Numerical study on ring slot parachute finite mass inflation process and wake recontact phenomenon

To study the parachute finite mass inflation process and the wake recontact phenomenon, the Arbitrary Lagrangian-Euler coupling method is used to analyze the two sets of parachute-load systems with M_r=0.95, F_r=298 and M_r=1.77, F_r=144. The comparison between the numerical simulation results and the airdrop experiment results shows that this method can simulate the parachute finite mass opening process and the wake recontact phenomenon successfully. In parachute-load systems with and without wake recontact phenomenon, the opening force, aerodynamic coefficient, flexible canopy deformation, and surrounding flow field structure are analyzed. The results reveal that in the parachute-load system where the wake recontact phenomenon does not occur, there exist small outward jets at the canopy vent and gap. The outward jets push the canopy wake away from the canopy surface. The parachute maintains a fully inflated shape, and the drag is relatively stable. Conversely, considering the system where wake recontact occurs no outward jets were observed at the canopy vent and gap. The wake region behind canopy always follows the parachute-load movement. At a certain time, the wake region begins to catch up with canopy surface and this phenomenon leads to parachute apex collapsing and serious drag coefficient loss. As the parachute-load system deflects, the wake is dissipated and gradually moves away from the canopy, and the parachute is then reinflated and reaches the stable landing state.