@MastersThesis{Torres:2017:AnAtEf,
author = "Torres, Luis Carlos Roldan",
title = "Angle of attack effect in the aerothermodynamics of a hypersonic
vehicle with a surface discontinuity of gap type",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2017",
address = "Cachoeira Paulista",
month = "2017-03-29",
keywords = "direct simulation Monte Carlo, escoamento hipers{\^o}nicos,
escoamento rarefeito, filete, ve{\'{\i}}culos hipers{\^o}nicos,
direct simulation Monte Carlo, hypersonic flow, rarefied flow, gap
flow, hypersonic vehicle.",
abstract = "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. RESUMO: O desenvolvimento de
ve{\'{\i}}culos hipers{\^o}nicos tem se tornado um tema de
interesse nos {\'u}ltimos anos, considerando-se a possibilidade
de se chegar com tais ve{\'{\i}}culos a locais at{\'e}
ent{\~a}o inacess{\'{\i}}veis como os voos orbitais. A
constru{\c{c}}{\~a}o desses ve{\'{\i}}culos exige materiais
especiais e deve apresentar uma forma aerodin{\^a}mica eficiente
para resistir altas velocidades al{\'e}m de temperaturas elevadas
e mudan{\c{c}}as de press{\~a}o significativas. O estudo
descrito nesta disserta{\c{c}}{\~a}o foi realizado com o
objetivo de investigar o impacto de descontinuidades presentes na
superf{\'{\i}}cie de ve{\'{\i}}culos espaciais
hipers{\^o}nicos. Em busca deste objetivo, simula{\c{c}}{\~o}es
computacionais de um escoamento hipers{\^o}nico rarefeito sobre
uma placa plana, foi realizada usando-se o m{\'e}todo Direct
Simulation Monte Carlo. As simula{\c{c}}{\~o}es forneceram
informa{\c{c}}{\~o}es sobre a natureza da estrutura do
escoamento, propriedades primarias e propriedades
aerodin{\^a}micas, devido a varia{\c{c}}{\~o}es na raz{\~a}o
comprimento-profundidade (L/H), e varia{\c{c}}{\~o}es no
{\^a}ngulo de ataque. Uma descri{\c{c}}{\~a}o das propriedades
primarias, tais como velocidade, massa espec{\'{\i}}fica,
press{\~a}o e temperatura, e das quantidades aerodin{\^a}mica,
tais como transfer{\^e}ncia de calor, press{\~a}o e atrito na
superf{\'{\i}}cie, foi obtida por um m{\'e}todo num{\'e}rico
que leva em conta os efeitos de n{\~a}o-equil{\'{\i}}brio no
regime de transi{\c{c}}{\~a}o. Os resultados para um filete
definido por uma raz{\~a}o L/H de 1, 1/2, 1/3 e 1/4, e com
{\^a}ngulo de ataque do escoamento de 10, 15 e 20 graus, foram
comparados com os de uma placa plana sem a presen{\c{c}}a de um
filete. A an{\'a}lise mostrou que a estrutura do escoamento
dentro do filete com {\^a}ngulo de ataque {\'e} ligeiramente
diferente daquela com zero grau de incid{\^e}ncia para cada
raz{\~a}o L/H investigada. Verificou-se que os valores
m{\'a}ximos para os coeficientes de transfer{\^e}ncia de calor,
press{\~a}o e coeficiente de atrito ocorreram na
superf{\'{\i}}cie a montante do escoamento dentro do filete.
Verificou-se tamb{\'e}m que, os valores m{\'a}ximos para o
coeficiente de transfer{\^e}ncia de calor dentro do filete
aumentaram com o aumento do {\^a}ngulo de ataque \$\alpha\$.
Como resultado, em termos de press{\~a}o, a presen{\c{c}}a do
filete sobre a superf{\'{\i}}cie do ve{\'{\i}}culo n{\~a}o
pode ser ignorada no projeto do ve{\'{\i}}culo.",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)}",
committee = "Santos, Wilson Fernando Nogueira dos (presidente/orientador) and
Kalempa, Denize and Leite, Paulo Henrique Mineiro",
englishtitle = "Efeito do {\^a}ngulo de ataque na aerotermodin{\^a}mica de um
ve{\'{\i}}culo hipers{\^o}nico com descontinuidade na
superf{\'{\i}}cie do tipo filete.",
language = "en",
pages = "185",
ibi = "8JMKD3MGP3W34P/3NU8MJS",
url = "http://urlib.net/ibi/8JMKD3MGP3W34P/3NU8MJS",
targetfile = "publicacao.pdf",
urlaccessdate = "27 abr. 2024"
}