Work

Aerodynamic numerical reconstruction of experimental wind tunnel tests of an optimized inflatable heat shield in undeformed and deformed configurations for upper-stage recovery within the EFESTO-2 project

Year: 2026

Type: article

Abstract: Inflatable heat shields (IHS) represent a promising solution for atmospheric entry and recovery missions, enabling large aerodynamic area without being constrained by the diameter of launcher fairings. Within the EFESTO-2 project, an optimized inflatable heat shield has been investigated for the recovery of upper-stage launch vehicle components. This work presents a combined numerical and experimental study aimed at characterizing the aerodynamic behavior of such a system and validating numerical results. First, fluid–structure interaction (FSI) simulations were performed at several representative flight points along the reference re-entry trajectory to estimate deformation of the inflatable structure under aerodynamic loads. Representative deformed geometries were obtained using a weakly coupled CFD-FEM methodology, and one of them was used to define the configuration investigated experimentally. Wind tunnel campaigns were conducted in the DLR TMK and H2K facilities over a Mach number range from 1.4 to 7, providing measurements of static aerodynamic coefficients and dynamic stability characteristics. High-fidelity CFD simulations were then carried out to numerically reconstruct the experimental conditions and allow a detailed comparison with wind tunnel data. The results show good agreement between numerical predictions and measurements across the investigated Mach range. Structural deformation is found to have a limited impact on global aerodynamic coefficients but significantly modifies local heat-flux distributions. The combined experimental–numerical approach enables the establishment of a consolidated aerodynamic database and provides key insights into the stability and flight quality of inflatable re-entry systems intended for upper-stage recovery.

Source: Acta Astronautica

DOI: 10.1016/j.actaastro.2026.07.017