The Research Of Tunable Piezoelectric Acoustic Liner And Its Control

Acoustic liner as an effective means of noise control,has the advantages of convenient installation,low price,high frequency sound absorption coefficient,and is widely used in aircraft engines,vehicle power cabin and architectural design and industrial equipment etc.But it is restricted by the traditional noise frequency acoustic liner material characteristic,structure,and its silencer frequency range is narrow,when the noise source is changed,the working frequency can't be adjusted,so the research of tunable acoustic liner has great theoretical significance and practical value.In this paper,based on the analysis of the working principle and the acoustic performance of the existing acoustic liner,a new type of adjustable frequency acoustic liner has been proposed.Firstly,the structure of the Helmholtz resonator with neck adjustment and cavity volume adjustment has been designed based on the inverse piezoelectric effect.The simulation results show that the cavity volume adjustable structure has the characteristics of large frequency offset range and good linearity.On the basis of optimizing the cavity volume adjustable structure,a double chamber cavity acoustic liner has been proposed,and the factors influencing the resonance frequency offset are analyzed theoretically.After analyzing various types of piezoelectric test optimization,experiment after parameter optimization of 50 mm piezoelectric substrate,i the copper plate diameter is 50 mm,the thickness is 0.1mm,the diameter of the piezoelectric ceramic is 30 mm,the thickness is 0.12 mm,when the voltage is 400 V,the displacement is 0.5mm.Secondly,by using the LabVIEW software,the transmission loss and noise frequency as the criterion of preparation of acoustic liner data acquisition,analysis and control system,and design the corresponding driving voltage control circuit based on photosensitive resistance.The test results show that when the acquisition card output voltage of 2.1V to 4.0V,the driving circuit output voltage of 0V to 400 V,automatically adjust the driving voltage to achieve the acoustic liner.Finally,the testing device of acoustic lining system has been constructed.The silencing effect respectively processed tested 35 mm piezoelectric acoustic liner and 50 mm double chamber piezoelectric acoustic liner,the results show that the 50 mm double chamber piezoelectric acoustic lining has the band offset greater noise.At the voltage range of 0V-200 V,the frequency band can be offset by about 200 Hz.In addition,the design of adaptive acoustic liner control system,using 35 mm piezoelectric acoustic liner as an example,the frequency range of 750 Hz to 780 Hz,the noise reduction for 5dB.The designed adaptive control system can change the silencer frequency band of the tunable piezoelectric acoustic liner so that it changes with the noise frequency,which means widening the silencer frequency range of the acoustic liner.