Flow behaviour analysis and experimental investigation for emitter micro-channels

Wei, Zhengying; Cao, Meng; Liu, Xia; Tang, Yiping; Lu, Bingheng

doi:10.3901/cjme.2012.04.729

Cited by 36 publications

(31 citation statements)

References 4 publications

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“…Due to the small size and complicated structure of the flow path in emitters, existing research is mainly based on macrohydraulic tests (Li et al, 2005(Li et al, , 2006a(Li et al, , 2012aOzekici and Ronald, 1991;Wu et al, 2003), and there has been relatively little research focusing on the micro-fluid characteristics of the flow field in emitters (Li et al, 2005;Dan et al, 2011;Wei et al, 2012). But with the recent development of computational fluid dynamics (CFD), this kind of numerical simulation method has become the new and effective way to study the hydraulic and structural capacity of emitters (Wang and Wang, 2006).…”

Section: Introductionmentioning

confidence: 99%

Flow Characteristics and Pressure‐Compensating Mechanism of Non‐Pressure‐Compensating Drip Irrigation Emitters

Zhangzhong

Yang

Ren

et al. 2015

Irrigation and Drainage

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The flow regime index (x) is a key parameter for evaluation of the drip irrigation capacity of emitters. Developing an emitter with low x has become the goal for numerous emitter developers. Currently, the phenomenon shows that the x of some nonpressure-compensating (non-PC) drip irrigation emitters are less than 0.5, which cannot be easily explained by the macropipeline hydraulic principle. Therefore, in this paper, we adopted the standard k-ε model to calculate and analyse the internal flow field of four non-PC emitters (with x all less than 0.5). The results indicated that the flow fields within these flow paths had obvious self-compensating effects. It showed that when work pressure increased, the flow characteristics changed correspondingly: the area of the low-speed vortex region expanded incrementally, resulting in shrinkage of the width of the flow crosssection in the high-speed mainstream region, also inhibiting the increments of emitter outflow rates and alleviating the influence of pressure variation on outflow raters, and finally reducing the value of x. When the pressure increased from 10 to 150 kPa,the maximum shrinkage of flow cross-section (R max , the flow cross-section shrinkage rate under the work pressure, increased from 10 to 150 kPa) of emitters S1, M1, M2 and M3 was 32.0, 16.4, 13.8 and 10.3%, respectively. R max had a significantly negative linear relationship with x. As R max increased, the adjustment range of the flow cross-section became greater and sensitivity of the regulating flow improved. Then the x of the non-PC emitter declined, indicating higher self-compensating capacity of the emitter. Copyright © 2015 John Wiley & Sons, Ltd. Ils ont montré qu'en cas d'augmentation de la pression, les caractéristiques de l'écoulement sont modifiées comme suit: le domaine de la zone de vortex à basse vitesse s'étend de façon incrémentielle, ce qui entraîne le rétrécissement de la largeur de la section d'écoulement à grande vitesse, ce qui par voie de conséquence inhibe les augmentations du débit de sortie des émetteurs tout en atténuant l'influence de la variation de pression sur l'écoulement. A la fin, la valeur de x est réduite. Lorsque la pression a augmenté de 10 à 150 kPa, la contraction maximale de section transversale d'écoulement (R max ) des quatre émetteurs S1, M1, M2 et M3 était de 32.0, 16.4, 13.8 a été agrandie et la sensibilité de réglage de débit améliorée. Ensuite, le x de l'émetteur non compensé a diminué, ce qui démontre la capacité d'autocompensation de l'émetteur.

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Section: Introductionmentioning

confidence: 99%

Flow Characteristics and Pressure‐Compensating Mechanism of Non‐Pressure‐Compensating Drip Irrigation Emitters

Zhangzhong

Yang

Ren

et al. 2015

Irrigation and Drainage

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“…Assuming that clogging is mainly influenced by particle size, one practical recommendation consists of adding a sieve or filter able to trap particles larger than those required to avoid emitter clogging. On the other hand, the idea that concentration of particles is highly significant in clogging severity is also supported by a previous study which observed that the filtration level of screen filters is determined as 1/7 – 1/10 of the labyrinth's channel width [15]. The same study also reported that sand particles larger than 1/5 of the channel width plugged emitters, while particles between 1/5 and 1/7 of the channel width caused a partial clogging of drippers during evaluations.…”

Section: Resultsmentioning

confidence: 68%

“…In addition, A2 has the largest dimensions of flow path among the evaluated models of drippers (Table 1). Specifically for rectangular section channels, the width and depth of the labyrinth channels were reported to enhance clogging resistance performance [15]. …”

Section: Resultsmentioning

confidence: 99%

Methodology to Evaluate Dripper Sensitivity to Clogging due to Solid Particles: An Assessment

Lavanholi

Oliveira

Camargo

et al. 2018

The Scientific World Journal

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Emitter clogging is a major problem in microirrigation systems, which may result from the isolated or combined effects of physical, chemical, and biological agents. Clogging caused by suspended solid particles is the most common plugging form of emitters. Water quality and emitter geometry are key aspects in clogging processes. Any suitable test procedure to assess the sensitivity of drippers to clogging should take into account the predominant factors that influence clogging and must reproduce the field conditions. This research set out to assess the performance and suitability of a laboratory clogging test procedure in order to validate a methodology and to provide scientific results that may support the standardization of a clogging test method. The evaluated methodology has been used by the IRSTEA laboratory since 1974 (Platform of Research and experiment on Science and Technology for Irrigation - PReSTI, formerly LERMI) and its contents are currently being discussed by the ISO TC23/SC18 committee. The aim is to define a standardized testing protocol to evaluate the sensitivity of emitters to clogging due to solid particles. Replications analyzing the clogging resistance of four models of emitting pipes were carried out in a laboratory. The clogging test procedure enabled an accurate assessment of the combinations of concentration and size of particles that caused clogging in each model of dripper. However, a significant variability in degree of clogging was identified when the results of replications for each model of dripper were compared. Several requirements, concerns, and improvements related to the clogging test protocol were discussed.

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“…The use of groundwater and surface water for irrigation is widespread. According to Pitts et al (1990), Nakayama and Bucks (1991) and Wei et al (2012), even if precipitation and filtration properly treat groundwater and river water, suspended particulates smaller than 0.076 mm may still pass through the filter system into the emitter channel. Additionally, the suspended particulate matter in the water is prone to physical flocculation with drip fertigation, which becomes a bridge between microbial growth and chemical adsorption.…”

Section: Introductionmentioning

confidence: 99%

Effect of fertilization and sediment flow hydraulic characteristics on emitter clogging in muddy water drip fertigation system^†

Liu

Niu

et al. 2018

Irrigation and Drainage

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In a drip fertigation system using the Yellow River, suspended solids in the water serve as a bridge between physical flocculation and chemical adsorption. They impact the emitter clogging process and flow turbulence properties. Therefore, a laboratory test was conducted with artificial muddy water drip fertigation (MWF) to investigate the anti‐clogging performance of emitters. Four types of fertilizer (i.e. [CO (NH2)2], Ca (H2PO4)2·H2O, K2SO4 and [CO (NH2)2] + KH2PO4 + KNO3) were applied at 0.5, 1, 2 and 3% concentrations respectively. The results showed that the relative discharge of emitters (Dra) remained in a fluctuation balance phase, and at 0.5% concentration with MWF, there was a decrease of 5, 11.1, 8.8 and 4.9%. For fertigation concentrations between 1 and 2%, the fluctuation balance phase significantly reduced, and the Dra began a linear decrease of 12.5, 42.2, 37.6 and 5.1%. At a fertilizer concentration increase of 3%, the Dra improved relatively with urea and P fertilizer drip irrigation but slightly declined with K and compound fertilizer. The particle size distribution of flocs ranked from broad to narrow as follows: P fertilizer > K fertilizer > urea > compound fertilizer. Urea showed a viscosity‐reducing effect on muddy water (MW). Conversely, K fertilizer exhibited the greatest viscosity‐increasing effect, followed by P fertilizer, while compound fertilizer exhibited the least viscosity‐increasing effect. The filter criteria of the drip irrigation system can be suitably reduced for drip fertigation with urea in the Yellow River irrigation area. © 2018 John Wiley & Sons, Ltd.

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Flow behaviour analysis and experimental investigation for emitter micro-channels

Cited by 36 publications

References 4 publications

Flow Characteristics and Pressure‐Compensating Mechanism of Non‐Pressure‐Compensating Drip Irrigation Emitters

Flow Characteristics and Pressure‐Compensating Mechanism of Non‐Pressure‐Compensating Drip Irrigation Emitters

Methodology to Evaluate Dripper Sensitivity to Clogging due to Solid Particles: An Assessment

Effect of fertilization and sediment flow hydraulic characteristics on emitter clogging in muddy water drip fertigation system^†

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Flow behaviour analysis and experimental investigation for emitter micro-channels

Cited by 36 publications

References 4 publications

Flow Characteristics and Pressure‐Compensating Mechanism of Non‐Pressure‐Compensating Drip Irrigation Emitters

Flow Characteristics and Pressure‐Compensating Mechanism of Non‐Pressure‐Compensating Drip Irrigation Emitters

Methodology to Evaluate Dripper Sensitivity to Clogging due to Solid Particles: An Assessment

Effect of fertilization and sediment flow hydraulic characteristics on emitter clogging in muddy water drip fertigation system†

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Effect of fertilization and sediment flow hydraulic characteristics on emitter clogging in muddy water drip fertigation system^†