Piezoelectric Actuator Acoustic Liner And Muffler Performance Research

Noise pollution widely exists in various fields of social life, industrial and agricultural production. Noise Suppression or elimination by different means or eliminate is always a hot issue both in engineering and academic domain. Lining technology on the aircraft engine, air pipe and other fluid machinery has been broadly used in the noise suppression. The adaptive acoustic liner has important theoretical significance and engineering practical value to control the broadband noise and will promote the research and development level of mechanic. Based on the study of vortex sound theory and the basis of piezoelectric synthetic jet, a prototype of acoustic liner consists of piezoelectric actuators is proposed in this thesis. The acoustic liner can suppress the noise in the fluid machinery, such as aviation engine compartment, air pipe and so on.According to the working principle of piezoelectric actuator line, piezoelectric actua tor unit was designed and analyzed. To analyze and calculate the mechanical properties of liner, the finite element model of the piezoelectric patch was established. Then, the modal analysis was carried out to calculated the natural frequency of the piezoe lectric element. By harmonic response analysis, when the driving frequency is close to the natural frequency of the piezoelectric patches, the resonance phenomenon was obtained, which will affect the lifetime of such liner.According to the basic theory of vortex muffler, the jet produced by piezoelectric acoustic liner was analyzed. The finite element models of the piezoelectric patch and the flow field outside acoustic liner were established. Multi-domain coupling analysis including electric field, flow field and structure field was conducted. The simulation results indicate that the jet velocity from the piezoelectric actuator acoustic liner increases with the enhance of the amplitude and the frequency of excitation voltage; the jet velocity of the piezoelectric actuator acoustic liner decreases with the increase of the bore diameter of acoustic liner units; and will reach the maximum value, 96.4 m/s, when the height of spray hole is 1mm. The jet velocity tend to stable when the height of the cavity in the range of 1 mm to 2 mm, and it decreases distinctly when the height of the cavity greater than 2 mm or less than 1 mm.The Data Acquisition program and the Auto Control program were developed by LABVIEW software. The measurement system of acoustic absorptivity was invented and used to conduct experiments. According to the evaluation of the acoustic about acoustic liner, some experimental programs were designed. Through the test of the jet velocity of the piezoelectric actuator acoustic liner, the relationship between the jet velocity and the excitation power was further studied. The test of the absorption coefficiency confirm that this acoustic liner could absorb sounds. Within the incident frequency range from 700 Hz to 900 Hz,the absorption coefficiency enhances significantly,the maximum increasement is 0.5. The Transmission loss measurements withdraw the conclusion as follows, within the incident frequency range from 700 Hz to 800 Hz,the Transmission loss of the pipeline with acoustic liner increases significantly,its maximum increasement is 0.8. Both of the results indicate that this proposed acoustic liner could enhance the Muffler performance. Compared with the traditional liner, the piezoelectric acoustic liner has a better anechoic performance and absorption performance.