Analysis on aeroacoustic characteristic of the two-dimensional parallel blade-vortex interaction

A thorough understanding of the impulsive noise characteristics of the Blade-Vortex Interaction (BVI) is of great significance to its noise control.The two-dimensional,parallel BVI aeroacoustic at low Reynolds number was calculated by adopting the Direct Noise Computation (DNC) approach.The noise generation mechanism,propagation and attenuation laws were studied.Results show that when the vortex approaches and passes by the leading edge of the airfoil,two sudden changes of pressure near the leading edge of the airfoil occur with different intensity,which results in aerodynamic changes of the airfoil simultaneously giving rise to the dipole directional impulsive sound waves.The weaker sudden change of pressure can radiate sound waves more efficiently.By analyzing the sound fields of four different incoming velocities,it is found that the peak sound pressure of upper and lower far fields is inversely proportional to the propagation distance,and proportional to the product of the third power of the incoming velocity and the fluctuation amplitude of lift coefficient.The formula for calculating the peak sound pressure in the far field is obtained,which provides another way for predicting the far-field sound pressure of BVI.