Computational Validation, Verification, and Stability Analysis of Ring-slot and Flat Circular Parachutes

This paper describes a computational aerodynamics study of the drag and stability characteristics of rigid extraction parachute models. Computational fluid dynamics (CFD) simulations were conducted for both a 20% geometric porosity ring-slot canopy (20P RS) and 0% geometric porosity canopy (0P RS) in freestream conditions. The primary purpose of these simulations was to verify and validate simulations with the 20P RS and 0P RS canopies, thus creating increased confidence in the accuracy of extraction parachute CFD for future implementations as a part of the analysis for the Heavy Equipment Large Low Velocity AirDrop System (HELLVADS). Variation in Newton sub-iterations between three and five was conducted to determine the effect on temporal accuracy for verification of parachute aerodynamics with theoretical expectations. Validation of these CFD simulations was carried out through comparison of computational results to that of experimental results for similar rigid parachute models. Simulations predicted that the minimum number of Newton sub-iterations required for verification was five. Validation of drag coefficient for the 20P RS canopy was achieved, along with verification of lift and pitching moment coefficients at zero and five degrees angle of attack (AoA). Validation of drag coefficient for the 0P RS canopy was also achieved at 0°AoA, and verification data was also collected.