亚临界雷诺数圆柱绕流远场气动噪声实验研究

针对亚临界雷诺数下圆柱绕流的气动噪声问题,在北京航空航天大学D5气动声学风洞中进行了圆柱绕流远场气动噪声的实验研究。在D5气动声学风洞实验段不同来流条件下,测量消声室中距离圆柱不同位置的自由场传声器的远场声压信号,经过快速傅里叶变换(FFT)获得亚临界雷诺数下圆柱绕流气动噪声随来流速度、接收点距离的变化规律。实验结果表明:圆柱绕流的远场气动噪声在垂直气流方向最大,随着偏离垂直方向角度的增大噪声逐渐减小,属于典型的偶极子噪声源辐射特性;远场气动噪声近似与来流速度的6次方成正比,与接收点到圆柱中心距离的2次方成反比,这说明偶极子类型的噪声源是圆柱绕流的主要噪声源。 

Far-field aeroacoustic experimental study of flow around a circular cylinder at subcritical Reynolds number

To study the aeroacoustics of the flow around a circular cylinder at subcritical Reynolds number, the experimental investigation of far-field aerodynamic noise generated from flow past a circular cylinder was carried out in D5 aeroacoustic wind tunnel at Beihang University. Under variable flow conditions in the D5 test section, the signal of the sound pressure obtained from the free-field microphones at different positions in the anechoic chamber was measured. The dependence of far-field noise on free stream velocity and receiver position was acquired with the fast Fourier transform(FFT). With the qualitative and quantitative analysis of the aeroacoustic characteristics, the experimental results validate that the noise emitted from the circular cylinder is the largest in the direction vertical to the flow and decreases with the angle increasing, belonging to the characteristics of the sound radiated from a dipole sound source. The far-field aerodynamic noise generated from the cylinder is proportional to the sixth power of flow speed and inversely proportional to the twice power of the distance between the receiver and the center of the circular cylinder, confirming the domination of the dipolar noise source.