This paper presents selected results from an ongoing effort to develop an aerodynamic database from Reynolds-Averaged Navier-Stokes (RANS) computational analysis of airfoils and wings at stall and post-stall angles of attack. The data obtained from this effort will be used for validation and refinement of a low-order post-stall prediction method developed at NCSU, and to fill existing gaps in high angle of attack data in the literature. Such data could have potential applications in post-stall flight dynamics, helicopter aerodynamics and wind turbine aerodynamics. An overview of the NASA TetrUSS CFD package used for the RANS computational approach is presented. Detailed results for three airfoils are presented to compare their stall and post-stall behavior. The results for finite wings at stall and post-stall conditions focus on the effects of taper-ratio and sweep angle, with particular attention to whether the sectional flows can be approximated using two-dimensional flow over a stalled airfoil. While this approximation seems reasonable for unswept wings even at post-stall conditions, significant spanwise flow on stalled swept wings preclude the use of two-dimensional data to model sectional flows on swept wings. Thus, further effort is needed in low-order aerodynamic modeling of swept wings at stalled conditions.
A recently developed post-stall aerodynamics prediction method has been improved for use in real-time simulation of aircraft flight dynamics. The aerodynamic prediction method models the boundary layer separation due to stall using an effective decambering on each wing section. The aerodynamics of the configuration is rapidly calculated using superposition of stored lift distributions, which allows the the method to be used in real-time flight simulation even for post-stall conditions. For a given aircraft state vector, the method predicts forces and moments on the configuration. This aerodynamics method is coupled with flight-dynamics equations of motion (EOM) such that the complete aerodynamics is solved at each time step of the solution of the flight EOM. At the current stage, the approach does not handle the effects of bodies, propeller-wash, and wake interference. These are to be incorporated in follow-on work.
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