On the use of leading-edge serrations for noise control in a tandem airfoil configuration

SH. S. Vemuri*, Xiao Liu, B. Zang, Mahdi Azarpeyvand

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Abstract

Passive noise control for a tandem NACA 65-710 airfoil configuration is experimentally investigated by applying leading-edge serrations on the rear airfoil. With a sliding side-plate mechanism that allows the rear airfoil to move in the vertical direction relative to the front airfoil, the position of maximum turbulence interaction noise is first identified from the far-field noise measurements. Subsequently, detailed static surface pressure distribution and unsteady surface pressure fluctuations are acquired to shed more light on the physical phenomenon and underlying noise-reduction mechanism of the leading-edge serrations. The far-field noise measurements confirm that a notable turbulence interaction noise reduction can be achieved from 600Hz < f < 3000Hz, agreeing well with the previous literature on the effectiveness of the leading-edge serrations. The near-field hydrodynamic analyses obtained using remote-sensing techniques of the fluctuating pressure fields over the airfoil show that a significant reduction in the surface pressure fluctuation levels up to 20dB/Hz can be observed at the serrated-tip plane of the rear serrated airfoil close to the leading-edge regions, over the range of frequencies investigated. Although reduction can also be observed on the serrated-root plane, the magnitude is much less significant. The present results suggest that the modification of the unsteady loading on the rear airfoil by the leading-edge serrations plays a crucial role on the reduction of turbulence interaction noise in the tandem airfoil configuration, which may find practical application for the noise reduction from aerodynamic systems involving rows of airfoils, such as contra-rotating open rotors and outlet guide vanes.
Original languageEnglish
Article number 077102 (2020)
Number of pages18
JournalPhysics of Fluids
Volume32
Early online date1 Jul 2020
DOIs
Publication statusE-pub ahead of print - 1 Jul 2020

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