Blade-Geometry Considerations in Analytical Gust-Airfoil Interaction Noise Models
Blade-Geometry Considerations in Analytical Gust-Airfoil Interaction Noise Models
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DOI：
10.2514/6.2010-3799
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发表时间：
2010-06
期刊：
影响因子：
--
通讯作者：
M. Roger;A. Carazo
中科院分区：
文献类型：
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作者：
M. Roger;A. Carazo
目前的工作致力于扩展经典的分析阵风-翼型相互作用噪声模型，致力于预测扭曲流中旋转叶片的音调噪声。更具体地说，它的目的是在螺旋桨设计的早期阶段为反向旋转开式转子提供一致的预测工具。事实上，安装在飞机后机身等处的 CROR 预计会由于叶片尾流相互作用以及与桅杆尾流的相互作用而辐射声音，并且该噪声的音调部分被认为是主要的。在采用条带理论的经典公式中，假设叶片片段是包含在无限跨度板中的矩形补片，则导出叶片片段的局部响应。在本文中，提出了更真实形状的新表达式，即后掠叶片段的平行四边形、考虑沿翼展的弦长变化的多边形以及矩形叶片尖端的特殊情况。对于由确定性事件扰动引起的非定常升力，获得了闭式解，在需要时引入近似值，并大量使用史瓦西技术。接下来根据声学类比计算远场声音。通过与矩形段的基线情况进行比较，讨论了实际几何参数对声辐射的影响。
The present work addresses extensions of a classical, analytical gust-airfoil interaction noise model, dedicated to the prediction of the tonal noise of rotating blades in a distorted flow. More specifically it is aimed at providing consistent prediction tools for CounterRotating Open Rotors at the early stage of propeller design. Indeed CRORs, installed for instance at the rear fuselage of an aircraft, are expected to radiate sound because of the blade-wake interactions and of the interaction with the wake of the mast, and the tonal part of that noise is recognized as dominant. In classical formulations resorting to a strip theory, the local response of a blade segment is derived assuming that the segment is a rectangular patch included in a plate of infinite span. In the paper, new expressions are proposed for more realistic shapes, namely a parallelogram for segments of swept blades, polygons accounting for chord length variations along the span, and the special case of a rectangular blade tip. Closed-form solutions are obtained for the unsteady lift induced by deterministic incident disturbances, introducing approximations when needed, and making an intensive use of Schwarzschild’s technique. Next the far-field sound is calculated according to the acoustic analogy. The effects of the realistic geometrical parameters on the sound radiation are discussed by comparing to the baseline-case of a rectangular segment.