构件在超音速气流环境下的辐射声场特性分析

Analysis of Radiated Acoustic Characteristics of Structures in the Supersonic Airflow

在超音速环境中,构件所产生的辐射噪声往往容易被高强背景噪声所淹没,难以被提取出来,给结构的降噪设计带来困难。因此,提出了一种基于集合经验模态分解(EEMD)的构件辐射声场特性分析方法。首先,通过传声器阵列采集气流背景噪声;放入构件后,再次采集新的辐射噪声信号。然后,采用EEMD对采集的信号进行多尺度分解,根据各个尺度信号的相关性大小,提取出气流环境中有无构件情况下的差异性特征成分。最后,通过波束形成方法对提取出的信号成分进行声场重构,确定构件对气流的主要扰动位置和辐射噪声强度。在5Mach气流环境中,对平板件、尖劈件分别进行了实验分析,结果表明,新方法能够有效提取出放入构件后辐射噪声场的变化成分,并重构出构件扰动辐射噪声场的主要噪声源位置和辐射噪声的大小。

The high-intensity background noise in the supersonic environment makes it difficult to extract the radiated noise generated by the structure placed in the airflow, which brings difficulties to the noise reduction design of the structure. Therefore, a method for analyzing the radiated noise field characteristics of structure is proposed based on the ensemble empirical mode decomposition(EEMD). First, the airflow background noise is collected through the microphone array and a new radiated noise signal is acquired again when the structure is placed in the airflow. Then,EEMD is used to perform decomposition on the acquired signals, and according to the correlation of the signals of each scale, the differential characteristic in the presence and absence of structure in the airflow are extracted. Finally, the acoustic field is reconstructed by using signals extracted through beamforming to determine the main disturbance position of the structure to the airflow. Experiments were carried out on the flat and the wedge specimen in the 5-Mach airflow. The results show that the new method can effectively extract the variation component of the radiated noise field after the structure is placed in the airflow and reconstruct the main noise source of the radiated noise disturbed by structure and that of the intensity.