Modelagem das perdas de água por evaporação e arraste de sprays de placa oscilante

Abstract

R E S U M ODentre os diversos fatores que influenciam as perdas de água por evaporação e arraste (PEA) destaca-se o vento. Sendo assim, os objetivos deste trabalho foram: i) determinar os valores de PEA decorrentes de onze avaliações de um sistema de irrigação do tipo pivô central; ii) gerar um modelo para estimativa de PEA a partir de variáveis explicativas; iii) avaliar modelos de predição disponíveis na literatura para estimar PEA a partir de ensaios de campo. Os ensaios foram realizados ao longo de um vão de 48 m, situado entre a quarta e quinta torre de um pivô central de 432,57 m de raio, equipado com sprays de placa oscilante modelo I-Wob. As PEA foram simuladas em função de cinco modelos empíricos propostos na literatura sendo ainda ajustado um modelo específico para a condição estudada. As avaliações de campo em diferentes condições meteorológicas demonstraram que os valores das PEA obtidos com modelos existentes na literatura apresentaram índices de adequabilidade insatisfatórios para as condições estudadas porém o modelo de PEA ajustado apresentou menores erros quando comparado aos modelos existentes, podendo ser utilizado para condições operacionais e climáticas semelhantes às observadas neste estudo.Modeling of evaporation and wind drift losses in rotating spray plate sprinklers A B S T R A C TAmong several factors that exert influence on evaporation and wind drift losses (EWL), the wind has attracted researcher's attention in scientific studies. In this context, the objectives of this study were: i) to determine EWL that occurred in eleven field tests with a center pivot system; ii) to develop a model to estimate EWL in function of predictor variables; iii) to evaluate prediction models available in literature for estimation of EWL from data acquired in the field trials. The tests were carried out along a 48-m span located between the fourth and fifth tower of a center pivot of 432.57 m in length, equipped with a model of rotating spray plate sprinklers known as I-Wob. Evaporation and wind drift losses were simulated using five empirical models. Additionally, a specific model was developed for the operational and meteorological conditions observed in this study. It was found that the empirical models presented unsatisfactory performance indices when they were tested for the operational and meteorological conditions observed in this study. The errors obtained from the adjusted model were lower than those observed when using the existing models. Thus, this model can be used for conditions similar to those experienced in this study.

Predictive Models of Water Application and Distribution Efficiency in Conventional Sprinkling

“…Several studies have been conducted in different Engenharia Agrícola, Jaboticabal, v.40, n.1, p.24-33, jan./feb. 2020 regions of the world with the purpose of modeling or evaluating some existing models for WDEL estimation in sprinkler irrigation systems (Colombo et al, 2015;Faria et al, 2012;Stambouli et al, 2013).…”

“…According to Colombo et al (2015), knowledge of the performance of an irrigation system, especially regarding the uniformity of distribution of the applied water depth, is essential for making decisions that allow the rational use of water, energy, and fertilizers. Thus, knowing the influence of weather variables is essential to predict or estimate irrigation uniformity, and even to identify the best time for the operation of a sprinkler irrigation system.…”

Advances in Sprinkler Irrigation: A Review in the Context of Precision Irrigation for Crop Production

“…The researchers' findings provide evidence that the scale of wind drift depends on wind speed and weather conditions [117,118] and it varies from 3.6 to 7.2% [119]. Colombo et al reported 3.38% losses of wind drift under the regular operation of CPS [120]. The variation in wind drift was examined by Playan et al in a number of experiments (52 in 2004 and 39 in 2005) and reported the range of the magnitude of losses as 4.3-14.7 in 2004 and 0.3-8.3% in 2005 [121].…”

Dynamics of Water Vapor Content around Isolated Sprinklers: Description and Validation of Model

“…Many studies have shown that meteorological conditions have a significant influence on WDELs. Thus, many empirical models have been developed to estimate WDELs by using wind speed as a single variable [22][23][24]28,[33][34][35], and several models have included wind speed and other meteorological variables, such as temperature [13,23,27], relative humidity [23] and vapor pressure deficit [21,36] as parameters. Theoretical models have also been built to incorporate droplet ballistics dynamics and evaporation [37,38].…”