Navegando por Autor "BRASIL JUNIOR, Antonio Cesar Pinho"

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Acesso aberto (Open Access)
Evento extremo de chuva-vazão na bacia hidrográfica do rio Araguari, Amapá, Brasil
(Universidade Federal do Pará, 2014-12) CUNHA, Alan Cavalcanti da; VILHENA, Jefferson Erasmo De Souza; SANTOS, Eldo Silva Dos; SARAIVA, Jaci Maria Bilhalva; KUHN, Paulo Afonso Fischer; BRITO, Daímio Chaves; SOUZA, Everaldo Barreiros de; ROCHA, Edson José Paulino da; CUNHA, Helenilza Ferreira Albuquerque; BRITO, Alaan Ubaiara; BRASIL JUNIOR, Antonio Cesar Pinho; PACA, Victor Hugo da Motta; SANTOS, Paula Verônica Campos Jorge
The objective of this investigation was to analyse the extreme river flows which have occurred between 9 and 14 April 2011 in the Rio Araguari-AP. The methodology consisted of three main steps: 1) re-analysis of precipitation estimated by the BRAMS (Brazilian Development in Regional Atmospheric Model System) model using the synoptic of the same period as support, 2) analysis of streamflow in sections of hydrological monitoring in Porto Platon, Capivari and Serra do Navio (ADCP-Accustic Profiller Doppler Current); 3) statistic analysis of the time series of maximum river flows in Porto Platon using Gumbel distribution. It was observed that the BRAMS system partially captured the standard precipitation when compared with the synoptic analysis and literature data, but the extreme hydrological responses representation still needs an optimization. In Porto Platon a flow record of 4036 m3 /s was recorded, whose behavior was analyzed from the perspective of the available monitoring mechanisms in the State. It was concluded that such extreme events are poorly detectable and offer considerable risks to users of the basin. The stream flow prediction based on available hydrological series was 100 years recurrence, but the analysis have revealed that this period would be 360 years, indicating significant deficiency of the prediction system of extreme events in the State.
Acesso aberto (Open Access)
Numerical Study of Wake Characteristics in a Horizontal-Axis Hydrokinetic Turbine
(Universidade Federal do Pará, 2016-12) SILVA, Paulo Augusto Strobel de Freitas e; OLIVEIRA, Taygoara Felamingo de; BRASIL JUNIOR, Antonio Cesar Pinho; VAZ, Jerson Rogério Pinheiro
Over the years most studies on wake characteristics have been devoted to wind turbines, while few works are related to hydrokinetic turbines. Among studies applied to rivers, depth and width are important parameters for a suitable design. In this work, a numerical study of the wake in a horizontal-axis hydrokinetic turbine is performed, where the main objective is an investigation on the wake structure, which can be a constraining factor in rivers. The present paper uses the Reynolds Averaged Navier Stokes (RANS) flow simulation technique, in which the Shear-Stress Transport (SST) turbulent model is considered, in order to simulate a free hydrokinetic runner in a typical river flow. The NREL-PHASE VI wind turbine was used to validate the numerical approach. Simulations for a 3-bladed axial hydrokinetic turbine with 10 m diameter were carried out, depicting the expanded helical behavior of the wake. The axial velocity, in this case, is fully recovered at 12 diameters downstream in the wake. The results are compared with others available in the literature and also a study of the turbulence kinetic energy and mean axial velocity is presented so as to assess the influence of proximity of river surface from rotor in the wake geometry. Hence, even for a single turbine facility it is still necessary to consider the propagation of the wake over the spatial domain.