The inflation process and safety analyses of a parachute ejected from civil aircrafts

The ejectable emergency flight data recorder equipped with a parachute show promising prospects in aircraft safety and rescue. However, compared to rigid objects, the flexible canopy of an ejected parachute during its inflation process is more likely to collide with the fuselage, which brings potential safety hazards. Therefore, the aerodynamic characteristics and trajectories of a parachute ejected from a civil aircraft are studied numerically by the Arbitrary Lagrange Euler method (ALE). The effects of the free-stream conditions, i.e., the velocity and angle of attack on the parachute inflation process, aerodynamic characteristics, and flow fields are analyzed. Results show that when the parachute is close to the fuselage, the shear layers and vortical motions around the canopy are modified by the fuselage. Nevertheless, the parachute does not fail completely. Meanwhile, the projected area and opening load of the canopy are relatively small. The critical angle of attack of at the free-stream with velocity bewteen 40 m/s and 160 m/s is obtained. The safety condition for ejections is given at last. This work provides a theoretical support for the design of ejectable flight data recording and emergency tracking systems.