压力系数分析法的低噪声鼻锥设计

Low-noise Nose-cone Design Using Pressure Coefficient Analysis Method

在航空声学风洞内进行气流内的噪声测量时,需要在传声器前端安装鼻锥,以降低流场波动对传声器振膜的干扰噪声。目前使用的鼻锥,当流速超过40 m/s时,自噪声大幅度提高,因而无法用于更高速度的流场测试。利用一种鼻锥低噪声设计的分析方法,分析鼻锥表面的压力系数分布规律,并提出一种降低鼻锥自噪声的改进形式,降低不稳定的静态压力的干扰。将鼻锥的透声孔设置在压力稳定区域,可减少流场内不稳定压力波动对被测声波信号的干扰,提高测试结果的准确性,满足更高速度的流场测试需求。

In airflow noise measurements in aero-acoustic wind tunnel, microphone must be jacketed with nose-cone to reduce the disturbance of the air-flow field fluctuation noise to the microphone. However, this method does not work when the flow velocity exceeds 40 m/s since the self-noise of the nose-cone increases dramatically. In this paper, the pressure distribution on the nose-cone surface was analyzed. On this basis, a modified nose-cone shape was proposed which can reduce the disturbance of the unstable static pressure so that the self-noise of the nose-cone can be diminished. By setting the sound-penetrating holes in the steady pressure region, the disturbance of the instable pressure fluctuation to the acoustic signal can be diminished. Therefore, the measurement accuracy is raised and can satisfy the requirements of higher speed wind tunnel tests.