The parachute is widely used in aerospace engineering due to its high performance as a kind of &nbsp;&nbsp;decelerator dragged by aerodynamic forces. The aerodynamic forces acting on the parachute suspension lines and uninflated canopy during the parachute deployment play a key role in the parachute pre-inflation/inflation &nbsp;behavior. The parachute deployment is the first step for parachute to begin decelerating. As one of design conditions the deploy direction should be parallel to the wind direction. In case the deployment direction is not aligned with the relative wind, the phenomenon of line sail can be observed, the line sail gets its name from resemblance of the line curvature to that of sail. In this case the lines and canopy tend to move away from the vehicle faster than the bag and exit the bag from the side or the back. Once the line sail appears there is a tendency for bull whipping, false venting or unsymmetrical inflation to cause high localized stresses in the canopy. These characteristics are undesirable and should be minimized or at least well understood. Moreover, the line sail would result in significant changes in the time sequence to bag strip and therefore the ability to predict conditions at parachute inflation. The entry vehicle attitude is influenced by the direction of the inelastic line load during this time period, and therefore its rate response to the parachute opening load is significantly altered.&nbsp;A numerical model is developed to study the effects of aerodynamics on line sail during the bag stripping process. The model consists of breaking the suspension lines and canopy into several point masses, each acted upon by the aerodynamic drag of a line segment. The point masses are elastically coupled in chain-like fashion between the deployment bag and the vehicle, both of which are modeled in 6 degree-of-freedom. By tracking the line masses relative to the vehicle, the extent of line sail at any time can be presented to check its progress. In addition, the direction of inelastic line loads is accounted for in both vehicle and bag dynamics. The model is helpful in exposing system problems early in the development phase and therefore contributes to minimizing parachute development costs.&nbsp;This work is to numerically simulate the dynamic parachute deploying process. As the result, the effects of aerodynamics on line sail during the process are investigated. Several key parameters are considered such as parachute ejection velocity, angle of attack of spacecraft, Mach number and air density.

Effects of Aerodynamics on Line Sail During Parachute Deployment

Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2021/volume/85284

ASME 2021 Fluids Engineering Division Summer Meeting (FEDSM2021)

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.