Design definition and Test campaign

Engineering the reference mission/system use-case

During the re-entry, complex aerothermal phenomena occur around the body, and then Inflatable heatshields are exposed to extremely harsh conditions due to a rapid temperature rise and dissociation and possible ionization of gases across the bow shock.
Therefore, the investigation and development of the key technologies on board Inflatable Heat Shields (Flexible TPS and Inflatable Structure) must rely on a multi-disciplinary engineering effort to cover design definition tasks through
mission analysis and design, trajectory analyses, aerodynamics and aerothermodynamics analysis, system configuration and architecture definition, key sub-systems preliminary design and definition (Flexible TPS, Inflatable Structure).
During the second stage of the project, a design definition loop will be put in place following the steps. The loop will allow assessment and consolidation of the baseline mission scenario (ConOps) along with the system architecture that best fits the candidate use case identified with the business case analysis.
Afterwards, the aero shape and the system configuration (both functional and physical) will be defined through CAD and CFD tools. Then the CFD analysis will produce the basic aerodynamics data of the shape (aero-data set). Hence, trajectory analysis will be appointed with the identification of the mechanical and thermal environment the system has to cope with during its re-entry path.

The environment will feed in turn the preliminary sizing of the mechanical and thermal aspects of the systems strictly related to the two key technologies (i.e.: Flexible TPS and Inflatable Structure by elaboration of numerical models: Thermo-Mathematical-Model (TMM) for the F-TPS and structural model (FEM) for the IS.
Finally, the CFD and FEM models will be put in short-circuit to execute a loop of Fluid-Structure Interaction analysis (explained in more detail in the second part of this paragraph).
In parallel, morphing models will be realized and the flying quality of the vehicle will be assessed through a dedicated analysis.

Testing

Tests in representative environments are needed to increase the knowledge of the aerodynamic behaviour and the mechanical behaviour of the Inflatable Heat shields. This phase of the project will allow verifying by testing some of the important aspects related to the physics of the Inflatable Heat Shields that were not covered in the frame of the father project EFESTO.

Subsequently, the test results will be widely exploited to revisit numerical models and then improve their level of confidence through cross-correlation and rebuilding of tests.

The EFESTO-2 test campaign will focus on aerodynamics stability and mechanical characterization of the Inflatable Heat Shields with two parallel efforts:

• the Aerodynamics and Flying Qualities investigation, through cold-flow wind tunnel testing of sub-scaled models to investigate the critical phenomena of dynamic and static stability of capsule-like bodies with a focus on deformed shapes at meaningful flow regime;
• the IAD mechanical characterization, by ground testing the 1:2 scale demonstrator test-article produced within the EFESTO project, to further explore structural behaviour through modal survey, stiffness and deformation measurements, morphing observation and materials characterization;