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首页> 外文期刊>Journal of the American Helicopter Society >A Comparison of Coaxial and Conventional Rotor Performance
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A Comparison of Coaxial and Conventional Rotor Performance

机译：同轴和常规转子性能的比较

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The performance of a coaxial rotor in hover, in steady forward flight, and in level, coordinated turns is contrasted with that of an equivalent, conventional rotor with the same overall solidity, number of blades, and blade aerodynamic properties. Brown's vorticity transport model is used to calculate the profile, induced, and parasite contributions to the overall power consumed by the two systems, and the highly resolved representation of the rotor wake that is produced by the model is used to relate the observed differences in the performance of the two systems to the structures of their respective wakes. In all flight conditions, all else being equal, the coaxial system requires less induced power than the conventional system. In hover, the conventional rotor consumes increasingly more induced power than the coaxial rotor as thrust is increased. In forward flight, the relative advantage of the coaxial configuration is particularly evident at pretransitional advance ratios. In turning flight, the benefits of the coaxial rotor are seen at all load factors. The beneficial properties of the coaxial rotor in forward flight and maneuver, as far as induced power is concerned, are a subtle effect of rotor-wake interaction and result principally from differences between the two types of rotor in the character and strength of the localized interaction between the developing supervortices and the highly loaded blade-tips at the lateral extremities of the rotor. In hover, the increased axial convection rate of the tip vortices appears to result in a favorable redistribution of the loading slightly inboard of the tip of the upper rotor of the coaxial system.
机译：同轴旋翼在盘旋，稳定向前飞行和水平，协调转弯方面的性能与具有相同整体坚固性，叶片数量和叶片空气动力学特性的同等传统旋翼的性能形成对比。布朗的涡度输运模型用于计算两个系统消耗的总功率的分布，感应和寄生贡献，并且模型产生的转子尾流的高度分辨表示用于关联观测到的差异。两个系统的性能与其各自的尾流的结构有关。在所有其他条件相同的所有飞行条件下，同轴系统所需的感应功率比常规系统要少。在悬停时，随着推力的增加，常规转子比同轴转子消耗的感应功率越来越大。在向前飞行中，同轴结构的相对优势在过渡前的前进传动比时特别明显。在转弯飞行中，在所有负载系数下都可以看到同轴转子的优点。就感应功率而言，同轴转子在前向飞行和操纵中的有益特性是旋翼-尾流相互作用的微妙影响，主要是由于两种类型的旋翼之间在局部相互作用的特性和强度上的差异而产生的在正在发展的超涡流和转子侧端的高负荷叶尖之间。在悬停时，尖端涡流的轴向对流速率的增加似乎导致载荷的有利重新分配，该载荷稍稍向同轴系统的上转子尖端的内侧靠内。

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