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针对航空发动机产生低频噪声过大影响飞行员完成作战任务的问题,本文提出了一种新型局域共振复合单元结构模型。采用有限元法对局域共振结构带隙生成机理进行深入分析。结果显示:共振频率的位置是由局域共振模态的固有频率决定,且局域化程度与基体之间的相互耦合作用的强度有关;通过扩充后的局域共振复合结构单元,可以实现多重共振,打开多条低频共振带隙。通过对局域共振复合结构单元结构的带隙机理和局域共振特性进行仿真分析。结果表明:该复合单元结构在250 Hz以下的频率范围打开超过68.54%的共振带隙,最低频率降低至53.6 Hz,即在航空发动机低频降噪效果良好,在大型军机舱室低频降噪具有重要的理论意义和工程应用价值,显著提高作战效率。
Aiming at the problem that the aero-engine generates low-frequency noise and affects the pilot’s mission, this paper presents a new model of local resonant composite cell structure. Finite element method is used to analyze the mechanism of bandgap generation in local resonant structure. The results show that the position of resonance frequency is determined by the natural frequency of local resonance mode and the degree of localization is related to the intensity of the mutual coupling between the substrates. By using the extended local resonance composite structure unit, Resonance, open a number of low frequency resonance band gap. The bandgap mechanism and local resonance characteristics of the local resonant composite structure are simulated and analyzed. The results show that the composite unit structure opens the resonance band gap exceeding 68.54% at a frequency range below 250 Hz and the minimum frequency is reduced to 53.6 Hz, ie, the low-frequency noise reduction effect of the aero-engine is good and low-frequency noise reduction in large military aircraft cabins is important Theoretical significance and engineering application value, significantly improve operational efficiency.