The Identification Of Rotating Sources By Phased Array Measurements

Rotating machinery,for example the impeller machinery,produces the serious problem of the noise pollution when it provides the power for the industrial production.It is urgent to reduce this noise generated by the rotating machinery,and the most fundamental means of reducing the noise is to control the sound source.The identification of sound sources based on the microphone array can provide the important guidance for the active and passive control of sound sources.The existing identification methods of sound sources are usually restricted to the static condition.However,these methods are ineffective for identifying the rotating source due to the distinct Doppler effect.Therefore,this dissertation focuses on studying the identification method of the rotating source based on the microphone array.The detailed researches are shown in the following:In chapter one,the background and significance of rotating sound source identification is described first,and then by discussing the research status of rotating sound source identification technology and analyzing the existing problems,the main research contents of this dissertation are determined.In chapter two,in order to solve the problem of the low calculation efficiency in the existing identification methods of the rotating monopole source,an identification method of the rotating monopole source based on DAMAS2 is proposed.In this method,the Doppler effect caused by the rotating monopoles source is first analyzed,and its influence on the result of the sound source identification is also studied.Then,the rotating frame technology is applied in the DAMAS2 deconvolution algorithm to remove the influence of the Doppler effect and identify the rotating source,which can improve the resolution and computational efficiency.Finally,the effectiveness of proposed method is verified by numerical simulation and experimental analysis.In chapter three,in order to solve the problem of the rotating dipole source often encountered in practical engineering,an identification method of the rotating dipole source is proposed.Since the circumferential and axial dipole sources are the major sources in the actual rotating machines,two kinds of dipole Green functions are firstly deduced based on the spherical harmonic expansion.And the selections of the modal truncation numbers of the two kinds Green functions are analyzed.Then,the rotating frame technology is used to remove the Doppler effect.The results of removing the Doppler effect are applied in the Beamforming method and inversion technology to identify the high-frequency and low-frequency rotating source,respectively.Finally,the proposed method is validated by the numerical simulation and by the experiment of the unmanned aerial vehicle rotating blades.In chapter four,in order to solve the problem of the high measurement expense in duct,an identification method of the rotating source in duct based on the Orthogonal Matching Pursuit(OMP)algorithm is proposed.In this method,the sound field characteristics of the rotating source in duct are first analyzed.Then,the rotating frame technique is used to remove the Doppler effect caused by the rotating source in duct.The results of removing the Doppler effect are used as the inputs of the OMP algorithm to achieve the identification of the rotating source in duct.The proposed method can use the less microphones to obtain the high-resolution identification results,which reduces the measurement expense and improves the measurement efficiency.Finally,numerical simulation is used to evidence the feasibility of the proposed method.In chapter five,the whole research work of the dissertation is summarized,and several topics needing further study are given.