Experimental Investigation of Flow Around Three-Element High-Lift Airfoil with Morphing Fillers

Aerodynamic and aeroacoustic measurements of a three-element airfoil (30P30N) fitted with various slat cove fillers and droop-slat configuration were carried out for a wide range of angles of attack and Reynolds numbers (4.6 × 10⁵ to 1.1 × 10⁶). The results are presented for static and unsteady surface pressure measurements and flow visualisation using particle image velocimetry (PIV). Mean surface pressure measurement results show that the aerodynamic performances were affected with the application of slat cove filler especially if its profile was not apt for the operating conditions. The PIV results clearly show that a highly energised fixed vorticity was present within the slat cove region of the baseline case and it was eliminated by the application of slat cove filler. A smaller vorticity develops as a result of the slat cove filler and the vortices size changes with increase in angle of attack. The wall-pressure spectra acquired using the flush mounted transducers shows narrowband and broadband components for the baseline case. The application of slat cove fillers completely eliminated the narrowband spectra generated by the vortices inside the slat cove. However, the slat cove filler appears to increase the overall broadband at low and mid-frequency range in the airfoil near-field. Results confirmed the great aerodynamic and aero-acoustic potential of the morphing structures for high-lift devices, which is one of the highly sought candidate for the next generation aircraft control surfaces.