Numerical and experimental investigation of damage effect on a hemispherical parachute performance

Abstract

The effect of the canopy fabric damage on parachute performance has been investigated numerically and experimentally in the present paper. For this aim, first, flow structure around the parachute canopy has been studied for both damaged and undamaged parachutes. Then, the drag coefficient as the main characteristic of a parachute performance has been examined and compared experimentally and numerically in four Reynolds numbers. Experimental tests for undamaged and damaged canopies have been carried out in an open-circuit wind tunnel laboratory at the velocities 15, 20, 25, and 30 m/s. In order to measure the drag force, a valid tensile load-cell has been used. Also, the smoke flow visualization has been utilized to find the flow behavior at different regions of the parachute. For the numerical simulation, an incompressible pressure-based CFD code using the finite volume method has been applied to solve the complex turbulent flow field around the inflated parachute canopy. To increase accuracy of the numerical simulation, the permeability boundary condition on the parachute canopy has been implemented and its effects have been considered on the flow field. The numerical results indicate that the permeability assumption on the canopy makes desirable results compatible with the experimental ones. Moreover, comparison of the results between damaged and undamaged canopies demonstrates significant differences in the streamlines, pressure distributions, and drag coefficients. As the reliability is the main criterion for the parachute system, investigation on the damage effects would be useful and it has been considered in the present work.