感器测量的。转子系统经过悬停测试，前进比在0.21到0.53之间，集体螺距在2度到10度之间，可实现超过0.10的叶片载荷。在每种前向飞行操作条件下，都执行了高达20％的升程偏移扫描，同时在不同的转子速度和转子间转角下重复了选定的测试条件。悬停测试表明，与隔离式转子相比，上，下转子之间的空气动力相互作用降低了单个转子的性能，并产生了与叶片通过频率相对应的每转四次的振动负载。在前向飞行中，发现转子的有效升阻比随提前比和升程偏移的增加而增加，从而在20％升程偏移和0.5提前比的情况下提高了30％。与悬停时的行为相反，发现下同轴转子比上转子具有更高的升阻比。升程偏移导致叶尖间隙减小，而转子侧向力相应增加。振动载荷随提前传动比的增加而增加，最大的载荷在每二次和每四次谐波中。升力偏移与转子间分度角一起显示，可以修改振动力和传递到固定框架的力矩，从而增加一些力分量，同时减小其他力分量。

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