AN EXPERIMENTAL STUDY OF VORTEX FLOW FOR APPLICATION TO GAS-PHASE FISSION HEATING

An experimental investigation into the gas dynamics of a jet-driven vortex tube for application of a cavity nuclear reactor to rocket propulsion has shown that viscous retardation of the vortex motion is severe, because of a high level of turbulence near the periphery. Based on the experience gained in this study, it is estimated that the achievement of vortex strengths sufficient for practical application will require the use of small diameter tubes with appreciable expenditure of power for recirculation of the gas. The effect of the high degree of turbulence on the separation process near the periphery remains to be determined. The independent variables which were found to influence the vortex strength significantly for a given gas and temperature condition are the tube diameter, the mass flow rate per unit tube length, the injection velocity, and the wall pressure. Estimates of the degree of turbulence in vortex flow have been made from data on the variation in tangential velocity with radius. Virtual (total) viscosities near the periphery ranged from 30 to 700 times the molecular viscosity for tangential Reynolds numbers of from 4 x 10/sup 4/ to 2 x l0/sup 6/. Measurements of the position of the mole- fraction peak for separation of helium and a heavy vapor agreed with the theory for laminar flow. This suggests that near the center of the vortex tube where the peak developed the radial density gradient was sufficiently strong to suppress turbulence. It is concluded that the vortex reactor concept appears promising for application to nuclear rocket propulsion provided a satisfactory method can be devised for recirculation of the large excess mass flow required to maintain the vortex strength, and if turbulence does not appreciably limit the separation process. A separation experiment at elevated temperature appears to be the next logical step in the research program. (auth

Ganho de peso e evolução do rebanho de queixadas selvagens em sistemas de criação semi-extensivo e extensivo, em reserva de Cerrado Weight gain and evolution of a wild white-lipped peccaries under extensive and semi-extensive systems, on a Savanna area

A utilização de comedouros automáticos com milho em grão foi testada como técnica para efetuar recaptura, marcação e manejo de queixadas (Tayassu pecari) reintroduzidas em área de Cerrado. Através desta técnica pôde-se comparar o ganho de peso de animais manejados em sistema extensivo (em liberdade) e em sistema semi-extensivo (restritos a uma área de 15 ha), bem como verificar aspectos da biologia reprodutiva da espécie. O manejo de queixadas através do sistema extensivo, demonstrou proporcionar um maior ganho de peso aos animais. Os comedouros automáticos com milho em grão, além de se mostrarem eficientes para a atração e agregação dos queixadas, proporcionou uma suplementação de energia. Através da marcação e recaptura dos indivíduos conseguiu-se verificar que esses animais se reproduzem durante todo o ano, gerando 1,57 filhotes /fêmea /parto, com diferenciação entre sexos de 50%. A produtividade bruta no sistema semi-extensivo foi de 1,4 e a fecundidade bruta de 0,6. A adoção do sistema extensivo para o manejo de queixadas, pode ser uma solução para a exploração sustentável da espécie, principalmente em regiões onde esse recurso é utilizado como fonte de subsistência através da caça ilegal.<br>The use of automatic feed barrel with grain corn as a methodology to mark, recapture and management of white-lipped pecaries (Tayassu pecari) reintroduced on a Savanna area located at Mato Grosso do Sul State was tested. Using this technique we could compare the weight gain managing animals on extensive (freedom on the area) and semi-extensive systems (restricted to a 15ha area), and examine reproductive biology aspects of this specie. The management of white-lipped peccaries on the extensive system provided a greater weight gain to the animals. The automatic feed barrel with grain corn showed to be efficient to attract and aggregate the white-lipped peccaries but also provided supplemental energy. Using the mark and recapture method we could note that this animals reproduce all over the year, breeding 1,57 pig-lets/female/parturition, with the proportion between sex of 50%. Gross productivity was 1,4 and gross fecundity = 0,4. The adoption of extensive systems to manage white-lipped peccaries could be a solution to sustainable exploration of this specie at places where this resource is explored as a subsistence source through illegal hunting