中文摘要：

转子尾迹与静子叶片干涉是产生风扇离散噪声的主要噪声源之一。环形叶栅几何对于声源项的求解以及管道内的声传播都有重要影响,因此在讨论叶片弯掠组合设计对于风扇噪声的被动控制作用时需要重点强调三维效应的影响。本文利用三维升力面理论,建立了可以考虑叶片弯掠组合影响的气动声学模型。相比数值计算方法,三维升力面理论不存在频散耗散影响,求解快速高效,更加有利于初始阶段的优化设计,以及为数值计算模型提供验证。通过与已有结果的对比,进一步阐述了叶片后掠和周向倾斜对于风扇离散噪声的影响机制。而弯掠组合设计算例的计算结果表明,在某些条件下,选取合适的叶片弯掠造型能够获得很好的降噪效果。由于轴向传播波数的影响,前传声场和后传声场对于弯掠组合的变化趋势存在一定的差异性。

英文摘要：

Rotor wake/stator interaction is one of the primary sound sources of fan tonal noise.As the annular-cascade geometry has important impact on the solution for sound sources and sound propagation in the duct,the three-dimensional effect should be emphasized in the discussion of passive control of fan noise by vane sweep and lean.In this paper,the three-dimensional lifting surface method is employed as the vane response function to calculate the unsteady surface pressure and the radiated sound field.In comparison with the numerical solutions,there is no dispersion or dissipation in this method.With high efficiency,this method is more suitable for the early stage of the design,and can provide the validation for numerical solutions.The mechanism of fan noise reduction by vane sweep and lean is further discussed by a comparison with existing results.The calculation result of the swept-and-leaned vanes shows that,in some condition,the suitable combination of swept and leaned angles can gain very good control performance for fan tonal noise reduction.Because of the difference in axial wave-numbers,the sound power changing trends with swept and leaned vanes would be different for upstream and downstream.