Metasurface acoustic liner of engine based on asymmetric absorber br

In order to solve the problem of low frequency noise of engine, based on the principle of dual portasymmetric sound absorber, a kind of gradually changing size sound absorbing metasurface is designed to reducethe noise of engine acoustic liner. Firstly, the theoretical analysis model and simulation analysis model of theasymmetric resonance sound absorber are established, the noise reduction mechanism is revealed, and theinfluencing factors of the noise reduction effect are analyzed. Then an acoustic metasurface acoustic liner isdesigned based on the asymmetric resonance sound absorber. The noise reduction effect of the acoustic liner isanalyzed in depth by using three methods: full model theoretical calculation, equivalent impedance theoreticalcalculation and COMSOL finite element simulation. Then, the parameters of this structure are optimized, andthe influence of flow velocity on the noise reduction effect is considered by using the full model theoreticalcalculation and equivalent impedance theoretical calculation. The research results show that the acousticmetasurface acoustic liner designed based on asymmetric sound absorber can achieve noise reduction effect ofmore than 3 dB in a frequency band range from 252 to 692 Hz when the thickness is only 2.5 cm (only 1/54 ofthe corresponding wavelength of 252 Hz), which provides a new idea for designing engine noise reduction

Automated summary

This study proposes a gradually changing size sound absorbing metasurface based on the dual port asymmetric sound absorber principle to tackle the problem of low frequency engine noise. Theoretical and simulation models are established to analyze the noise reduction mechanism and influencing factors. An acoustic metasurface acoustic liner is designed and analyzed using three methods. The research demonstrates that the designed acoustic liner can achieve a noise reduction effect of over 3 dB in a frequency band range of 252 to 692 Hz.