| In the aerospace industry,a complex structure,a cavity structure,is formed.When the airflow flows through the cavity at high speed,complex turbulence is formed..On the one hand,the cavity turbulent flow will form a complex flow structure,on the other hand,it will form a complex and strong aerodynamic noise in the cavity.If the aircraft thickness design can not meet the requirements,the disintegration of the aircraft will result in irreparable losses.On the other hand,if the aircraft thickness design margin is too large,it will increase the weight of the aircraft and reduce the flexibility of the aircraft.Therefore,it is of great significance to study the characteristics of the cavity.In this paper,the pulsating pressure sensor array distributed in the cavity is used to study the characteristics of the cavity pulsating pressure.Firstly,under two Mach numbers,the pulsating signals collected by the pulsating pressure sensors at different positions in the distributed array are analyzed in different domains such as time domain,frequency domain,and time-frequency domain to determine the main components of the pulsating pressure signal.And determine its approximate frequency range.Secondly,the mathematical model of the pulsating pressure signal is determined.The minimum mean square error logarithmic spectral amplitude estimation(MMSE-LSA)is used to de-noise the fluctuating pressure signal generated by background noise.A set of arithmetic based on similar function frequency-domain peak statistic is deduced for the fluctuating pressure signal produced by the vibration of support rod.Firstly,the pulsating pressure signals collected by the distributed array are arranged according to the time-series relationship,and then the similarity calculation is carried out in turn.The total sampling points are subtracted from a similar curve.Then,the frequency components corresponding to several maximal peaks in the frequency domain are extracted after Fourier transform of all the similar curves.Finally,the frequency components extracted are counted to obtain the vibration of the support rod.Frequency component of pulsating pressure signal.The validity of the peak statistic algorithm in similar function frequency domain is verified by simulation experiments,and the frequency component extraction of the fluctuating pressure signal generated by the support rod vibration is realized.Then,Based on the variation of sound pressure level with time,a multi-domain analysis method based on energy temporal similarity in frequency domain of distributed array is deduced.Firstly,the optimal expression of the pulsating pressure test data time/frequency sound pressure level is obtained,and the timing is aligned and combined.The spatial position of the distribution array forms the spatial distribution map of the sound pressure level,and then the time series similarity analysis is performed on the optimal expression of the time/frequency sound pressure level to obtain the time-varying law of the sound pressure level in the cavity.The effectiveness of the multi-domain analysis method is verified by simulation experiments,and the sound pressure level evolution of the wind tunnel experiment under two Ma numbers is obtained respectively,and the law is demonstrated through visualization to reveal different positions of the cavity.The time-varying law of sound pressure level.Finally,the content of this study is summarized,and the shortcomings and the following research priorities are pointed out,which indicates the research direction for the follow-up research. |
