Acoustic signals contain rich discharge information.In this study,the acoustic signal characteristics of transient glow,spark,and glow discharges generated through DC pin–pin discharge were investigated.The signals w...Acoustic signals contain rich discharge information.In this study,the acoustic signal characteristics of transient glow,spark,and glow discharges generated through DC pin–pin discharge were investigated.The signals were analyzed in the time,frequency,and time–frequency domains,and the correlation between the electric and the acoustic signal was studied statistically.The results show that glow discharge does not produce measurable sound signals.For the other modes,with a decrease in the discharge gap,the amplitude of the acoustic signal increases sharply with mode transformation,the short-time average energy becomes higher,and the frequency components are more abundant.Meanwhile,the current pulse and sound pressure pulse have a one-to-one relationship in the transient glow and spark regimes,and they are positively correlated in amplitude.A brief theoretical analysis of the mechanism of plasma sound and the trends of signals in different modes is presented.Essentially,the change in the discharge energy is closely related to the sound generation of the plasma.展开更多
Based on the problem that the generating method of random array structure is inefficient, a method is proposed to generate the random target arrays by using coaxial circu- lar array in the polar coordinates in the pre...Based on the problem that the generating method of random array structure is inefficient, a method is proposed to generate the random target arrays by using coaxial circu- lar array in the polar coordinates in the premise that the array angular resolution of source identification is guaranteed. According to the principle of moving sound source identification, this work deduces the basic non-equidistance coaxial circular rings＇ radius, and generates target random arrays which were suitable for moving sound source identification through array partitioning, condition filtering in the polar coordinates and simulation evaluation. Finally, numerical simulation and moving car sound source identification test have been done. The analytical results show that using this method to generate random array is effective. Compared with the traditional regular arrays, the target random array has more accurate moving sound source identification performance.展开更多
The directionality of the sound generated by lase r-induced liquid breakdown in water is investigated both theoretically and experimentally. The theoretical analysis is based on the following model. A series of small ...The directionality of the sound generated by lase r-induced liquid breakdown in water is investigated both theoretically and experimentally. The theoretical analysis is based on the following model. A series of small spherical cavities including plasma are homogeneously distributed on a short straight line segment and every such cavity may be considered as a point source radiating acoustic impulse. Theoretical expressions of the relations between the amplitude and width of acoustic impulse and the receiving direction are given. Experimental results are in agreement with theoretical predictions.展开更多
When gas flows through corrugated pipes,pressure waves interacting with vortex shedding can produce distinct tonal noise and structural vibration.Based on established observations,a model is proposed which couples an ...When gas flows through corrugated pipes,pressure waves interacting with vortex shedding can produce distinct tonal noise and structural vibration.Based on established observations,a model is proposed which couples an acoustic pipe and selfexcited oscillations with vortex shedding over the corrugation cavities.In the model,the acoustic response of the corrugated pipe is simulated by connecting the lossless medium moving with a constant velocity with a source based on a discrete distribution of van der Pol oscillators arranged along the pipe.Our time accurate solutions exhibit dynamic behavior consistent with that experimentally observed,including the lock-in frequency of vortex shedding,standing waves and the onset fluid velocity capable of generating the lock-in.展开更多
基金supported by National Natural Science Foundation of China(No.52177145)。
文摘Acoustic signals contain rich discharge information.In this study,the acoustic signal characteristics of transient glow,spark,and glow discharges generated through DC pin–pin discharge were investigated.The signals were analyzed in the time,frequency,and time–frequency domains,and the correlation between the electric and the acoustic signal was studied statistically.The results show that glow discharge does not produce measurable sound signals.For the other modes,with a decrease in the discharge gap,the amplitude of the acoustic signal increases sharply with mode transformation,the short-time average energy becomes higher,and the frequency components are more abundant.Meanwhile,the current pulse and sound pressure pulse have a one-to-one relationship in the transient glow and spark regimes,and they are positively correlated in amplitude.A brief theoretical analysis of the mechanism of plasma sound and the trends of signals in different modes is presented.Essentially,the change in the discharge energy is closely related to the sound generation of the plasma.
基金supported by the National Natural Science Foundation of China(61271387)the Natural Science Foundation of Shandong Province(ZR2012FZ001)
文摘Based on the problem that the generating method of random array structure is inefficient, a method is proposed to generate the random target arrays by using coaxial circu- lar array in the polar coordinates in the premise that the array angular resolution of source identification is guaranteed. According to the principle of moving sound source identification, this work deduces the basic non-equidistance coaxial circular rings＇ radius, and generates target random arrays which were suitable for moving sound source identification through array partitioning, condition filtering in the polar coordinates and simulation evaluation. Finally, numerical simulation and moving car sound source identification test have been done. The analytical results show that using this method to generate random array is effective. Compared with the traditional regular arrays, the target random array has more accurate moving sound source identification performance.
基金The project is supported by National Natural Science Foundation of China.
文摘The directionality of the sound generated by lase r-induced liquid breakdown in water is investigated both theoretically and experimentally. The theoretical analysis is based on the following model. A series of small spherical cavities including plasma are homogeneously distributed on a short straight line segment and every such cavity may be considered as a point source radiating acoustic impulse. Theoretical expressions of the relations between the amplitude and width of acoustic impulse and the receiving direction are given. Experimental results are in agreement with theoretical predictions.
文摘When gas flows through corrugated pipes,pressure waves interacting with vortex shedding can produce distinct tonal noise and structural vibration.Based on established observations,a model is proposed which couples an acoustic pipe and selfexcited oscillations with vortex shedding over the corrugation cavities.In the model,the acoustic response of the corrugated pipe is simulated by connecting the lossless medium moving with a constant velocity with a source based on a discrete distribution of van der Pol oscillators arranged along the pipe.Our time accurate solutions exhibit dynamic behavior consistent with that experimentally observed,including the lock-in frequency of vortex shedding,standing waves and the onset fluid velocity capable of generating the lock-in.
