This paper presents an experimental study on passive noise control for a tandem NACA65-710 airfoil conﬁguration by applying serrations to the leading edge of the rear airfoil. A comprehensive study has been performed for different airfoil gap distances, angles of attack and velocities. Wake-proﬁle measurements on an isolated airfoil are used to determine the maximum turbulence intensity locations for the optimal positioning of the rear airfoil for near-ﬁeld and far-ﬁeld acoustic measurements. The far-ﬁeld noise measurements and noise directivity analysis have demonstrated that the use of leading-edge serrations can lead to signiﬁcant noise reduction from the tandem airfoil conﬁguration. The near-ﬁeld hydrodynamic analysis obtained using remote-sensing of the ﬂuctuating pressure ﬁeld overthe airfoil has shown that the use of leading-edge serrations causes signiﬁcant reduction in the unsteady aerodynamic load acting on the airfoil, particularly along the serration tip plane. This is believed to be due to a strong ﬂow separation from the serration tip region. Further hydrodynamic ﬁeld and near-ﬁeld to far-ﬁeld coherence investigations are planned to better understand the mechanisms leading to the reduction of the far-ﬁeld noise.
|Name||25th AIAA/CEAS Aeroacoustics Conference|