Articulated Model-Scale Slat Gap Filler for Airframe Noise Reduction

High-lift systems on commercial aircraft can significantly increase aircraft noise during approach and landing phases of flight. The leading-edge slat is a major source of aeroacoustic noise due to its complex geometry. The slat-gap filler (SGF) is a device that blocks airflow through the gap between the trailing edge of the slat and the main wing, eliminating most noise emission from the slat. However, flow through the slat gap delays separation and increases maximum achievable lift coefficient. This increased lift is not required under normal operating conditions, but the slat gap may need to be opened in emergency conditions. This "gap-on-demand" capability is often excluded from model-scale aerodynamic testing as models are not articulated. This work presents the development and test of an articulated 1/16-scale infinite-wing (2D) variant of the NASA High Lift Common Research Model (CRM-HL) equipped with a deployable superelastic shape memory alloy SGF that is capable of emergency retraction. The completed model is tested for structural, aerodynamic, and aeroacoustic performance. Lift, drag, and pressure coefficient data are presented, along with acoustic spectra and beamformed acoustic source maps from an in-house scanning acoustic array. Rapid retraction of the SGF to open the slat gap in emergency conditions will be demonstrated.