Ana Cristina Avelar

Analysis of the Ocean Boundary Layer influence on the Mobile Tower Integration at the Alcantara Space Center

This work presents a numerical and experimental analysis of the Ocean Boundary Layer (OBL) influence on the formation of the Internal Boundary Layer (IBL) at the Alcantara Space Center (ASC), from where the Brazilian rockets are launched. The numerical simulation was carried out considering a two-dimensional flow with velocity-vorticity formulation for Navier Stokes equations. A 6th order compact finite differences scheme was used for spatial discretization and a 4th order Runge-Kutta scheme with temporal integration. The coastal cliff along the shoreline in the ASC neighborhood was specified trough the immersed boundary technique. The experimental analysis was carried out in a subsonic wind tunnel using a twodimensional Particle Image Velocimetry (PIV) system. The measurements were carried out considering the irregularity of the coastal cliff. The results confirmed that OBL height influences the height of Internal Boundary Layer that reaches the Mobile Integration Tower (MIT).

Estudo do escoamento turbulento atmosférico utilizando ensaios em túnel de vento e simulação numérica

The structure of the wind field and atmospheric turbulence generated inside a shallow cavity is analyzed using wind tunnel tests and a 2-D Large-Eddy Simulation (LES) model. The cavities are static mock-up that can represent small clearings inside forest in Amazonia or urban canyons representing the geometry of modern cities. The results suggest that, despite differences in the scales, the organization of turbulence in the two experiments contains similarities in some regions. It was verified the dependency of the turbulence, wind profile and Turbulent Kinetic Energy dependence against flow above canopy, its size and its relative position inside the gap.

PERFIS DE VENTO E TURBULÊNCIA ATMOSFÉRICOS SIMULADOS EM TÚNEL DE VENTO

O perfil de vento e a turbulencia foram estudados a partir de medidas obtidas com um anemometro de fio quente em ensaios de tunel de vento com um modelo de cavidade rasa. Foi determinada a Escala Integral Euleriana e os resultados sugerem que a estrutura da turbulencia e controlada, principalmente, pela entrada de energia a sotavento da cavidade.

ANÁLISE DA INFLUÊNCIA DA ESTRATIFICAÇÃO SOBRE PERFIS DE VENTO E TEMPERATURA EM EXPERIMENTOS DE TÚNEL DE VENTO

Este trabalho relata um escoamento estratificado e turbulento, no qual a superficie e mais fria que o ambiente sobre ela. Dessa forma, verifica-se a influencia da estratificacao sobre os perfis de vento e temperatura.

Wind Tunnel Analysis of the Wind Incidence Angle in the Flow Pattern in the Centro de Lançamento de Alcântara

In Brazil, most of the launching vehicles and rockets are launched from the Centro de Lancamento de Alcântara, CLA, which is a launch site with several favorable features, mostly due its privileged location, very close to the Equator line. #evertheless, the CLA topology has a coastal cliff occurrence of about 40m high at the edge of the sea land, which can modify the atmospheric boundary layer characteristics, and consequently affect the safety during launching operations, given that the rockets launch pad and the Mobile Integration Tower (MIT), the building where the space vehicles are assembled, is located around 150 – 200 m from the sea border, respectively. In continuation to previous studies, the main purpose of the present work is to investigate, experimentally, the effects of the wind incidence angles, taking into account the irregular cliff topology, on the mean wind flow pattern around the MIT neighborhood. Wind tunnel measurements using the Particle Image Velocimetry (PIV) technique were conducted for Reynolds number (Rel) values based on the cliff height, l, of 5.4x10 5 , 1.4x10 6 and 2.0x10 6 . The results obtained indicate that the investigated parameters, cliff slope and the wind incidence angle, play a significant role in the flow features in the CLA launching system. The size of the recirculation bubble, in case of flow separation, as well as the vorticity intensity at the cliff edge and in the MIT neighborhood can be quite different depending on these parameters. It seems that steeper the cliff slope, θ, stronger is the flow separation at the cliff edge, and weaker is the vortexes formed behind the MIT.

Atmospheric Boundary Layer Simulation in a Wind Tunnel for Analysis of the Wind Flow at the Centro de Lançamento de Alcântara

The Centro de Lancamento de Alcântara (CLA) is the main Brazilian Launching Center. In spite of presenting several desirable aspects due to its proximity of the Equator, it has a peculiar topography due to the existence of a coastal cliff, which modifies the characteristics of the atmospheric boundary layer (ABL) in a way that can affect rocket-launching operations. This work is a continuation of previous experimental studies about the flow pattern at CLA and presents an improved way for simulation of an atmospheric boundary layer in a short test section wind tunnel. PIV flow maps around the coastal cliff and the Mobile Integration Tower (MIT).

STUDIES USING WIND TUNNEL TO SIMULATE THE ATMOSPHERIC BOUNDARY LAYER AT THE ALCÂNTARA SPACE CENTER. doi:10.5028/jatm.2009.01019198

The Alcântara Space Center (ASC) region has a peculiar topography due to the existence of a coastal cliff, which modifies the atmospheric boundary layer characteristic in a way that can affect rocket launching operations. Wind tunnel measurements can be an important tool for the understanding of turbulence and wind flow pattern characteristics in the ASC neighborhood, along with computational fluid dynamics and observational data. The purpose of this paper is to describe wind tunnel experiments that have been carried out by researchers from the Brazilian Institutions IAE, ITA and INPE. The technologies of Hot-Wire Anemometer and Particle Image Velocimetry (PIV) have been used in these measurements, in order to obtain information about wind flow patterns as velocity fields and vorticity. The wind tunnel measurements are described and the results obtained are presented.