Computation of Flow over a High-Performance Parafoil Canopy

摘要

The incompressible Navier–Stokes equations together with the one equation Spalart–Allmaras turbulence modelnwere solved using a finite volume flowsolver to examine the flowfield and forces on the central cross section of a high-nperformance parafoil canopy. The parafoil surfaces were assumed to be impermeable, rigid, and smooth. Thenflowfield consists of a vortex inside the parafoil cell opening, which effectively closes off the opening and diverts thenflow around the leading edge. The flow about the parafoil experiences a rather bluff leading edge, in contrast tonthe smooth leading of the baseline airfoil. A separation bubble exists on the lip of the parafoil lower surface. The liftncoefficient of the parafoil section increases linearly with the angle of attack up to 8.5 degrees and the parafoilnlift-curve slope is about 8%smaller than the same for the baseline airfoil. The cell opening has a major effect on thendrag before stall; the parafoil drag is at least twice the baseline airfoil drag. Theminimumdrag of the parafoil sectionnoccurs over the angle-of-attack range of 2.5–7 degrees.