介质速度对有限长导管内外声场影响研究

Effect of fluid velocity on acoustic field of a finite-length duct

利用导管声波模态理论给出导管声波截止频率;采用边界元方法计算不同流速条件下、不同导管半径及导管半径波长比时的导管内外声场。结果表明,对相同的导管和声源,流速的增加会使截止频率减小;因介质速度影响,导管侧壁及下游管口方向声场能量会向上游管口方向转移,且在低频、高流速条件下,此规律更明显。

In order to investigate impact of fluid velocity on acoustic field of a finite-length duct, the cut-off frequency was deduced based on the acoustic modal theory. Then, the interior and exterior acoustic fields of the finite-length duct were calculated with the boundary element method under conditions of various fluid velocities, duct radiuses and radius-to-wavelength ratios. It was shown that for the identical duct and sound source, the cut-off frequency decreases with increase in fluid velocity; the sound energy at the side wall and the downstream nozzle of the duct moves upwards due to the influence of fluid velocity; this law is more obvious at lower frequency or larger fluid velocity.