| dc.description.abstract | Aircraft noise is a source of disruption and annoyance to those living within close proximity to airports. Airframe noise is a main contributor to the overall noise level created by aircraft during approach and landing. One of the major sources of acoustic noise is the leading-edge slat, a high lift device on general transport aircraft. The slat has complex geometry from the dual role they perform on the wing leading edge during flight. During takeoff and landing, high lift devices are deployed to provide supplemental lift at low velocity. During cruise, additional camber and separated lifting surfaces are unnecessary to produce the required lift and the devices are retracted against the main wing, with the slat providing a cove with which the wing leading edge can fit into, creating a more efficient airfoil. Because of this complex geometry, when the slat deploys, flow on the pressure side of the wing separates and circulates within the cove of the slat. There are several known noise production mechanisms in this flow field. The slat cove filler (SCF) has been proven to be an effective tool in the reduction of unsteadiness in the flow, and thus noise radiated to the far field. The current SCF utilizes a shape memory alloy (SMA) insert that redirects flow along an acoustically advantageous path, avoiding circulation and reducing noise. Using the Texas A&M University 3 ft x 4 ft wind tunnel, the noise reduction capabilities of an SMA-based SCF have been proven for the first time experimentally across multiple flight conditions (angle of attack, %-deployment, and flow velocity). Structural assessments were conducted as well using non-intrusive means to obtain displacement and geometric information on the SCF under flow. Aerodynamic measures were compared between experimental setups with and without the SCF in place, with minor variations in pressure, lift, and drag distribution when the high lift devices were fully deployed. Additional acoustic savings may be discovered in future research by altering the geometry of the SCF to reflect the flow conditions specific to the length and velocity scale. | en |
