Computational Investigation of Effects of Leading and Trailing Edge Deflections on VR-12 Airfoil Aerodynamic Characteristics

Abstract

A computational study of the effects of leading and trailing edge deflections on a Boeing VR-12 airfoil is conducted along with the experimental investigation of Refling et al. [1] in order to identify optimum shape changes that will provide improved aerodynamics characteristics under the broad range flow conditions experienced in rotorcraft applications. This is in preparation of producing a shape morphing airfoil that can cycle through these different optimized shapes to maintain better performance in various flow conditions. Initial evaluation of shape modifications are performed using XFLR5 software for the Boeing VR-12. A pair of LE and TE deflection angles are selected for experimental and further computational investigations. Computations are performed using ANSYS CFX utilizing SST turbulence model coupled with γ-〖Re〗_(θ )transition model. The numerical simulations are used for the optimization of the morphing airfoil design and their development is parallel to the experimental methods [1] that use Particle Image Velocimetry and Pressure Sensitive Paints. The experimental methods are performed in a wind tunnel where boundary conditions including walls, blockage, free stream uniformity and turbulence levels need be taken into account in the simulations. While characterization of these wind tunnel conditions is assessed for matching with the simulation conditions, initially there are some expected discrepancies in flow separation locations and extent seen between experimental and computational data, that is believed to be caused by wind tunnel free-stream and boundary conditions mismatch with the simulation conditions that determine the proper boundary and turbulence/transition modeling. Detailed measurements are being conducted in the test section to provide more accurate turbulent quantities for computations. Current results for the morphing optimization using lift and drag coefficient comparisons are presented along with velocity and pressure fields for selected morphing shapes at various angles of attack.