Quantificação do erro na determinação da perda contínua de carga em tubos elásticos

Neto, Osvaldo Rettore; Botrel, Tarlei Arriel; Frizzone, José Antônio; Pinto, Marinaldo Ferreira; Camargo, Antônio Pires de

doi:10.1590/s0100-69162013000600023

Cited by 6 publications

(5 citation statements)

References 9 publications

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“…Geralmente as equações superestimam as perdas de carga que ocorrem, pois as tubulações de polietileno, mais comumente utilizadas em sistemas de irrigação, aumentam seu diâmetro quando pressurizadas, diminuindo a perda de carga que é determinada (Rettore Neto et al, 2013).…”

Section: Introductionunclassified

Diferenças entre o Método Trecho-a-Trecho e o Método de Múltiplas Saídas na determinação das perdas de cargas em uma linha lateral de um sistema de irrigação localizada

Miranda¹,

Rosal²,

Lima³

2018

Rev. Bras. Gest. Amb. Sustent.

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A perda de carga é o parâmetro fundamental para o dimensionamento dos sistemas de irrigação. Sua determinação correta tem relação com os custos dos materiais e com o consumo de energia. Este trabalho teve como objetivo comparar a determinação das perdas de cargas em uma linha lateral de um sistema de irrigação localizada por microaspersão, usando o método de múltiplas saídas e o método trecho-a-trecho. No dimensionamento alterou-se o comprimento da linha lateral, aumentando consequentemente o número de aspersores e a vazão da linha lateral e a pressão de serviço, aumentando com isso a vazão da linha lateral e mantendo o mesmo comprimento e número de microaspersores por lateral. Tanto para o aumento do comprimento da linha lateral como para o aumento da pressão de serviço, a perda de carga determinada pelo método trecho-a-trecho foi maior que o método de múltiplas saídas, a maior diferença observada foi de 8,8%. A diferença entre os dois métodos aumentou a medida que o comprimento da linha lateral aumentou. O contrário aconteceu com o aumento da pressão de serviço, que provocou uma redução nas diferenças entre os dois métodos.

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Section: Introductionunclassified

Diferenças entre o Método Trecho-a-Trecho e o Método de Múltiplas Saídas na determinação das perdas de cargas em uma linha lateral de um sistema de irrigação localizada

Miranda¹,

Rosal²,

Lima³

2018

Rev. Bras. Gest. Amb. Sustent.

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“…When comparing the Blasius model without adaptations, it is observed that it proceeds with estimates of the friction factor with greater precision as the Reynolds number increases (Figure 1). At the flow in smooth pipes (as in the present study), the friction factor depends exclusively on the flow turbulence because the size of the roughness of the tube walls does not influence the flow turbulence, and the friction factor can be determined depending on the Reynolds number (Rettore Neto et al, 2013).

f = 0.1034 \cdot D^{- 0.256} \cdot {Re}^{- ((), 0.1593 \cdot D^{- 0.105})}

Through the Taylor diagram, it was possible to analyse the efficiency of the Blasius mathematical models to estimate the friction factor (Figure 2).…”

Section: Resultsmentioning

confidence: 85%

“…Frizzone et al (1998) also found good efficiency in estimating the head loss (considering the friction factor by the Blasius method) as the experimentally measured head loss. In uniform turbulent flow in smooth tubes, the size of the roughness does not influence the flow turbulence, and the friction factor is independent of the roughness of the inner walls of the pipe, which can be calculated according to the Reynolds number (Rettore Neto et al, 2013).…”

Section: Resultsmentioning

confidence: 99%

Modelling the Darcy–Weisbach friction factor and the energy gradient of the lateral line*

Jardim

Silva

et al. 2021

Irrigation and Drainage

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The objective was to adjust explicit mathematical models to determine the friction factor ( f ). Besides, an adaptation of the Blasius model is presented and an application of the Darcy-Weisbach equation to estimate the energy loss along the lateral line for four types of microsprinklers. f was determined by the model of Offor and Alabi and the model of Blasius for velocities between 0.5 to 3.0 m s À1 and internal pipe diameters of 0.0130, 0.0161, 0.0206, 0.0270, 0.0288, and 0.0368 m. The friction factor determined by Offor and Alabi was associated with the pipe diameters utilizing regression, and based on that an adaptation to the Blasius model was proposed. From the results of f, the energy and flow gradient along the lateral line for four NaanDanJain microsprinklers was simulated. The models of Offor and Alabi, Blasius, and Adapted Blasius showed excellent precision in determining f. The results of unit head loss, determined by the three mathematical models, showed dispersion close to zero among the pairs, showing a high correlation between the models (R 2 = 0.99).The Blasius equation is the most suitable to be inserted into the Darcy-Weisbach model to determine the maximum length of the lateral line.

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“…The pressure was maintained constant during all the tests at 20 mH2O varying only the flow velocity inside the piping to avoid changes in the pipe diameter which would cause errors in the correct estimation of the head loss values (Rettore Neto et al, 2013;Rettore Neto et al, 2014;Rettore Neto et al, 2016).…”

Section: Methodsmentioning

confidence: 99%

ESTIMATION OF THE KINETIC HEAD COEFFICIENT (k) BASED ON THE GEOMETRIC CHARACTERISTICS OF EMITTER PIPES

et al. 2017

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ABSTRACT:The objective of this study was to determine the variability of the head loss as a function of the emitter geometry as well as to develop a relation between local head loss caused by the emitter insertion and geometric characteristics of the emitter pipe, using index of obstruction for dripper pipes with non-coaxial emitters. For this, an experimental bench was developed to control the system and obtain the variables pertinent to the study. From the value of the total head loss in the emitter pipe and the value obtained with calculation of the distributed head loss in the pipe, the difference of these values was local head loss caused by the insertion of the emitter. Total head loss in the emitter pipe and local head loss on the emitter presented a potential relation with flow rate. The kinetic head coefficient (k), for each emitter studied, was obtained from the local head loss on the emitter and the kinetic head. A model for estimating the k coefficient based on the obstruction index was then generated.

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Quantificação do erro na determinação da perda contínua de carga em tubos elásticos

Cited by 6 publications

References 9 publications

Diferenças entre o Método Trecho-a-Trecho e o Método de Múltiplas Saídas na determinação das perdas de cargas em uma linha lateral de um sistema de irrigação localizada

Diferenças entre o Método Trecho-a-Trecho e o Método de Múltiplas Saídas na determinação das perdas de cargas em uma linha lateral de um sistema de irrigação localizada

Modelling the Darcy–Weisbach friction factor and the energy gradient of the lateral line*

ESTIMATION OF THE KINETIC HEAD COEFFICIENT (k) BASED ON THE GEOMETRIC CHARACTERISTICS OF EMITTER PIPES

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