“移频降噪”理论研究及灵敏度分析

RESEARCH ON THE THECNIQUE OF FREQUENCY SHIFTING FOR NOISE REDUCTION AND IT’S SENSIBILITY ANALYSIS

通过分析封闭、半封闭空间中气体的声学特性,针对当其固有声学频率与激振频率一致时,由于气体共振产生的共鸣音,提出了移频降噪理论。即通过合理分隔封闭、半封闭空间,以改变内部气体的固有频率,使之远离激振频率,从而十分有效地降低了噪声。利用有限元分析软件对试验台的固有频率进行计算机仿真模拟,获得了加入隔板后封闭、半封闭空间试验台内气体固有频率的偏移数据,给出隔板设计的方案。并通过电-声类比法推导了固有频率对分隔空间的隔板的各个几何参数的灵敏度公式,给出了隔板结构设计的理论依据,阐明了移频降噪理论的可行性。

The technique of frequency shifting for noise reduction is introduced. When a hermetic or halt-hermetic space is partitioned by a clapboard, the acoustic eigen frequencies of the gas inside would be changed to far from the exciting frequencies, so that the noise due to gas syntony would be reduced considerably. The acoustic eigen frequencies of the hermetic and half-hermetic spaces and its change with dimensions of the clapborad are simulated. The sensibility expression for the eigen frequencies which are determined by geometric dimensions of the clapboard is established.