Fluid-Structure Interaction Simulation of an Inflatable Aerodynamic Tension-Cone Decelerator

Abstract

Inflatable aerodynamic decelerators have potential advantages for planetary re-entry in robotic and human exploration missions. In this paper, we focus on an inflatable tension cone design that has potential advantages over other geometries. A computational fluid-structure interaction model of a tension cone is employed to investigate the behavior of the inflatable aeroshell at supersonic speeds for conditions matching recent experimental results. A parametric study is carried out to investigate the deflections of the tension cone as a function of inflation pressure of the torus at a Mach of 2.5. Comparison of the behavior of the structure, amplitude of deformations, and determined loads are reported. The design of light supersonic parachutes, inflatable decelerators and propulsion systems used in the entry-decent-landing (EDL) sequence of planetary exploration missions has advanced research into the development of sophisticated hybrid computational fluid dynamics (CFD) and finite element analysis (FEA) models. These computational models describe the fluid-structure interaction of systems with complex geometries [1]. Theoretical concept designs indicate that an inflatable aerodynamic decelerator (IAD) provides an alternative means to decelerate heavy payloads into the atmospheres of earth and other planets. These new concepts may be exempt from instabilities present in other decelerator methods within the Mach number range of interest, e.g. parachutes [2]. Preliminary experimental results from the 1960’s along with recent experiments [3] indicate that IADs may offer a superior advantage over supersonic parachutes for high-payload deceleration. They provide a larger drag area at higher Mach number, enabling increasing elevation landing sites along with reduced vibrations and oscillations during the entry process. In this paper, a state of the art CFD model based on structured and adaptive mesh refinement (AMR) is interfaced with a newly developed large deformation thin-shell/membrane solver to investigate the behavior of a tension cone inflatable aerodynamic decelerator in supersonic flow with varying inflation pressure. II.Computational Models and Approach A three-dimensional large-eddy simulation (LES) fluid model employing a conservative finitedifference method with low numerical dissipation is used. The solver is capable of simulating turbulence using LES and capturing strong shocks while optimizing computational efficiency by means of dynamic AMR [4]. This hybrid solver uses two different numerical schemes to deal with strong shocks and turbulence, respectively. In regions where shocks are present, the model employs a finite-difference weighted-essentially non-oscillatory (WENO) scheme to accommodate flow discontinuities. In the turbulent regions, a non-dissipative central-difference scheme (in stable skew-symmetry form) is used. In both cases, the finite-difference stencils are tuned to minimize dispersive errors at the interface of the two schemes. The finite-difference method used in the fluid model presents some computational advantages in the approximation of the numerical fluxes in the fluid mesh, i.e., less cost, when compared to a finite