Effect of streamwise vane treatments on the noise reduction performance of trailing edge serrations under aerodynamic loading conditions

Trailing edge serrations have shown remarkable ability to reduce noise, but their effectiveness can be significantly impacted by flow misalignment, particularly under aerodynamic loading conditions. This paper presents a comprehensive study on the effect of incorporating streamwise vane treatments at the root of the trailing edge serrations on its noise reduction performance. Experiments were performed on a 100 mm chord NACA 0012 wing model with sawtooth type trailing edge serration. The aeroacoustic performance was investigated for serrations with non-zero flap angle at various angles of attack between −5° and 8.5°. The findings reveal that streamwise vanes can reduce the high-frequency noise by over 5 dB when placed at the root. Furthermore, particle image velocimetry measurements in the wall-normal plane demonstrate a significant decrease in cross-flow and turbulence generation when the treatment was placed near the root of serrations. In addition, the load measurements indicate no noticeable variation in the lift coefficient and up to 6% increase in the drag coefficients in the pre-stall region.