This work presents an integrated workflow for preliminary aerodynamic design and multi-objective optimization of non-winged reentry vehicles, namely bicones, cones, and capsules. The focus of the work is on the hypersonic regime, but the purely supersonic regime is also included. Geometries were systematically parameterized—including with Class-Shape Transformation (CST) method—to define a design space that is both tractable and capable of representing relevant features. Deep neural networks were trained as surrogate models to deliver fast predictions of aerodynamic coefficients, heat flux, and volumetric metrics for sampled configurations. Training databases were generated: low-fidelity data was obtained using the Modified Newtonian local inclination method and high-fidelity data was obtained from Computational Fluid Dynamics (CFD) simulations. For bicones, a multi-fidelity strategy was employed, combining scarce and expensive high-fidelity data with abundant low-fidelity data to preserve accuracy while covering a wide region of the design space at low cost. Once validated, the surrogate models were coupled with a multi-objective genetic algorithm, Non-dominated Sorting Genetic Algorithm II (NSGA-II), to perform Aerodynamic Shape Optimization (ASO) under different flight conditions. The objectives were to maximize the lift-to-drag ratio and the vehicle volume while minimizing a heat flux parameter. The resulting Pareto fronts showed clear and physically interpretable trade-offs and produced vehicle geometries consistent with hypersonic aerodynamic theory. Furthermore, the low prediction errors relative to both low- and high-fidelity references confirm the robustness of the surrogate models.
Transpiration cooling is a very promising active method for thermal management of critical components for hypersonic flight. On the other side, its efficiency is affected by the characteristic of the cooling gas outflow from the porous material. This paper presents a study on the outflow characteristics of a sharp-edged, transpiration cooled fin as flown as part of the FinEx experiment of the HIFLIER1 sounding rocket. The permeable ceramic matrix composite material used for the transpiration cooled leading edge shows in general a outflow pattern dominated by single jets, distributed relatively homogeneous over the surface, disrupted by significant strong jets induced by small inhomogeneities. The general strongly anisotropic outflow characteristics were also investigated. The findings of the outflow characterization led to valuable insights for the design of future sharp-edged transpiration cooled structures.
The coupled numerical fluid flight mechanics and structure simulation (CoNF ^2 aS ^2 ) tool is a DLR-developed coupling environment specifically designed for spacecraft applications. As the name already implies, the focus of CoNF ^2 aS ^2 lies in the interactions between fluid, thermal, structural, and flight mechanics for aerodynamic and aerothermal load calculations. Like any numerical tool, the continuous upgrade of CoNF ^2 aS ^2 through wind tunnel experiments and flight tests is an ongoing process with a permanent expansion of its application possibilities. The main goal of CoNF ^2 aS ^2 is to achieve realistic simulations of space transportation vehicles in their entire flight range. This paper presents validation examples as well as an overview of the current development status of CoNF ^2 aS ^2. Some of the possible fidelity levels of CoNF ^2 aS ^2 are introduced and accompanied by example applications.
The effect of VUV irradiation on polyphenyl-methylsiloxane (PPMS)-coated quartz substrates was investigated by simultaneous in situ measurements of transmittance spectra and sample images. Although unirradiated PPMS was highly transparent, the transmittance of both the thick and thin films initially decreased and then partially recovered during irradiation. The simultaneous in situ observations showed that the initial decrease in transmittance originated mainly from enhanced light scattering rather than visible coloration, as the irradiated region became cloudy without a noticeable color change. The subsequent recovery was attributed to a reduction in scattering, although the recovery process differed between the thick and thin films. Quartz crystal microbalance measurements indicated that mass loss occurred only during the initial stage of irradiation, while X-ray photoelectron spectroscopy suggested the formation of silica-like SiO _x species in the near-surface region after irradiation. These findings demonstrate that simultaneous in situ transmittance and imaging measurements are an effective approach for identifying the mechanisms responsible for both transmittance degradation and recovery in VUV-irradiated silicone contamination films.
In aerospace engineering, electronic equipment is always connected to the cabin via connection brackets, which often exhibit a notable amplifying effect on the vibration signals transmitted from the cabin. To guarantee the normal operation of electronic equipment, it is essential to investigate the vibration and shock response of these connection brackets in the harsh environment of aerospace engineering. Currently, the most commonly used connection brackets are fabricated using aluminum alloy through the sheet metal process. This paper compares the random vibration and shock response of the connected brackets made of different materials through both experimental and numerical methods, and further investigates the effects of different structural configurations on their dynamic responses. The objective is to mitigate the vibration response of the connection brackets in high-frequency random vibration environments and high-magnitude impact environments. Experimental results indicate that brackets fabricated with sandwich materials exhibited the lowest response measured in both random and shock vibration environments. Additionally, numerical results show that the box-shaped structural form obtained the lowest measured vibration response. This provides new insights and data to support the optimization and design of connection brackets for electronic equipment in aerospace engineering.
