任意边界条件下弹性背腔膜式消声器声学特性分析

Acoustic characteristics analysis of elastic back cavity membrane muffler under arbitrary boundary conditions

弹性背腔膜式消声器由弹性背腔以及弹性内膜组成,通过声场与弹性内膜及弹性外膜的耦合作用,降低消声器下游的透射声能,在低频具有较好的宽带消声效果。为求解任意边界条件下的弹性背腔膜式消声器的传递损失,基于能量原理,建立了弹性背腔膜式消声器的声振耦合模型。采用边界弹簧约束来实现弹性膜的任意边界条件,进而分析边界约束对传递损失特性的影响。结果表明,理论计算结果与有限元结果吻合良好;结构边界约束对系统声学特性影响显著,增强外膜边界约束,能获得低频宽带消声效果;减弱内膜边界约束,能使最低消声频率向低频移动。

Elastic back cavity membrane muffler is composed of an elastic back cavity and an elastic inner membrane.Through coupling action of sound field with elastic inner membrane and elastic outer membrane,transmitted sound energy of downstream of muffler is reduced,and it has a better broadband noise reduction effect at low frequencies.Here,to solve the transfer loss of an elastic back cavity membrane muffler under arbitrary boundary conditions,a sound-vibration coupled model of an elastic back cavity membrane muffler was established based on the energy principle.Boundary spring constraints was used to realize arbitrary boundary conditions of elastic membranes,and then analyze effects of boundary constraints on transfer loss characteristics.The results showed that the theoretical calculation results agree well with the finite element calculation results;structural boundary constraints affect the system’s acoustic characteristics significantly;enhancing outer membrane boundary constraints can obtain low-frequency broadband noise reduction effect;weakening inner membrane boundary constraints can shift the lowest noise reduction frequency towards lower frequencies.