弹性空腔流致噪声/结构振动特性试验

Test on interactions between aeroacoustic noise and structural vibration in elastic cavity flow

高速空腔中经常存在高强度且多频率分量的流致噪声,空腔噪声与结构振动之间耦合效应严重,甚至可能发生结构共振。为此,在0.6m×0.6m高速风洞中,通过调整空腔底板厚度,改变其结构固有频率,模拟空腔流致噪声/振动相互作用。利用脉动压力和振动加速度测试技术,获取亚跨声速条件下,弹性空腔流致噪声特性及其结构振动响应特性。马赫数变化范围为0.6~1.2。结果表明,当振动强度较弱时,结构振动对空腔噪声影响较小,而空腔噪声对结构振动影响较大,在噪声载荷主频位置,振动谱出现峰值并且噪声/振动相关性达到最强;此外,空腔结构振动还与其固有频率特性密切相关,振动主要以低阶模态为主。

Coupling between aeroacoustic noise loads and structural vibration in cavity flow-induced oscillation may bring about severe damage to aircraft,especially when structural resonance occurs.To study the coupling mechanism,elastic cavity tests are performed in a high-speed wind tunnel with 0.6m×0.6mcross-section.The natural frequency of the elastic cavity structure can be adjusted by changing the thickness of its floor.Noise and vibration transducers are employed in the tests to obtain acoustic noise loads and structural vibrations.The Mach number ranges from 0.6 to 1.2.It is shown that under the current conditions,structural vibration has little effect on cavity noise,while cavity noise has an important influence on structural vibration.At the main frequency position of cavity noise,power spectral density of structural vibration peaks and correlation of noise/vibration are the strongest.In addition,structural vibration is also closely related to the natural frequency of the cavity,and vibration is dominated by the low-order mode.