Experimental investigation on aerodynamic noise characteristics of slat deflection rotating around a fixed axis

To study the influence of the deflection variation of the leading-edge slat on aerodynamic noise, the experimental investigation of the canonical MD30P30N three-element high-lift airfoil configuration was carried out in D5 areo-acoustic wind tunnel at Beihang University. A novel Kevlar-walled closed test section design has been applied, the deflection angle of the slat was changed to obtain the spectrum of the far field noise during the deflection process. Combined with the steady-state flow field obtained by the 2-D RANS numerical simulation, the flow field and aerodynamic noise characteristics were analyzed, and the effect of the change of the deflection angle on the slat aerodynamic noise was investigated. Moreover, microphone array technology was used to identify the noise source location and strength in this research. The numerical results show that the reduction of the slat deflection angle causes the main wing leading edge to continue penetrating into the slat cove region, the size of the ‘recirculation’ zone inside the cavity is obviously smaller, and the position of the reattachment point of shear layer is also moved forward. These changes in the flow field inevitably lead to different noise sources and far-field noise of the leading-edge slat.