Noise reduction for transonic blade-vortex interactions

Several ideas for noise reduction of transonic blade-vortex interactions (BVI) are being introduced and tested using numerical simulation. The model used is the two-dimensional high frequency transonic small disturbance equation with regions of distributed vorticity (VTRAN2 code). The far-field noise signals are obtained by using the Kirchhoff method which extends the numerical two-dimensional near-field aerodynamic results to the linear acoustic three-dimensional far-field. The BVI noise mechanisms are explained and the effects of vortex type and strength, and angle of attack are studied. Particularly, airfoil shape modifications which lead to noise reduction are investigated here. The results presented are expected to be helpful for better understanding of the nature of the BVI noise and better blade design.