前缘下垂远场低频宽频噪声特性

Characteristics of low frequency broadband noise for leading-edge droop nose measured in a far-field

为了研究前缘下垂远场噪声特性,在北京航空航天大学D5风洞内开展前缘下垂增升构型远场噪声特性试验研究,并利用计算流体力学的方法补充提供增升构型附近流场信息。增升构型模型为前缘下垂搭配后缘襟翼,为了消除襟翼噪声干扰,后缘襟翼收起。研究表明,前缘下垂增升构型远场噪声频谱以宽频噪声为主。随着来流速度的增加,宽频幅值逐渐增加。其中,低频(200~400Hz)宽频噪声幅值经过马赫数5次方归一化后吻合良好。随着迎角的增加,中高频宽频幅值变化不大,但是,低频宽频噪声幅值变化明显,先降低再增加。通过分析在不同迎角下,有效迎风面积、压力面DSM Dyneema布变形以及两者共同对远场噪声幅值的影响,发现远场低频宽频噪声幅值变化规律与模型附近流场变化有关。

An experimental study on the far-field noise characteristics of leading-edge droop nose is conducted in Beihang University D5 wind tunnel.The computational fluid dynamics method is used to obtain the flow information near the high-lift device.A two-dimensional high-lift configuration model with a leading-edge droop nose is used,and the trailing-edge flap is stowed to eliminate the flap noise interference.The results show that broadband noise dominates the far-field noise spectrum of the high-lift configuration with a leading-edge droop nose.With the increase of freestream velocity,the broadband amplitude increases gradually.Among that,the amplitude of the low frequency(200-400 Hz)broadband noise is well-matched after normalization by the 5 Mach number power law.With the increase of angle of attack,the mid to high frequency broadband noise does not significantly change,but the amplitude of low frequency broadband noise changes significantly that first decreases and then increases.The analyses of the effect of effective windward area,DSM cloth deformation and their combined effects on the far-field noise amplitude at different angles of attack find that the amplitude variation of the low frequency broadband noise is related to the flow characteristics near the model.