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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。
Rotor wake and stator blade interference is one of the main noise sources for generating fan discrete noise. The ring cascade geometry has important influence on the solution of sound source and the propagation of sound in the pipeline. Therefore, the discussion of the effect of the blade swept combination design on the passive control of fan noise needs to emphasize the influence of three-dimensional effect. In this paper, a three-dimensional lifting surface theory is used to establish aeroacoustic model which can consider the effect of blade swept combination. Compared with the numerical calculation method, the theory of three-dimensional lift surface does not have the influence of dispersion and dissipation, the solution is fast and efficient, and more conducive to the optimization design of the initial stage, as well as to verify the numerical calculation model. Through the comparison with the existing results, the influence mechanism of blade swept and circumferential tilt on fan discrete noise is further elaborated. However, the calculation results of the calculation example of the combination of swept and swept show that under certain conditions, the selection of a suitable blade swept shape can obtain a good noise reduction effect. Due to the influence of the axial wave number, there is a certain difference in the changing tendency of the pre-transmitted sound field and the post-transmitted sound field.