空腔噪声的马赫数敏感性研究

敏感度分析在评估参数的重要程度以及计算不确定度方面具有重要作用。通过风洞试验开展了亚跨超声速下的空腔噪声马赫数敏感性研究。亚跨声速下，通过调节调压阀的开度改变马赫数，马赫数名义增量为0.010。超声速下，通过改变模型迎角实现马赫数的连续变化，迎角增量为1°。利用总压耙测量空腔入口马赫数。结果表明:空腔后部测点脉动压力系数在亚跨声速下随着马赫数的增加而增加，而在超声速下随着马赫数的增加而减小。跨声速下，脉动压力系数对马赫数的敏感性导数最大。不考虑模态切换的情况下，不同速域的主导声模态St对马赫数的敏感性导数均为负数。主导声模态谱峰在亚声速下随着马赫数的增加而增加，而在超声速下随着马赫数的增加而降低。敏感度研究结果不仅可用于内埋武器舱气动噪声载荷的不确定度评估，也有助于更好地认识空腔噪声特性。

Mach number sensitivity analysis of cavity noise

Sensitivity analysis plays an important role in assessing the importance of parameters and calculating the uncertainty. Mach number sensitivity analysis of cavity noise at subsonic, transonic and supersonic speed has been investigated by wind tunnel experiments in this study. At subsonic speed, the Mach number is changed by adjusting the opening of the valve, and the nominal increment of the Mach number is 0.01.At supersonic speed, the continuous change of the Mach number is achieved by changing the angle of attack of the model, and the increment of angle of attack is 1 degree. The experimental results show that the fluctuating pressure coefficient at the rear of the cavity increases with the increase of the Mach number at the subsonic speed, while decreases with the increase of the Mach number at the supersonic speed. At transonic speed, the fluctuating pressure coefficient has the largest sensitivity derivative to the Mach number. In the case of modal switching, the derivative of St to Mach number for the dominant acoustic mode is negative. The peak value of the dominant acoustic mode's power spectral density increases with the increase of Mach number at subsonic speed, while decreases at supersonic speed. The obtained sensitivity results can be used not only for the uncertainty assessment of the aerodynamic noise load in the embedded weapon bay, but also for a better understanding of the cavity noise characteristics.