Angle of attack effect in the aerothermodynamics of a hypersonic vehicle with a surface discontinuity of gap type

• Ano de defesa: 2017
• Autor(a) principal: Luis Carlos Roldan Torres
• Orientador(a): Wilson Fernando Nogueira dos Santos
• Banca de defesa: Denize Kalempa, Paulo Henrique Mineiro Leite
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Instituto Nacional de Pesquisas Espaciais (INPE)
• Programa de Pós-Graduação: Programa de Pós-Graduação do INPE em Combustão e Propulsão
• País: BR
• Link de acesso: http://urlib.net/sid.inpe.br/mtc-m21b/2017/05.23.23.55

The development of hypersonic vehicles has become a topic of interest in recent years, since has made it possible to reach inaccessible places such as orbital flights. The construction of these vehicles must be made with specials materials, and must have an efficient aerodynamic shape to withstand high speeds, high temperatures and significant pressure changes. The study described in this dissertation was undertaken with the objective to investigate the impact of discontinuities present on the surface of hypersonic space vehicles. In pursuit of this goal, computational simulations of a low-density hypersonic flow over a flat plate with a gap has been performed by using the Direct Simulation Monte Carlo method. The simulations provided information about the nature of the flowfield structure and the aerodynamic surface properties on the gap resulting from variations in the length-to-depth (L/H) ratio and variations in the angle of attack. A description of the flowfield properties, such as velocity, density, pressure and temperature, and aerodynamics surface quantities, such as, number flux, heat transfer, pressure and skin friction, were obtained by a numerical method that properly account for non-equilibrium effects in the transition flow regime. Results for a gap defined by L/H ratio of 1, 1/2, 1/3 and 1/4, and flow with angle of attack of 10, 15 and 20 degrees, were compared to those of a flat plate without a gap with zero-degree angle of incidence. The analysis showed that the flow topology inside the gap with incidence is slightly different from that for zero-degree angle of incidence for the L/H ratio investigated. It was found that the maximum values for the heat transfer, pressure and skin friction coefficients inside the gap took place on the gap forward face. It was also found that, maximum values for heat transfer coefficient inside the gaps increased with increasing the angle of attack $\alpha$. Nevertheless, it was observed that these maximum values are smaller than those observed in a flat-plate without a gap for the corresponding angle of attack. As a result, in terms of pressure, the presence of the gap on the vehicle surface can not be ignored in the vehicle design.