Numerical simulation of a radial diffuser turbulent airflow

In the present work are presented results from numerical simulations performed with the ANSYS-CFX (R) code. We have studied a radial diffuser flow case, which is the main academic problem used to study the flow behavior on flat plate valves. The radial flow inside the diffuser has important behavior such as the turbulence decay downstream and recirculation regions inside the valve flow channel due to boundary layer detachment. These flow structures are present in compressor reed valve configurations, influencing to a greater extent the compressor efficiency. The main target of the present paper was finding the simulation set-up (computational domain, boundary conditions and turbulence model) that better fits with experimental data published by Tabatabai and Pollard. The local flow turbulence and velocity profiles were investigated using four different turbulence models, two different boundary conditions set-up, two different computational domains and three different flow conditions (Re-in - Reynolds number at the diffuser inlet). We used the Reynolds stress (BSL); the k-epsilon; the RNG k-epsilon; and the shear stress transport (SST) k-omega turbulence models. The performed analysis and comparison of the computational results with experimental data show that the choice of the turbulence model, as well as the choice of the other computational conditions, plays an important role in the results physical quality and accuracy. (c) 2007 Elsevier B.V. All rights reserved.

Pressure distribution on the frontal disk for turbulent flows in a radial diffuser

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The use of mechanical aeration and its effects on water mass

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Analysis of the different forms of application and types of cutting fluid used in plunge cylindrical grinding using conventional and superabrasive CBN grinding wheels

The work reported here involved an investigation into the grinding process, one of the last finishing processes carried out on a production line. Although several input parameters are involved in this process, attention today focuses strongly on the form and amount of cutting fluid employed, since these substances may be seriously pernicious to human health and to the environment, and involve high purchasing and maintenance costs when utilized and stored incorrectly. The type and amount of cutting fluid used directly affect some of the main output variables of the grinding process which are analyzed here, such as tangential cutting force, specific grinding energy, acoustic emission, diametrical wear, roughness, residual stress and scanning electron microscopy. To analyze the influence of these variables, an optimised fluid application methodology was developed (involving rounded 5, 4 and 3 turn diameter nozzles and high fluid application pressures) to reduce the amount of fluid used in the grinding process and improve its performance in comparison with the conventional fluid application method (of diffuser nozzles and lower fluid application pressure). To this end, two types of cutting fluid (a 5% synthetic emulsion and neat oil) and two abrasive tools (an aluminium oxide and a superabrasive CBN grinding wheel) were used. The results revealed that, in every situation, the optimised application of cutting fluid significantly improved the efficiency of the process, particularly the combined use of neat oil and CBN grinding wheel. (c) 2005 Elsevier Ltd. All rights reserved.

Gênero, sexualidade e educação formal no Brasil: uma análise preliminar da produção acadêmica entre 1990 e 2006

Cet article présente les résultats de la recherche Démocratisation de la connaissance: recherche de pointe sur le genre et l'éducation formelle comme soutien pour formuler des agendas et des actions de politiques gouvernementales et non gouvernementales. Développée entre 2006 et 2007, elle visait à met re à jour, systématiser et diffuser la connaissance accumulée dans la production universitaire brésilienne sur les liens entre l'éducation formelle et les thématiques du genre, des femmes et/ou de la sexualité. Une banque de données contenant le titre et le résumé de 1 213 dissertations, thèses et articles a été constituée. Nous soulignons autant les défis théoriques, concernant une meilleure compréhension des concepts étudiés par cete enquête, que les défis méthodologique, comme la définition des descripteurs et des sources devant être examinées. Sa conclusion présente des tableaux et graphiques qui tracent un portrait initial des documents disponibles dans la base de données et indiquent que ces thématiques ont été l'objet d'un intérêt croissant sur la période étudiée.

Simulation of the flow through automatic valves of hermetic compressors by the immersed boundary method approach

The main goal of the present work is to verify the applicability of the Immersed Boundary Method together with the Virtual Physical Model to solve the flow through automatic valves of hermetic compressors. The valve was simplified to a two-dimensional radial diffuser, with diameter ratio of D/d = 1.5, and simulated for a one cycle of opening and closing process with a imposed velocity of 3.0 cm/s for the reed, dimensionless gap between disks in the range of 0.07 < s/d < 0.10, and inlet Reynolds number equal to 1500. The good results obtained showed that the methodology has great potential as project tool for this type of valve systems. © The Authors, 2011.

A recepção das ideias estético-literárias de Lukács em Leandro Konder e Carlos Nelson Coutinho: análise de suas produções teórico-críticas

Pós-graduação em Ciências Sociais - FCLAR

Estudo experimental da interação fluido-estrutura em um modelo de válvula de compressor de refrigeração

Pós-graduação em Engenharia Mecânica - FEIS

Estudo experimental da interação fluido-estrutura no escoamento em um difusor radial

Pós-graduação em Engenharia Mecânica - FEIS

Modelagem numérica do escoamento em válvulas automáticas de compressores pelo Método da Fronteira Imersa

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Investigação numérica e experimental do escoamento em válvulas de compressores herméticos

Pós-graduação em Engenharia Mecânica - FEIS

Simulação numérica do escoamento em difusores radiais usando o método da fronteira imersa

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise termodinâmica, termoeconômica e econômica de uma usina sucroalcooleira com processo de extração por difusão

Pós-graduação em Engenharia Mecânica - FEIS

Caracterização histoquímica do colágeno e expressão de MMP-2, MMP-9 e TIMP-1 nas endometrites crônicas das éguas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Saldo de radiação obtido através de medida e estimativa por três modelos e a sua relação com o desenvolvimento da cultura de cravo-de-defunto (Tagetes sp.)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)