The Research And Realization Of Acoustic Measurement System In Aeroacoustic Wind Tunnel

Aeroacoustic wind tunnel is the important platform of aeroacoustic study. In order to ensure our country’s the first large-scale low-speed aeroacoustic wind tunnel to obtain the ability to carry out the aeroacoustic test as soon as possible, our research builded an acoustic measurement system composing of phased microphone array, multi-channels parallel data acquisition equipment and measurement processing software.In the thesis, we introduced the background and origin of our research, and discussed the current research status of aeroacoustic test both at home and abroad. Meanwhile, we also studied the present status of aeroacoustic measurement instrument, which pointing out the direction for our research. Then, basing on the beamforming, we deduced the key technology index of evaluating the array’s performance, and analyzed how the measuring condition affected array’s resolution and dynamic range. According to the demand of the actual measurement, we analyzed the performance characteristics of variety array’s structure. Basing on the theoretical analysis, we successfully designed and processed a large multi-arm spiral phased array composing of 140 microphones. Then, basing on the test object and technical indicators, we analyzed the special requirements to microphone and data acquisition equipment in aeroacoustic test. And in combination with cutting-edge technology of the measurement field, we built a parallel data acquisition system with 256 channels. Then, the design of spectrum subtraction which can deduct background noise and help us get the aerodynamic noise energy within a specified bandwidth. Then, we analyzed the influence of the jet shear layer for the identification of aerodynamic noise source, and the corresponding correction methods were given. Then, we introduced the design of measurement processing software in detail. Using the plug and play technology, the automatic identification of acoustic sensor information has been realized by software; Through the system calibration function, to ensure the accuracy and reliability of the test results; Through the on-line function based on TCP technology, realize the automatic operation of the system; Designed a perfect system running state monitoring and fault diagnosis process, to improve the reliability and security of the system; Through the data storage solution based on TDMS technology, the standardization storage and rapid query of massive data has been realized; Developed a powerful software for data process, has realized the rapid processing, display and storage of experimental data.Finally, in order to investigate the practical application and operation status of the acoustic measurement system, we completed a confirmatory aeroacoustic test in 5.5m×4m aeroacoustic wind tunnel, and satisfactory results were obtained.