飞行器结构噪声致振试验及声振耦合响应分析

Noise-Induced Vibration Experiment of Aircraft Structure and Vibro-Acoustic Coupling Response Analysis

以高超声速飞行器X-43A为研究对象,建立其有限元结构模型,在动力学实验室进行飞行器结构模型的固有频率测试,通过固有频率计算与试验结果对比,二者误差在1%左右,这表明所建立的结构有限元模型是比较准确的.在高声强混响室进行飞行器结构噪声致振试验,得到飞行器结构测点加速度功率谱密度(power spectral density,PSD)和舱内声场噪声声压级,通过声振耦合数值模拟计算结果与试验值对比.结果表明:数值模拟计算方法对振动噪声环境预测是比较可靠的,结构振动响应与舱内噪声响应的有限元分析与试验结果趋势上较为一致,低频段吻合较好;高频外噪声场引起的飞行器弹性腔体结构振动占据结构振动响应的主要成分,尤其是以结构低阶振动为主,而外噪声场传递到封闭腔体内的噪声也主要是通过结构腔体弹性壁板的低阶振动传播,即使外噪声激励是宽频的,封闭舱内响应噪声的频率主分量仍然是结构的低阶模态振动.

Aimed at the hypersonic aircraft X-43A in the research, the FE model was estab- lished. Natural frequency testing of the aircraft structure model was performed. The numerical values of natural frequency were compared with the experiment results, with errors at about 1%, which showed that the FE model of the aircraft was correct. A noise-induced vibration ex- periment of the aircraft model was completed in the high intensity sound laboratory, which could obtain the results of PSD and noise pressure. Comparison of the numerical simulation val- ues with the experiment results shows that the method of numerical simulation is reliable in prediction of the vibration and noise environment of the aircraft cabin. The trend of the numeri- cal vibro-acoustic response is well consistent with that of the test results： there is little differ- ence in low-frequency range. The elastic cavity structural vibration of the aircraft model caused by high-frequency noise field outside the cavity makes the main components of structural vibra- tion, especially for the low-order structural vibration. Noise in the aircraft cabin transmitted from the outer noise field is through the low-order vibration of the aircraft shell. The main components of the response noise frequencies in the closed cabin belong to structural low-order modal vibration, even if the noise excitation outside the cabin is broadband.