ARJ21客机降落阶段起落架噪声试验研究

Landing gear noise identification in the ARJ21 aircraft landing process

为了测量ARJ21客机的起落架噪声,在飞行现场分别采用改进的频域波束形成和解卷积算法对降落阶段的起落架噪声进行了测量。通过比较两种算法发现,解卷积算法比改进的频域波束形成算法具有更好的声源识别能力。为了提高传声器的利用率,设计了多臂螺旋阵,并且利用线性插值消除了多普勒效应。根据主起落架和前起落架的分布位置不同,将声源识别区域划分为两部分,在140—800Hz范围内对不同频段的1/3倍频程的起落架噪声进行了测量。结果发现:在250 Hz以上频段,主起落架为主要噪声源,且在中心频率500 Hz的1/3倍频程内为唯一强声源;前起落架在中心频率630 Hz的1/3倍频程内为主要噪声源。通过试验得到了主起落架和前起落架噪声在不同频段的分布特点,为起落架降噪设计提供了支持。

The acoustic flyover tests are performed for an ARJ21 aircraft with the objective to measure the landing gear noise. The algorithms of improved frequency domain Conventional Beamforming （CBF） and Deconvolution Approach for the Mapping of Acoustic Sources （DAMAS） are used. It is demonstrated that DAMAS has better capability of noise source identification. In order to improve the utilization of the microphones, a multi-arms spiral array is designed and applied to the measurement. The doppler effect is removed by using linear interpolation. According to the distribution of the main landing gear and nose landing gear, the identification area is divided into two parts and is analyzed from i40 Hz to 800 Hz on 1/3 octave band. It is shown that the main landing gear is the main noise source above 250 Hz. Especially, it is the only strong noise source in 1/3 octave band of 500 Hz centre frequency, whereas the nose landing gear is the main noise source in 1/3 octave band of 630 Hz centre frequency. By this test, the noise characteristics of the main landing gear and nose landing gear are investigated in different frequency range which is significant to landing gear noise control engineering.