Autonomous Slat-Cove Filler Device

NASA Langley designed the shape memory alloy slat-cove filler to provide significant broad-band noise reduction to any aircraft wing structure that has a leading-edge, high-lift device and that is distinct from the main-wing element. The design can be retrofitted to existing aircraft structures and can be easily incorporated into the existing or future designs for aircraft wing structures. The concept involves very few components, requires no additional mechanical support from pneumatic or hydraulic systems, and makes use of existing slat-actuation systems for retraction. The design is autonomous, simple, and constitutes low-weight addition. The concept is also considered fail-safe because the lift would not be diminished in the event that the slat cove filler failed to deploy. Several advancements have been devised to accommodate complex features encountered in application to practical airframe structures. Graphics from a computational model of a 2D physical demonstration system show the configuration and strain in the slat-cove filler in the deployed and stowed conditions. Features enabling stowage of a large curvilinear length (sliding hinge) and maintenance of the optimized outer mold line (auxiliary component) are highlighted. Other advancements for application to 3D, flight airframes are visible in the image from a model for one entire section of a slat-cove-filler treatment for a wide-body, transport-class aircraft. NASA Langley also offers a design for a deformable structure that is deployed from the leading edge of the main-wing element, termed the slat-gap filler. It closes and covers the gap between the slat and the main-wing element, but can be readily and autonomously opened in emergency to regain the baseline high-lift configuration and its corresponding lift performance at high angles of attack. This approach has similar benefits as the slat-cove filler device. NASA's Langley Research Center developed a deployable and stowable mechanical design for filling the cavity behind the leading-edge slat (i.e., slat cove), when it is extended upon landing approach of an aircraft. Aerodynamic flow over an unfilled cavity typically exhibits strongly unsteady behavior that is a source of aeroacoustic noise. Conventional leading-edge slat devices for high lift are a good example of such geometric and flow conditions and are a prominent source of airframe noise. Experimental and computational results have shown that a slat-cove filler device could significantly reduce the noise produced by slat structures without aerodynamic penalty. The proposed structural concept will enable autonomous achievement of the desired deployed shape. The design will facilitate a clean cruise configuration with minimal weight addition to the aircraft. NASA is seeking development partners and potential licensees.