Session: SYMP 4-3: Adaptive Aerospace Systems

Paper Number: 140934

140934 - Design and Fluid-Structural Analysis of a Shape Memory Alloy-Based Model-Scale Slat Gap Filler for Airframe Noise Reduction 

Airframes create significant acoustic noise during aircraft takeoff and landing. High-lift devices, such as slats and flaps, are a key contributor to airframe noise. With the forward slat deployed, geometric gaps cause the airflow to recirculate under the slat. Unsteady flow accelerating through the gap between the slat trailing edge and the main wing leading edge contributes to the recirculation region. This recirculation region is the primary source of noise for a slat. Higher-pressure air beneath the wing flows toward the lower-pressure region above the wing, creating an additional vortex at the slat trailing edge. Shape memory alloy (SMA) slat gap fillers (SGF) significantly reduce radiated noise by preventing the flow from traveling through the slat gap, which also eliminates the recirculation region as the slat trailing edge vortex dissipates and mitigates recirculation, thus reducing acoustic noise. Previous research performed by Texas A&M and NASA explored different SGF concepts and their effects on radiated noise and aerodynamic performance. These designs had a slightly lower maximum lift coefficient and a decreased stall angle of attack but maintained the required lift for normal operations. The SGF aerodynamic performance necessitated a requirement that it must reopen the slat gap to restore lift in an emergency case. This requirement, along with the standard operational needs of the slat (i.e., deployment and retraction) to enable an articulated wing, constrains the geometry design space. The SGF geometry in this work was determined from a multi-objective structural optimization using static loading conditions. However, the fluid-structure interaction (FSI) behavior of the proposed SGF configuration has not yet been established. Analysis of the modeled SGF design is implemented on a 1/16th scale NASA Common Research Model (CRM) articulated infinite 2-D extrusion wing through coupled fluid-structural analysis using Abaqus and Star CCM+. The FSI coupling allows bidirectional information exchange between the structural and fluid domains to obtain an accurate solution for structural deformation and flow field information. FSI allows for a more in-depth exploration of the structural and aerodynamic behavior of the SGF. In this work, we study the FSI behavior of the SMA-based SGF as it performs under different loading conditions including the nominal operation and emergency retraction cases. The nominal operation case represents the SGF experiencing typical takeoff and landing loads. In contrast, the emergency retraction case is a dynamic load case where the SGF retracts back to the main wing and conforms to the outer mold line of the main wing. Results include a study of the expected structural performance of the SGF and system aerodynamic and vibrational performance under varying aerodynamic conditions, which will inform future design.

Presenting Author: Liam Mccue Texas A&M University

Presenting Author Biography: Liam McCue is a graduate student in the Department of Aerospace Engineering at Texas A&M University. Liam graduated from the University of Maryland College Park with a Bachelor of Science in Aerospace Engineering and a minor in Business. He was involved with the Collective Dynamics and Control Laboratory (CDCL) at UMD under Dr. Derek Paley working on actuators for electric micro-mobility. Liam has also worked at NAWCAD as a propulsion and subsystems flight test engineering intern for rotorcraft platforms. Liam currently supports the NASA Slat Gap Filler project which aims to study morphing aerostructures for noise reduction. His work focuses on designing and building a NASA CRM wing with shapeset SMA for wind tunnel experimentation.

Authors:

Liam Mccue
Kevin Lieb
Darren Hartl