Experimental and numerical investigation of fabric permeability on drag of conventional parachute

Drag is the principle criteria for parachute design. One of prevalent assumption in simulation of parachutes is simplifying the inflated parachutes by assuming that parachute's canopy is impermeable. In this research, the impact of this assumption in reducing the numerical simulation's accuracy was verified. Via applying the coefficients of Darcy's modified equation, resulted from the experiments carried out on canopy's fabric, the numerical simulation of a simplified canopy was performed. Regarding permeability and its effects on flow regime, accuracy in simulation increased and drag coefficient sank to 24% reduction in comparison with impermeable canopy.
In experimental test on both permeable and impermeable semi-spherical canopies in low-speed wind tunnel, drags in both cases were measured. Considering the geometry of inflated canopy in the wind tunnel test, numerical simulation was accomplished while regarding the canopy's permeability and results were compared to experimental test.
Comparison of the results of permeable and impermeable canopies including drag, pressure profiles and flow lines indicates the significance of observing permeability in parachute's numerical simulation.