Aerodynamic Analysis of Large Aspect Ratio Parafoil

Abstract

Large aspect ratio parafoils are more attractive compared with moderate ones less than 3.5, since they either improves load-carrying capacity with the same aero-dynamical area or decreases taxing speed with the same load. Based on its original airfoil, one open-source elliptical parafoil with 4.7 AR is modified while scaling the canopy geometric parameters, then CFD simulations, solving the incompressible Reynolds time-averaged Navier-Stokes equation with the (SST) K-ω turbulence model in the finite volume method, are adopted to analyze its aerodynamics in forward taxing mode as well as steering mode with lateral wind. With the numerical simulation results of this canopy, lift and drag are analyzed according to their attack angle profiles for taxing. The steering mode with the deflection of one-side flap increases the drag coefficient significantly, even it raises its lift simultaneously, reduces the lift-drag ratio, and generate rolling and yaw moments; The rolling moment due to lateral wind during steering mode has two phases of rising linked by a short straight line when sideslip angle increases, while yaw moment increases to a peak value then reduces, finally followed by a relatively stable trend. Compared with the above two moments, the pitching moment changes moderately with the increase of the sideslip angle, although it has an overall decreasing trend; The simulation of the modified canopy provides a calculation basis for its following manufacture and dynamical modelling.