Carlos A. V. de Azevedo

Efeito de uso de águas residuárias sobre a vazão de microaspersores

The study was conducted with the objective of evaluating the hydraulic characteristics of microsprinklers after use with wastewater treated by an upflow anaerobic sludge blanket (UASB anaerobic reactor) and a polishing pond during a period equivalent to two years. The hydraulic characteristics determined for the new and used emitters were the following: manufacturing coefficient of variation, coefficient of use and the discharge-pressure head equation. The results indicated no appreciable variations after using wastewater. The value of the mean discharge for nominal pressure was reduced by 4.97% in relation to the new. The flow regime did not change and the variation coefficient increased but continued being of excellent category as per ASAE classification.

Escoamento uniforme em canais circulares lisos. Parte I: adaptação e validação do método de Kazemipour

Considering the von Karman Prandtl equation for pressurized tubes, Kazemipour & Apelt (1980) developed a methodology for flow calculation in smooth circular channels, denominated as method of Kazemipour. Inspite of good results, the Kazemipour method needs graphic tools in its application, which makes its solution through computational methods and comparison to other existing methodologies difficult. In this research, the results of the analytic investigation that provides the validation of the Kazemipour method are shown, as well as the adjustments according to procedure proposed by Silva & Figueiredo (1993), performed in such a way to make the procedure independent of graphic tools. The result obtained is satisfactory and its use is presented in an example of practical application.

Reflexos da variabilidade espacial e temporal da fase de avanço e do tempo de oportunidade de infiltração no tempo de aplicação d'água na irrigação por sulcos para um solo franco-arenoso

Esta pesquisa teve como objetivo verificar as variabilidades espaciais e temporais no tempo de avanco e no tempo de oportunidade de infiltracao dagua e seus reflexos no tempo de aplicacao dagua num sistema de irrigacao por sulcos com fluxo reduzido para um solo franco-arenoso. As avaliacoes de campo foram realizadas no perimetro irrigado de Sao Goncalo, Sousa - PB, onde foram feitas medicoes em seis sulcos, equidistantes, de forma a abranger o maximo possivel a variabilidade em toda a area, nos 12 eventos de irrigacao da estacao de cultivo. Observando os tempos de avanco e de oportunidade de infiltracao d`agua no final da area irrigada em cada evento e em cada sulco ao longo do tempo, verificou-se que a variacao espacial no tempo de avanco foi mais expressiva que a variacao temporal, enquanto no tempo de oportunidade de infiltracao d`agua ocorreu o inverso. Ao longo do tempo e do espaco, os valores minimo e maximo do tempo de avanco e do tempo de oportunidade de infiltracao d`agua foram, respectivamente, 15 e 62 min, e 1 e 517 min. Essas amplitudes nos referidos tempos geraram variacoes espaciais maximas no tempo de aplicacao dagua, ao longo da estacao de cultivo, igual a 41,8%; espacialmente, as variacoes temporais maximas no tempo de aplicacao foram de 71,6%. Esses valores mostram o quanto a heterogeneidade das caracteristicas de infiltracao d`agua, bem como da vazao, do perimetro molhado dos sulcos e da lâmina requerida ao longo do tempo e do espaco, afeta a otimizacao do tempo de aplicacao d`agua.

Escoamento uniforme em canais circulares lisos. Parte II: comparação entre o método de Kazemipour e a equação de Manning

The Chezy-Manning equation as well as several other equations used in the calculation of the uniform flow in channels does not represent satisfactorily the shape effect of the flow cross-sectional area, which results in little precision. A methodology developed by Kazemipour & Apelt (1980), considering the von Karmam Prandtl equation for pressurized tubes, denominated as method of Kazemipour, has showin quite efficient in the calculation of the flow in smooth circular channels. In this research, the method of Kazemipour, numerically adjusted was confronted with the Manning equation. In the analysis, discharge values calculated by the two methodologies and reliable experimental data were used. According to the evaluated parameters, the method of Kazemipour showed to be superior to Mannings equation for flow calculation in smooth circular channels.

Tubo de PVC liso com diferentes envoltórios como material alternativo na drenagem subterrânea

In irrigated arid and semi-arid regions the drainage is, frequently, necessary to prevent the waterlogging of the soil and to control the salinity. One of the main obstacles in the installation of a subsurface drainage system is the high cost of the initial investment. Thus, some contribution that reduces the cost of the installation of the drains and also of the material used is highly advantageous. The objective of this research was to evaluate, under laboratory conditions, the hydraulic performance of the drainage system constituted by smooth PVC tube used for sewer with 50.0 mm of nominal diameter and open area of 23.0 cm2 m-1 and different types of envelopes, as an alternative material for subsurface drainage. The performance of the smooth PVC tube demonstrated that this material is technically viable for agricultural drainage principally when used with single stones as envelope.