Estimation of Incompressible Swept-Wing Aerodynamics Using Low-Fidelity Methods

摘要

Sweep is often used for both subsonic and supersonic aircraft design. In low-speed applications, sweep is sometimes used to maintain longitudinal trim and stability on a flying-wing design. While high-fidelity computational simulations and experimental approaches can provide accurate estimations of lift, drag and pitching moment, the computational expense can become too high when exploring a large design space. A major advantage of analytic solutions and low-fidelity methods is that they can quickly analyze hundreds of wing designs of varying planform and sweep angles to provide a clear relation between design variables and performance characteristics. This paper considers the effects of sweep on lift, induced drag and aerodynamic center location over a large range of wing planforms and sweep angles. Aerodynamic predictions from the analytic classic lifting-line theory are compared to three computational methods. The computational methods include a modern numerical lifting-line algorithm, a vortex-lattice method and a high-order panel method. For wings without sweep, all analytic and numerical methods are used to calculate correction factors to estimate the penalty on induced drag and lift slope due to taper as compared to a wing with an elliptical lift distribution. Results from all three numerical methods are used to evaluate sweep-correction factors relative to solutions without sweep. Results from each method are compared and conclusions are drawn about the accuracy of the various methods. These sweep-correction factors can be applied to analytic or numerical results for wings without sweep to estimate lift, induced drag and aerodynamic center location if that wing planform were to be swept back.