低亚声速大宽高比矩形射流远场噪声特性研究

目的 将空气幕自噪声问题简化为低亚声速大宽高比矩形射流噪声问题，并研究其特性。方法 设计低亚声速大宽高比矩形射流试验台，并系统地研究主要噪声来源以及射流速度、方位角、宽高比等参数对远场噪声的影响规律。结果 低亚声速大宽高比矩形射流远场噪声主要集中在低频部分(500 Hz以内)，除宽高比为14的矩形射流噪声因声共振现象导致某些频率附近存在模态噪声峰值，从而不符合噪声频谱归一化规律外，其他低亚声速大宽高比矩形射流远场噪声频谱都符合如下规律，即射流噪声总声压级大致与射流速度的7.4次方成正比，与矩形喷管宽度的1.6次方成正比。结论 低亚声速大宽高比矩形射流远场噪声归一化规律可为深入了解空气幕自噪声特性提供理论指导。

Far Field Noise Characteristics of High Aspect-ratio Rectangular Jet with Low Subsonic Velocity

The air curtain is a new active noise control technology which can effectively reduce the aerodynamic noise of the landing gear. However, the development of the air curtain is limited by its self-noise, which can be simplified as a high aspect-ratio rectangular jet noise problem with low subsonic speed. In this paper, the high aspect-ratio rectangular jet test rig with low subsonic velocity was designed specially, and the main noise sources and the effect of jet velocity, azimuth angle, aspect ratio and other parameters on far field noise were studied systematically. It was found that the far field noise of high aspect-ratio rectangular jet with low subsonic velocity was mainly concentrated on the low frequency part (<500 Hz). Except for the rectangular jet noise with the aspect-ratio of 14, which did not conform to the noise spectrum normalization law, because it had a modal noise peak near some frequencies caused by acoustic resonance phenomenon, other far field noise spectrum of the high aspect-ratio rectangular jet with a low subsonic velocity all conformed to the following law, that the overall sound pressure level of jet noise was roughly proportional to 7.4 power of the jet velocity and 1.6 power of the rectangular nozzle width. The normalization law of far field noise for high aspect-ratio rectangular jet with low subsonic velocity can provide theoretical guidance for further understanding the self-noise characteristics of air curtain.