Noise control in tandem airfoil configurations using leading-edge serrations on the front airfoil

Abstract

Passive noise control of a tandem NACA6412 airfoil is experimentally studied by applying sinusoidal serrations to the leading-edge of the front airfoil. The position of the rear airfoil in the vertical gap direction is adjusted to identify the position that results in the maximum reduction in far-field noise. Subsequently, detailed unsteady flow characteristics in the flow field are measured using particle image velocimetry (PIV). The far-field noise results indicate that, at the position of optimal noise reduction, the application of leading-edge serrations to the front airfoil significantly reduces turbulence interaction noise in the frequency range of \(\text{700 }\text{Hz} \le f\le {2000} \text{Hz}\), with a maximum reduction of up to 10 dB. Analysis of the PIV results shows that leading-edge serrations can significantly decrease turbulence intensity and vorticity in the wake of the front airfoil, while also narrowing the influence range of vortex shedding and turbulence. Therefore, the positioning of the front and rear airfoils has a strong impact on the variation in turbulence interaction noise. The research concludes by emphasizing the effect of leading-edge serrations on the wake of airfoils. These findings can be applied to reduce noise in rotating machinery, such as guide blade rows, fan blade rows, and turbine blade rows.