普通室内机翼尾缘噪声降噪的实验研究

Experimental Investigation of Airfoil Trailing-Edge Noise Reduction in a Normal Indoor Test Bed

关键词:  麦克风阵列  机翼  尾缘噪声  混响  锯齿

Key words:  Microphone array  Airfoil  Trailing-edge noise  Reverberation  Serrations

摘要:

为了研究锯齿形尾缘对SD2030低雷诺数翼型尾缘噪声的影响，在普通室内，采用由31路麦克风组成的线性阵列对SD2030吹风试验进行了声学测量。实验过程中，基于机翼弦长的雷诺数范围为2.1×105 ～ 3.2×105。在考虑混响、驻波和壁面反射影响的基础上，设计了一长为1.72m的非等间距线性阵列。当频率大于1kHz时，墙壁反射对测量结果的影响在0.5dB以内，驻波的影响也可以忽略。采用时域波束成形算法对声学信号进行处理之后，成功识别出了风洞噪声源、机翼前缘噪声源和尾缘噪声源。比较直尾缘机翼和锯齿形尾缘机翼的声源分布图发现，在1k～10kHz的频率范围内，采用锯齿形尾缘设计能够降低尾缘噪声声压级最大约5dB。

Abstract:

A phased array with 31 microphones is used to investigate the noise reduction effects of serrated trailing edge (TE) on SD2030 low Reynolds number airfoils in a normal indoor test bed. During the acoustic measurement，the Reynolds number based on airfoil chord ranges from 2.1×105 to 3.2×105. After combining array design with the indoor acoustic environments such as reverberation，standing waves and reflection waves from hard walls，an unequal spacing linear microphone array with length of 1.72m is built. The hard wall reflection effects on test signals are less than 0.5dB in frequency range above 1kHz and the influences of standing waves can be neglected，too. Conventional beam-forming in time domain is applied to process the microphone signals，as a result，noise sources including wind tunnel noise source，airfoil leading-edge and trailing-edge noise source have been identified successfully. According to comparison between the noise source distribution maps of straight trailing-edge case and serrated trailing-edge case，the sound pressure level of trailing-edge noise can be approximately reduced by 5 dB at most in frequency ranges from 1kHz to 10kHz.