This paper proposes a synchronous measurement method for broadband acoustic modal identification based on a combined microphone array, which can overcome the acoustic modal aliasing problem caused by a limited number of microphones. In the proposed method, the cross-correlation combination of axial and circumferential arrays is performed by utilizing the relevant characteristics of turbulent noise modes, thereby realizing modal identification of turbulent noise in a wide range with a small number of acoustic measurement points. For fast iteration, the modal cross terms are optimized by leveraging the relevant characteristics of turbulent noise modes. This method can effectively distinguish the distribution information of forward and backward propagating acoustic modes. The accuracy of the identified acoustic modes is verified through numerical simulations, and the method is experimentally validated using experimental results from an axial flow compressor. The results show that this method can effectively suppress the aliasing problem. Compared with the traditional rotating axial array method, it has higher testing efficiency in circumferential and radial modal identification, requires fewer sound pressure measurement points, and is more suitable for rapid evaluation of noise reduction designs.

Kunbo Xu, male, associate professor and master's supervisor, member of the Chinese Aeronautical Society and member of the Chinese Vibration Engineering Society. Research directions include modal identification and noise reduction technology for turbomachinery, as well as teaching and research in digital signal processing and big data algorithms. 

As the project leader, presides over multiple scientific research projects, including the National Natural Science Foundation, the Ministry of Education Humanities and Social Sciences Foundation, the Jiangsu Provincial Natural Science Foundation, planning projects of the China Higher Education Society, and open projects of the Key Laboratory of Aerodynamic Noise Control. He has published more than 20 papers in authoritative academic journals at home and abroad.