The parachute deceleration has an irreplaceable role in aeronautic and astronautic engineering. Its typical applications are in spacecraft recovery, fighter plane pilots for lifesaving, aircraft landing and airdrop. Compared with experiments, numerical simulations can offer significant advantages of expense and turn-around time for parachute design and analysis.During the deployment and subsequent inflation, parachute fabric materials can undergo large and arbitrary deformation in a very short time with sustaining a small stress and strain. such kind of thin and flexible membrane–rope structure poses unavoidable challenges for all of computational structure dynamics (CSD), computational fluid dynamics (CFD) and computational mesh dynamics (CMD).Due to inherent poor accuracy of empirical techniques some computational methods have been developed to predict the dynamic deployment and subsequent inflation. At the early stage the flow around parachute is often treated as incompressible, pressure-based approaches are used for CFD, CMD approaches include spring-analog method, solid elasticity analog method, immersed boundary method and the front tracking method. Recently numerical simulations were conducted on some practical parachute configurations, in which the finite element method was employed to solve both the structure and fluid dynamic leading to the space–time fluid structure interaction (FSI) technique. On the other hand, commercial software LS-DYNA provided some new features to simulate parachute deployment and subsequent inflation, which is based on the coupled &nbsp;arbitrary Lagrangian-Eulerian (ALE) method and penalty algorithm.&nbsp;In this paper, a new numerical FSI simulation technique is proposed and developed to simulate a highly folded parachute configuration by combining the advantages of the nonlinear finite element method and the preconditioning finite volume method. Applying an incompressible fluid solver to study parachute FSI problems has been investigated by many researchers, but the application of a density-based method has been poorly investigated, and the combination of an implicit structure algorithm and an implicit fluid scheme also needs to be developed. Based on these purposes, the code is consisted of three independent modules which are designed to solve the unique problem according to their own strengths. The first module is CSD and an implicit nonlinear structural dynamic module which is based on membrane–rope elements. Different from commercial software, a tangent stiffness matrix for fabric materials has been introduced and derived in detail to formulate the nonlinear implicit structural dynamic equations, and the Newton–Raphson iteration algorithm has also been implemented to solve these nonlinear implicit equations during each physical time step. Moreover, a wrinkling detection and processing algorithm has been developed to improve the performance of membrane elements and ensure the dynamic stability during the unfolding stage. The second module is CMD and a robust mesh-moving function which works as a bridge between the structure and the fluid module. The pseudo solid algorithm has been used to update the fluid mesh at each time level during FSI simulation. The last module is a CFD solver which is based on the preconditioned Reynolds averaged Navier–Stokes (RANS) equation. The unstructured lower–upper symmetric Gauss–Seidel (LU-SGS) scheme is employed in this finite volume solver to accelerate the solution convergence and make the better coupling with the implicit structure solver.&nbsp;In this work the C-9 parachute and slot-parachute (S-P) were simulated to validate the proposed FSI method. There are four stages in the FSI simulation: the first is the deployment phase, the second is the pre-inflation phase which is designed to simulate the parachute unfolding procedure; the third is the system breath vibration phase aiming at locating the dynamic equilibrium position; the last is the FSI simulation of the parachute terminal descent stage when parachute system tends to be stable. The computed results for both parachutes have demonstrated the proposed FSI method to be a useful tool for analyzing dynamic parachute deployment and subsequent inflation.&nbsp;&nbsp;

Fluid-Structure Interaction Simulations of Parachute Deployment and Inflation

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.