基于Helmholtz共振腔的组合结构带隙特性研究

Helmholtz共振结构的声屏障在控制道路交通噪声方面具有潜在的应用前景。为有效提高特定频段的噪声控制,本文设计了一种主腔连接4个副腔的Helmholtz复合共振腔结构。首先,利用有限元法对共振腔模型进行计算分析,得出共振腔的禁带结构和声传播损耗曲线;其次,利用声-电类比法建立了Helmholtz共振腔的等效电路,并对带隙的产生机理进行分析;最后,讨论了结构参数对Helmholtz共振腔带隙的影响,并分析这些参数对第一带隙下限的影响机理。结果表明:声波在Helmholtz共振腔单元间同时存在相互作用和腔内谐振效应,能在晶格常数为60 mm的情况下获得范围为432.43~663.98 Hz的第一带隙,比单、双开口圆环带隙起始频率更低,且大部分频率范围的隔声量达到10 dB以上,最大隔声量超过90 dB,表现出良好的中频隔声特性;等效电路模型与有限元法的计算值的最大误差不超过10%且平均误差低于5%,建立的等效模型是合理的;结构参数对于带隙有较大影响,主要是通过影响共振腔内部气体的体积从而影响带隙。

Band Gap Characteristics of Composite Structure Based on Helmholtz Resonator

Acoustic barriers with Helmholtz resonant structures have potential in controlling traffic road noise. In order to effectively improve the noise control in a specific frequency band, a Helmholtz composite resonator structure with four secondary resonators is designed in this paper. Firstly, the finite element method is used to calculate and analyze the resonator model, and the band gap structure and sound transmission loss curve of the resonator are obtained. Secondly, the equivalent circuit of Helmholtz resonator is established by acoustic-electric analogy method, and the generation mechanism of band gap is analyzed. Finally, the influence of structural parameters on the band gap of Helmholtz resonator is discussed, and the mechanism of these parameters on the lower limit of the first band gap is analyzed. The results show that the sound wave has interaction and cavity resonance effect among the Helmholtz cavity elements at the same time. The first band gap in the range of 432.43 Hz to 663.98 Hz can be obtained when the lattice constant is 60 mm, which is lower than the initial frequency of the band gap of the opening ring. The sound insulation in most frequency ranges reaches more than 10 dB, and the maximum sound insulation exceeds 90 dB, which shows better intermediate frequency sound insulation characteristics. The maximum error between the equivalent circuit model and the calculated value of the finite element method does not exceed 10% and the average error is less than 5%, the established equivalent model is reasonable. The structure parameters have a great influence on the band gap by affecting the volume of gas in the cavity.