@MastersThesis{Roballo:2007:EsEsAt,
author = "Roballo, Suelen Trindade",
title = "Estudo do escoamento atmosf{\'e}rico no Centro de
Lan{\c{c}}amento de Alc{\^a}ntara (CLA) atrav{\'e}s de medidas
de torre anemom{\'e}trica e em t{\'u}nel de vento",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2007",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2007-04-02",
keywords = "meteorologia, penhasco, n{\'u}mero de Reynolds, anem{\^o}metro
de fio quente, rugosidade superficial, t{\'u}nel de vento,
atmosfera neutra, meteorology, cliff, Reynolds number, hot wire
ane.",
abstract = "Estudou-se o escoamento atmosf{\'e}rico no Centro de
Lan{\c{c}}amento de Alc{\^a}ntara(CLA), localizado junto a uma
fal{\'e}sia de 50 m de altura, (i) analisando dados de vento
coletados, nos per{\'{\i}}odos 1995 - 1999 (anos base) e 2004 -
2005 (para valida{\c{c}}{\~a}o), em seis n{\'{\i}}veis de
torre anemom{\'e}trica (TA) de 70 m, situada 200 m a jusante da
fal{\'e}sia, pr{\'o}ximo {\`a} rampa de lan{\c{c}}amento de
foguetes e (ii) simula{\c{c}}{\~o}es em t{\'u}nel de vento
(TV), na escala geom{\'e}trica 1:1000, com a
realiza{\c{c}}{\~a}o de quatro s{\'e}ries de ensaios, incluindo
configura{\c{c}}{\~o}es do piso, representando a fal{\'e}sia.
As observa{\c{c}}{\~o}es na TA, mostraram que a velocidade de
atrito u* foi igual a 0,32 ± 0,13 m/s (per{\'{\i}}odo chuvoso) e
0,46 ± 0,11 m/s (seco); o comprimento de rugosidade z0 foi igual a
0,19 ± 0,32 (chuvoso) e 0,06 ± 0,05 m (seco), demonstrando a
sazonalidade do perfil do vento. O expoente \α da lei de
pot{\^e}ncia para a velocidade variou de 0,19 a 0,27, ao longo
dos meses do ano, com R2s entre 0,88 e 0,99, e a decrescendo com a
altura zn. A valida{\c{c}}{\~a}o de \α com dados de vento
de 2004 a 2005 mostrou, em m{\^e}s chuvoso, velocidades locais
estimadas maiores que as observadas, talvez devido a neutralidade
atmosf{\'e}rica menos forte; entretanto, em m{\^e}s seco, elas
foram equivalentes, demonstrando condi{\c{c}}{\~o}es neutras da
atmosfera. Finalmente, a dire{\c{c}}{\~a}o do vento predominante
foi de Nordeste, seguida das de Norte e de Leste. Os ensaios no
TV, com degraus de 90° e de 70°, correspondentes {\`a}
fal{\'e}sia, ambos sem e com emula{\c{c}}{\~a}o de rugosidade
adicional a jusante deles, mostraram: (i) a perfeita
emula{\c{c}}{\~a}o do perfil de vento oce{\^a}nico (\α =
0,15) sobre a posi{\c{c}}{\~a}o do degrau representativo da
fal{\'e}sia, utilizando pista de tapete, a montante, para prover
a rugosidade necess{\'a}ria; (ii) que o n{\'u}mero de Reynolds
m{\'a}ximo poss{\'{\i}}vel com comprimento
caracter{\'{\i}}stico igual {\`a} altura do degrau neste TV foi
6,52.104, enquanto no CLA foi da ordem de 3.107, raz{\~a}o pela
qual {\'e} necess{\'a}rio um t{\'u}nel mais potente para emular
esta; (iii) que os \α mais pr{\'o}ximos dos observados
foram obtidos com um degrau reto, sem nenhum revestimento especial
no piso normal do t{\'u}nel, exceto o tapete a montante do
degrau; (iv) que a fixa{\c{c}}{\~a}o de cubos a jusante do
degrau resulta em rugosidades bem maiores que as observadas sobre
a vegeta{\c{c}}{\~a}o do CLA, possivelmente emulando
situa{\c{c}}{\~o}es urbanas ou industriais; (v) que
caracter{\'{\i}}sticas t{\'{\i}}picas do escoamento ap{\'o}s
o degrau, tais como o descolamento, a forma{\c{c}}{\~a}o de
bolha de circula{\c{c}}{\~a}o e nova ader{\^e}ncia foram
emuladas; (vi) que o uso de TVs mais potentes certamente
permitir{\'a} a emula{\c{c}}{\~a}o da situa{\c{c}}{\~a}o
atmosf{\'e}rica do CLA. Finalmente, com a utiliza{\c{c}}{\~a}o
de um TV mais potente, al{\'e}m da replica{\c{c}}{\~a}o dos
ensaios deste trabalho, testes com ventos incidindo em
{\^a}ngulos n{\~a}o retos no degrau s{\~a}o recomendados.
ABSTRACT: The atmospheric flow at the Alcantara Launching Center
(CLA), which is localized near a 50 m cliff, was studied through
(i) the analysis of wind data that were measured during the
periods from 1995 to 1999 (base years) and from 2004 to 2005 (for
validation), at six levels of a 70 m anemometric tower (TA), which
is placed 200 m downwind of the cliff, near a rocket launching
pad, and (ii) wind tunnel (TV) experiments, using a 1:1000
geometric scale and floor level configurations to represent the
cliff and its downwind roughness. The data at the TA determined
that the roughness velocity u* was equal to 0.32 ± 0.13 m/s (0.46
± 0.11 m/s) during the rainy (dry) period, while the roughness
length z0 equalled 0.19 ± 0.32 m (0.06 ± 0.05 m) for the rainy
(dry) period, thus showing the seasonality of the wind profiles.
The exponent \α of the velocity power law varied along the
yearly months from 0.19 to 0.27, with R2s between 0.88 and 0.99;
\α decreased with the altitude zn. For a rainy month, the
validation of \α with 2004 2005 wind data showed estimated
velocities greater than the ones observed at the TA, which was
possibly due a weaker atmospheric neutrality; however, for a dry
month, these velocities were equivalent, thus implying a neutral
atmosphere. Finally, the predominant wind direction was from the
Northeast, followed by the ones from the North and the East. The
TV experiments, with 90° and 70° steps representing the cliff,
both with and without additional downwind roughness, did show: (i)
a perfect emulation of the ocean wind profile (\α = 0.15)
above the position of the step representing the cliff, through the
use of a upwind carpeted fetch to provide the necessary roughness;
(ii) that the highest Reynolds number possible, based on the
height of the cliff, was 6.52 x 104 inside this TV, while it
reached 3 x107 at the CLA thus, a more powerfull tunnel is needed
to emulate this last situation; (iii) that the values of \α
nearest to the ones obtained at the CLA resulted from the 90° step
experiment without any extra covering over the floor, except the
upwind carpet; (iv) that the fixing of cubes downwind of the step
resulted roughnesses much greater than the ones observed over the
CLA vegetation, so possibly emulating urban or industrial
situations; (v) that typical characteristics which occur downwind
a step were emulated, such as the dettachment and the posterior
reattachment of the flow, plus the formation of circulation
bubbles; (vi) that the use of more powerfull TVs would certainly
permit the emulation of the atmospheric behavior of the CLA.
Finally, with the use of a more powerfull TV, besides the
replication of the experiments of the present work, experiments
with wind incidences on the step with angles other than 90° should
be recommended.",
committee = "Alval{\'a}, Regina C{\'e}lia dos Santos (presidente) and Fisch,
Gilberto Fernando (orientador) and Girardi, Roberto da Mota
(orientador) and Gielow, Ralf and Acevedo, Ot{\'a}vio Costa",
copyholder = "SID/SCD",
englishtitle = "Atmospheric flow study in the Alcantara Launching Center, using
anemometric tower and wind tunnel measurements",
language = "pt",
pages = "137",
ibi = "6qtX3pFwXQZGivnK2Y/Qr5M8",
url = "http://urlib.net/ibi/6qtX3pFwXQZGivnK2Y/Qr5M8",
targetfile = "publicacao.pdf",
urlaccessdate = "15 jun. 2024"
}