Effects of protuberances on surface loads on the Vega-C launch vehicle

The need to meet the demands of the aerospace market in terms of payload capability, mission flexibility, and cost reduction has led the European Space Agency to develop Vega-C as an evolution of the original Vega launcher. The design of a modern launch vehicle like the Vega-C requires accurate evaluation of the thermal and mechanical loads on its surface under conditions as close as possible to real flight conditions. Despite its apparently simple aeroshape, the Vega-C surface is characterized by the presence of antennas, wiring ducts, flanges, and retrorockets. These protuberances interact with the external supersonic stream during the launcher's flight, giving rise to locally complex flows that can impose stresses on the launcher structure through the generation of severe mechanical and thermal loads. The present work focuses on an in-depth aerothermal analysis of Vega-C protuberances under specific flight conditions. Numerical computations are carried out using the commercial solver CFD++ on multiblock structured Chimera grids to assess which protuberances are subject to the most severe surface loads. Particular emphasis is placed on the role of boundary-layer thickness in the heat flux and pressure peaks that occur on the protuberances.