Study On Identification And Location Of Moving Sound Sources

With the development of modern advanced aviation aircraft,the aerodynamic noise level as an important index to measure the performance of the aircraft,which have drawn more and more attention in the world.The sound sources location technique using microphone array as an important means for the experimental study of aerodynamic noise,which can provide a reliable basis for the theoretical analysis and numerical simulation,so it has been more studied.However,most traditional sound sources location technique using microphone array which only can locate stationary objects and simple uniform linear moving objects,there are fewer research about the aerodynamic noise location of moving objects.For example the aerodynamic noise of propeller aircraft and helicopter,it's difficult to modify the Doppler Effect of the sound signal by means of mathematics,which leads to the traditional sound location technique is invalid.So it's necessary to study the methods of moving sound sources location in the wind tunnel.Through the study in this thesis,we can get a method of moving sound sources location and an array optimization design methods for moving sound sources,which successfully used to locate the aerodynamic noise of rotating blades.Specific contents of this thesis are as follows:The first chapter introduces the research background of this thesis,and introduces the research progress of moving sound sources location technique at home and abroad.In the second chapter,the principle of the beamforming algorithm using microphone array is introduced,then the mathematical relationship between the sidelobes position of the beamforming and the array radius,the wavelength of the sound sources and the scanning distance is obtained by analyzing the ring microphone array.According to the mathematical relationship of the sidelobes position,the position and the number of the beamforming sidelobes can be accurately predicted.Through further analysis,we can get the lower limit of the number of the microphone,the optimal resolution and other results of the ring array.The dynamic range and resolution of the beamforming can be improved by combining some annular microphone arrays with specific size relationship,which can achieve the optimization of the microphone array.In the third chapter,the sound field of a moving monopole sound source in a uniform flow field is introduced,which called transfer function can establish the relationship between the sound source signal and the measured signal.On the other hand,according to the experimental characteristics of the open jet wind tunnel,the sound signal through the shear layer of the flow field is modified.Then,by combining the beamforming algorithm and transfer function,the identification and location of moving sound source is realized.Simulation analysis is carried out for the recognition error caused by noise signal interference and measurement error which may be encountered in the process of moving sound source identification.The “DAMAS” algorithm is introduced to the identification of moving sound source,and the feasibility of the “DAMAS” algorithm is realized by simulation.At last,according to the contrast of moving sound source and static sound source,the characteristics of moving sound source identification is obtained,which can be using to optimize the microphone array for the moving sound source.The fourth chapter introduces the experimental study to verify the accuracy of the moving sound sources identification procedures,and the use of moving sound sources identification procedures rotor aerodynamic noise were studied to determine the sound sources.In the fourth chapter,the accuracy of the moving sound sources identification procedure is verified by experimental study,and the rotor aerodynamic noise test is carried out,and the sound source is determined by using the program of sound source identification.The fifth chapter summarizes the work of this paper,and points out the shortcomings of this study and the direction of the future research.