The Acoustic Performance Study Of The Piezoelectric Acoustic Liners With Heteromorphic Chamber

The acoustic lining is one of the most effective ways to suppress the noise of aero-space aircraft turbofan engines.Due to the geometric parameters and material properties of its own structure,traditional acoustic liners can only restrain the noise of the specific frequency band.Once the noise frequency exceeds this range,the suppression effect will decrease obviously.In this paper,based on the traditional acoustic lining,we deeply analyze the acoustic lining cavity,use the inverse piezoelectric effect of piezoelectric vibrator to make it as the backing cavity of acoustic liners,and put forward different types of new sound lining structures.First of all,based on the theory of plane wave and the theory of transfer matrix,this paper puts forward eight kings of acoustic lining chambers with different profile types,establishes the acoustic physical model of the acoustic lining,derives the analytical expressions for the transmission loss of eight kinds of special shaped cavity acoustic liners,and the simulation theory is compared and verified in turn.The comparison results show that the maximum difference between the eight analytical expressions of the transfer loss and the simulation results is only 10 Hz,and the simulation curve is almost coincided with the theoretical calculation curve,and the correctness of the transfer loss calculation formula based on the plane wave theory is verified.Secondly,the acoustic finite element simulation of eight special cavity piezoelectric acoustic lining structures under the same size is carried out in turn,and the simulation results are compared with the cylindrical cavity piezoelectric acoustic linings.The maximum frequency offset is 121 Hz,and the frequency offset of the cylindrical cavity under the same size is 60 Hz.The results show that the above eight kinds of special-shaped cavity piezoelectric acoustic lining structure and cylindrical cavity acoustic lining structure have different degrees of improvement in frequency offset.After that,the acoustic experimental platform was built,and one kind of cavity type acoustic lining was processed by 3D printing technology,and the performance test was carried out.The experimental data collected by the experiment are collected and collected.The results show that this type of acoustic liner can effectively suppress the noise from 335 Hz to 415 Hz under the action of 0-200 V driving voltage.Finally,the above eight special-shaped cavity acoustic lining units are improved.Following the analysis flow of the second chapter,the finite element simulation of the new structure is carried out sequentially.The above simulation results are compared with the transmission loss curves of the unimproved cavity acoustic lining.It is found that the initial frequency increases and the frequency offset increases with the improvement of the acoustic lining compared with the unimproved acoustic lining.After in-depth study,it is found that the maximum percentage of the hyperbolic acoustic liner frequency offset is 15.4%,the sine curve is 12.4%,and the cylindrical cavity is only 9.4%.The volume of hyperbolic cavity is the largest in the eight kinds of special-shaped cavity,the smallest in the sinusoidal cavity and the smallest in the cylinder.It is shown that the noise suppression of the special shaped cavity can achieve a wider frequency band than the cylindrical acoustic lining at the same size.