Computation of Flow over a High Performance Parafoil

The steady, incompressible Navier-Stokes equations along with the one equation Spalart-Allmaras turbulence model were solved using a finite-volume flow solver to examine the flow field and forces on the central cross-section of a high performance parafoil. The parafoil surfaces were assumed to be impermeable, rigid and smooth. The parafoil flow field consists of a vortex just inside of the cell opening which effectively closes off the cell and diverts the flow around the leading edge. The flow about the parafoil experiences a rather bluff leading edge in contrast to the smooth leading of the baseline airfoil. The flow pattern also creates a separation bubble on the lower leading edge of the parafoil. The lift of the parafoil section increases linearly with the angle of attack up to 8.5 and the parafoil lift curve slope is about 8 % smaller than the same for the baseline airfoil. The cell opening has a major effect on the drag prior to stall; the parafoil drag is at least twice the baseline airfoil drag. The minimum drag of the parafoil section occurs over the angle of attack range of 2.5 – 7. I