大型客机前起落架气动噪声源三维阵列识别技术研究

An investigation on landing gear noise by three-dimensional microphone array

起落架噪声作为现代大型飞机机体噪声在起降阶段的主要贡献成分,其噪声机理较为复杂,涉及到钝体湍流涡脱落噪声、腔体部件空腔噪声以及起落架舱腔体与支柱柱体之间的非线性耦合噪声。由于起落架中存在复杂的三维流场以及声波的反射和绕射会产生噪声,而二维麦克风阵列在垂向的分辨率较差,无法获得声源完整且准确的三维空间分布信息,因此采用三维麦克风阵列技术对起落架噪声进行研究。使用3D Beamforming算法(波束成形算法)和3D CLEAN-SC算法(空间相干的洁净算法)结合同步测量和非同步测量的方式实现了对模拟信号和实际测量数据所得频谱中特定的离散声进行声源识别定位,并在北航D5低速风洞进行开口段气动噪声实验,以1/2缩比的LAGOON起落架为研究对象,在过顶和流向方向布置两组平面阵列,构成三维阵列进行同步和非同步的噪声测量,确定了起落架中主要噪声源的位置,对认知噪声机理提供了新的借鉴和思考。

Landing gear noise is the main contribution component of modern large aircraft body noise during takeoff and landing,and its mechanism is complex,including bluff body turbulent vortex shedding noise,cavity noise of cavity components and nonlinear coupling noise between landing gear cabin and strut column.Because of the complex three-dimensional flow field in the landing gear and the noise generated by the reflection and diffraction of acoustic waves,and the poor vertical resolution of two-dimensional microphone array,it is impossible to obtain the complete and accurate three-dimensional spatial distribution information of the sound sources.Therefore,the three-dimensional microphone array technology is used to study the landing gear noise.In this paper,3D Beamforming algorithm(Beamforming algorithm)and 3D CLEAN-SC algorithm(spatial coherent CLEAN algorithm)were used to identify and locate the specific discrete sound sources in the spectrum obtained from analog signals and actual measured data by combining synchronous and asynchronous measurement methods.The open-end aerodynamic noise experiment was carried out in the D5 low-speed wind tunnel of Beihang University.Taking LAGOON landing gear with 1/2 scale as the research object,two planar arrays were arranged in the overhead direction and the direction of flow to form a three-dimensional array for synchronous and asynchronous noise measurement,and the location of the main noise sources in the landing gear was determined,which provides a new reference and thinking for cognitive noise mechanism.