Irrigation Emitters Research Articles

Using industrial computed tomography to determine the spatial distribution of clogging substances in drip irrigation emitter flow channels

AbstractDrip irrigation using poor‐quality water is effective for addressing agricultural water shortages, but it can lead to emitter clogging. However, little is known about the formation behaviour of clogging substances inside emitters when using reclaimed effluent. This study used industrial computed tomography (ICT) to determine the spatial distribution of clogging substances within emitter flow channels. The results showed that 21%–27% of the clogging substances were on the top face, and 20%–26% were on the substrate face, with less than 20% on the downstream and root faces. Clogging substances concentrated at the front of flow channels accounted for 38%–61% of the first structural unit. As the flow channel length increased, there was a significant fluctuation in the volume of clogging substances on the upstream and downstream faces, while changes on the upstream face, downstream face and root face exhibited relatively minor fluctuations. It is recommended to focus on controlling clogging substances on the top and substrate faces, as well as at the front of the emitter flow channel. These findings contribute to a better understanding of the spatial distribution of clogging substances in emitter flow channels, which is crucial for the development of anti‐clogging emitters and the promotion of poor‐quality water drip irrigation technology.

Effects of aeration on hydraulic and anti-clogging performance of subsurface drip irrigation emitters

Effects of aeration on hydraulic and anti-clogging performance of subsurface drip irrigation emitters

The design and hydraulic performance studies of a Tesla valve‐type drip irrigation emitter

The design and hydraulic performance studies of a Tesla valve‐type drip irrigation emitter

The Structural Optimization of Leaf Vein Drip Irrigation Emitter on Hydraulic Performance, Energy Entropy and Anti-Clogging Ability

Leaf vein drip irrigation emitter is a new type of drip irrigation emitter. The flow channel achieves energy dissipation through flow diversion, turning, and sudden contraction. In this study, three design schemes (B1, B2, and B3) were proposed by optimizing the flow channel structure to improve the hydraulic performance, and the feasibility of the schemes was verified by combining them with experiments. The results show that the flow index of the three structural optimization designs were 0.52, 0.51, and 0.50, with errors of less than 5% compared to the measured results. Compared to the original structure A1 (with a flow index of 0.53), the hydraulic performance was improved by 0.4%, 3.2%, and 5.7%. Compared with A1 and B1, the turbulence kinetic energy of the main flow region of the B2 and B3 structures was significantly increased, and the proportion of low turbulence kinetic energy area had decreased. The increase in turbulent kinetic energy drove the liquid to remain turbulent, increasing the ability of particulate matter to flow out of the flow channel. The irregular changes in the velocity field in the high-speed zone result in a large velocity gradient, which maximizes the turbulent kinetic energy and entropy generation in the area. Among the four flow channel structures, the region with the highest turbulence dissipation was located in the upper part of the internal structure of the flow channel. There were apparent vortex regions in flow channels A1, B1, and B3 for energy dissipation, with energy dissipation coefficients being 6.07–8.51. However, the average flow velocity in this region was only about 0.2 m/s, and particulate matter was easily trapped. When the particle diameter increased, compared with the other three design structures, B2 had the best particle passage ability. Combined with the muddy water experiment, the optimized flow channel B2 anti-clogging performance improved by 30.8%. This study can provide a reference for further improving the hydraulic performance of drip irrigation emitters.

Analysis of anti-clogging performance and particle transport characteristics of a stellate irrigation emitter

The service life and irrigation efficiency of drip irrigation systems are largely determined by the anti-clogging performance of the emitters. The degree and speed of clogging of the emitters are governed by the motion state of the particles in the flow channel. Computational fluid dynamics coupled discrete element method (CFD-DEM) and experiments were used to analyse anti-clogging performance and particles transport characteristics of a stellate irrigation emitter. With the angle of repose of sediment particles as the optimization objective, the key parameters of physical properties of sediment particles and container were obtained in the discrete phase model using a Plackett-Burman test, steepest climb test and Box-Behnken test. A novel evaluation method for assessing anti-clogging performance based on particles mass passing rate is proposed and its accuracy experimentally verified. Using three particles groups with different particle size distributions, the anti-clogging performance of stellate emitter was found to better than the widely used toothed emitter. In particular, the anti-clogging performance of the stellate emitter was found to be superior with the sensitive particle size of 0.03 mm. It was shown that sediment particles demonstrated retention, bonding and deposition in the inlet far away from the flow channel, the backwater area at the vertical vertex of the stellate structure and the backwater area at the joint of the stellate emitter flow channel structure units.

Numerical simulation and structure optimization for hydraulic performance of perforated drip irrigation emitters

ABSTRACT The perforated drip irrigation emitter (PDIE) is a novel drip irrigation emitter incorporating multiple energy dissipation mechanisms, chiefly hedging, deflection, and friction. To characterize the influences of structural parameters and vortices on the hydraulic performance of PDIE, the discharge exponent, discharge rate, and emitter unit constant were analyzed via hydraulic performance experiments and numerical simulation. The key findings are: (1) Discharge exponents of PDIE ranged from 0.478 to 0.515; average high-pressure hydraulic performance exceeded low pressure by 4.882%. (2) The four key structural parameters impacted hydraulic performance from large to small as follows: the width of the perforation (a), the angle of the scalariform perforation plate (α), the distance of the two perforations (b), and the length of the channel cavity (c). Among them, the discharge exponent changes significantly with a and α. (3) Vortex-retaining PDIE exhibited a lower emitter discharge exponent versus vortex-removed versions. However, vortices increase discharge rate and reduce energy consumption of PDIE. After optimization, the emitter discharge exponent of the PDIE with the reserved vortex is 0.461, which is relatively improved by 3.556%. This study can provide a theoretical reference for the structural design of new drip irrigation emitters and functional analysis of vortices.

Improving Hydraulic Performance of Drip Irrigation Emitters Through CFD Analysis

A drip irrigation system delicately nourishes plant roots by gently delivering water drop by drop, ensuring minimal water loss due to runoff or evaporation. This method allows soil particles ample time to absorb and retain the water, promoting optimal plant hydration. To enhance the efficiency of drip irrigation, a mesmerizingly detailed 3D solid model of a drip emitter was meticulously crafted using cutting-edge SolidWorks software, revolutionizing the irrigation system's performance. CFD simulation technique is used to understanding the internal flow behavior and optimum pressure inside the in -line drip irrigation emitters. Their labyrinth structures of channels are main cause of change in flow behavior and optimum pressure in the drip irrigation emitters. Standard k-ɛ model and Enhanced wall function are used to simulate the flow behavior in labyrinth channels. Key findings are the efficiency of triangular channel is greater than the other channels (rectangular, trapezoidal and circular) based on analysis of flow rate. The value of Discharge coefficient of these channels from CFD simulation present a relationship of kCircular>kTrapezoidal>kRectangular>kTriangular. When the channel shape is smooth (like a circular channel) than the higher value of k. The efficiency of triangular channel is greater than the other channels (rectangular, trapezoidal and circular) based on analysis of flow rate. Discharge is increased by 76%, 68.42%,66.67% and 39.39% for circular channel, Trapezoidal channel, rectangular channel and Triangular Channel respectively for pressure range of 1.02m of water head to 10.2m of water head.

Characteristics of limited flow and soil water infiltration boundary of a subsurface drip irrigation emitter in silty loam soil

The accurate estimation of the infiltration boundary of a buried point source is required in the hydraulic design of a subsurface drip irrigation (SDI) system, as well as in the numerical simulation of soil water movement. In this study, an experiment was conducted to measure the variation in emitter flow rate and soil back pressure in silty loam soil. The infiltration cavity was observed, and the radius was estimated by matching the measured emitter flow rate and soil back pressure using HYDRUS-2D simulations. The relationship between the cavity radius, emitter flow rate, and soil back pressure, as affected by the soil bulk density, working pressure, and nominal emitter flow rate, are discussed. The results indicate that the infiltration cavity formed rapidly during irrigation with an irregular shape. The surface area increased as nominal emitter flow rate increased and soil bulk density increased. The variation of flow rate as a function of time had no necessary relationship with that of soil back pressure, due to the formation of the cavity. When the infiltration process became stable, higher soil bulk density resulted in increase in soil back pressure and decrease in emitter flow rate. However, the effects of working pressure and nominal emitter flow rate on soil back pressure were unclear. The emitter flow rate and back pressure, solved by an existing analytical model using estimated radius, demonstrated satisfactory agreement with the measured data, with the minimum root-mean-square error (RMSE), compared with those using a constant radius. When the infiltration boundary was taken as a constant head, the soil back pressure and cavity both significantly affected the simulated soil wetting patterns. The effect of cavity radius on the wetting front could be neglected for the constant flux boundary.

Design and hydraulic performance of bionic leaf vein‐type drip irrigation emitters

AbstractTo improve the hydraulic performance of leaf vein drip irrigation emitters, a combination of a genetic algorithm and numerical simulation was used to investigate the hydraulic characteristics of the model. The minimal flow index is used as the optimization objective to obtain the best design parameters for the flow channel structure. The results show that the leaf vein drip irrigation emitter has a flow index of 0.53, and the structural loss coefficient of the leaf vein drip irrigation emitter is 64.5–70.9 under 50 kPa working pressure, with a good energy dissipation effect. Among the design variables, the flow index (denoted as x) was influenced in the following order: the width of the unit structure f had the largest impact, followed by the vertical distance from the front baffle c, the inlet width a and the length of the unit structure h. The flow index x exhibited a positive correlation with the inlet width a, the vertical distance from the front baffle c and the length of the unit structure h, while it displayed a negative correlation with the width of the unit structure f. The correlation coefficient between the simulated and measured results was 0.994, with an average error of 2%, and the accuracy of the simulation results was high. Notably, the absence of noticeable low‐velocity vortices at the corners and confluence of the leaf vein flow channel indicated excellent resistance to blockage.

Biofilm dynamic changes in drip irrigation emitter flow channels using reclaimed water

Reusing reclaimed water through drip irrigation offers an effective way to overcome freshwater scarcity. However, biofilm accumulation in the flow channel of drip emitters is the primary obstacle. So far, biofilm development in the emitters remains largely unknown. Here, industrial computed tomography was used to quantify the emitter biofilm developments. Results showed that biofilm typically accumulated in the inlet of the emitter flow channel and decreased toward the flow direction. Biofilm was also typically accumulated in dead areas having low flow velocities, such as edge, corner, and adjacent surface zones in flow channels. The dynamics of the emitter biofilm variation mechanisms were also elucidated. Specifically, particle and nutrient transport appeared to be dominant in shaping the initial biofilm formation (i.e., 5% emitter clogging degree), resulting in biofilm abundant in the inlet of the flow channel. However, it changed the hydraulic conditions in emitter flow channels, increased local water shear stress, which made the biofilm easier to be washed away in the inlet, and caused biofilm to grow faster in the middle and outlet regions of the flow channel at 20% emitter clogging degree. At 50% clogging degree, biofilm in inlet regions grew faster again. Finally, some biofilm control approaches such as water quality management and emitter flow channel structure optimization were proposed. This study provided a better understanding of biofilm formation mechanisms in the emitter flow channels, which is critical for designing appropriate biofilm control technologies and will facilitate the reuse of reclaimed water in agricultural irrigation.

Effect and Mechanism of Micro-Nano Aeration Treatment on a Drip Irrigation Emitter Based on Groundwater

The problem of emitter clogging has become the main obstacle restricting the application and promotion of drip irrigation technology. Studying the process of emitter clogging helps improve irrigation efficiency and save water resources. A large number of researchers have tried to solve the problem of emitter clogging from many perspectives. However, the influence of micro-nano bubbles as well as generated blockage on the clogging process of drip irrigation systems is less studied. Here, the influence of aeration on emitter clogging was studied by adding micro-nano bubbles to groundwater. Four different emitters were selected. Two treatments, micro-nano aeration and non-aeration, were set up, with a total of eight sets of experiments, running for 1500 h. The degree of emitter clogging was quantitatively characterized using the discharge ratio variation (Dra). The Christiansen uniformity coefficient (Cu) and statistical uniformity coefficient (Us) were used to evaluate the influence of emitter clogging on the performance of the drip irrigation system. Compared with the non-aeration treatment group, the Dra of aerated E1–E4 decreased by 64.74%, 54.22%, 64.20%, and 94.69% in 800 h, respectively. At the same time, the Us of the aerated E1–E4 decreased by 100%, 60.05%, 92.32%, and 100%, while the Cu of aerated E1–E4 decreased by 76.64%, 53.79%, 74.11%, and 100% compared with the unaerated group. The Cu and Us of all emitters under the aeration treatment were smaller than those comparison group. As for the blockage, the main components were typical physical blockage SiO2 and chemical blockage CaCO3. Most of the blockages in the non-aeration treatment group are 5–10 μm in length, while those in the aerated treatment group were generally less than 5 μm. Aeration treatment made the blockage more broken and dense and more likely to accumulate in the flow channel, obstructing the flow of water and thus intensifying the clogging process. As a result, micro-nano aeration treatment increased the risk of emitter clogging, accelerated the development of blockage in the emitter, and disturbed the uniformity of the entire drip irrigation system. This study provides a reference idea for solving the problem of blockage in drip irrigation systems.

New anti-clogging perspective by discharging sediment from drip irrigation emitters with high-sediment loaded water

New anti-clogging perspective by discharging sediment from drip irrigation emitters with high-sediment loaded water

Assessment of water quality ions in brackish water on drip irrigation system performance applied in saline areas

Utilizing brackish water with drip irrigation technology, due to its precise water control alleviates the secondary soil salinization, and improves crop yield and quality, which offers sustainable agricultural development opportunities in saline areas. However, the complex characteristics of brackish water increase the risk of drip irrigation emitter clogging, which inhibit its promotion and adoption. It is necessary to find out the dominant water quality ions that lead to emitter clogging under multiple ion interactions when using brackish water under multiple ion coexistence conditions. Thus, the in-situ pilot research was conducted to study the emitter clogging mechanism using brackish water collected from 16 different salt-alkaline regions. A comprehensive evaluation with the consideration of 11 water quality ions on emitter clogging were conducted. Results showed that the degree of emitter clogging gradually increased in the first 40 days of irrigation, hereafter started an accelerated reduction until the days 64 of brackish water application. Spearman correlation and structural equation modelling were used to identify the main factors contribute to emitter clogging. And results indicated that calcium fouling (CF) and silica fouling (SF) were the major fouling minerals in the emitter flow channels. Ca2+, CO32-+HCO3-, pH, total hardness (TH), and zeta potential (ZP) were the key water characteristics leading to emitter clogging. These factors directly affected CF and SF, while also affecting the Mg2+, Mn2+, Cu2+, and other water quality factors which indirectly enhanced the CF and SF. Thereafter a few water quality control strategies were proposed based on emitter clogging and soil salinization mitigation. This study identified the key water quality ions that induce drip irrigation emitter clogging when using brackish water, provided solid support for solving the clogging issue, and promoted the high-efficient utilization of brackish water in saline areas.

The Study of Structural Optimization on Hydraulic Performance and Anti-Clogging Performance of Labyrinth Drip Irrigation Emitters

The core component of a properly functioning drip irrigation system is the drip irrigation emitter. Irrigation water containing impurities and sand particles can easily lead to clogging of the drip irrigation emitter, reducing the efficiency of the drip irrigation system. In this paper, orthogonal tests were used to optimize the flow channel structure, combined with the computational fluid dynamics–discrete element method (CFD-DEM) to analyze the flow index and sand particle motion characteristics. Clear water tests and short-cycle anticlogging tests were used to validate the results of the numerical simulation, and the relationship between the hydraulic performance and anti-clogging performance was revealed via linear regression. The results showed that the structural parameters of drip irrigation emitters were important factors affecting the flow index and sand movement characteristics. The order from largest to smallest was the turning angle, amount of interdental reference, flow channel depth, flow channel width, and width of the top base. The sand passage rate and the percentage decrease in velocity can be used as important indicators of anti-clogging performance, and there was a negative correlation between the two indicators. The flow channel with a 65° turning angle had the lowest flow index, and the sand passage rate can reach up to 91.48%; the reason was that the main flow region velocity was higher, the vortex region and the sand energy loss were small, which was not easy to clog. The equation for the relationship between flow index and sand passage rate was a negative correlation for drip irrigation emitters between a 65° and 75° turning angle. The drip irrigation emitter with a 65° turning angle had better hydraulic performance and anti-clogging performance.

Efficient agricultural drip irrigation inspired by fig leaf morphology

Irrigation is limited by water scarcity. Here, we show how a drip irrigation system inspired by the leaf of the fig tree Ficus religiosa (also known as the bodhi tree) can improve irrigation efficiency. The reverse curvature of the leaf regulates the convergence process of multiple water streams, while its long-tail apex allows for fast water drainage with the droplet separation centroid beyond the leaf apex. We explain why drip frequency increases after the break-up of contact line pinning at the apex tip by using scaling laws for drip volume and analyzing drainage dynamics. We build a drip irrigation emitter inspired by the bodhi leaf apex and compare the germination efficiency of wheat, cotton, and maize under different irrigation modes. These results show that the proposed bodhi-leaf-apex-mimetic (BLAM) drip irrigation can improve water saving while ensuring germination and seedling growth.

Identification of the potential use of sago midrib (Metroxylon sp.) as drip irrigation emitters for chili plants

Drip irrigation is an irrigation system that can save water by releasing a regulated amount of water and nutrients to the roots of plants using emitters. The use of emitters is one of the additional costs in the use of drip irrigation systems. Estimating the potential of fronds as emitters are done by measuring saturated hydraulic conductivity. The method used is falling head to determine the ability of emitter material made from sago fronds to pass water that can be used to meet the water needs of chili plants. The results showed that the average hydraulic conductivity value at the end sample was higher than the middle and base samples. The hydraulic conductivity values of the tip, middle and base are 0.0077 (m/s), 0.0022 (m/s), and 0.0020 (m/s), respectively. So that the tip-sample can be used as a drip irrigation emitter. The discharge produced by the emitters of tip samples 1 and 2 amounted to 1.252 and 1.424 l/day. Based on this discharge, the number of droppers for each phase of chili plant growth using sago frond emitters, namely at the base and center, requires two emitters in months 3 and 4. Meanwhile, the end frond emitter only requires two emitters in month three, and in other growth phases only requires one emitter.

Structure design and hydraulic performance analysis of drip emitters based on vortex energy dissipation

AbstractThe centre of the vortex within the drip irrigation emitter easily forms a low‐speed or zero‐velocity zone, which easily causes sediment deposition and blocks the narrow channel of the emitter. To solve this problem, a funnel‐shaped drip irrigation emitter was designed and optimized. Numerical simulations and field tests were conducted to compare and analyse the flow index, energy dissipation coefficient and relative energy dissipation ratio of the emitter. The results showed: (1) When the incident angle (θ) of the diversion channel increased from 0 to 37.4°, the energy dissipation increased from 20% to 64%. The main way of energy dissipation in the emitter changed from impingement of water to viscous drag in the vortex. (2) Under normal pressure, the energy dissipation coefficient of the vortex energy dissipation scheme (F5) was 60% higher than that of the impingement energy dissipation scheme (F1). The flow index of F5 was lower than that of F1 in both the high‐pressure and low‐pressure regions, which was in the range of 0.433–0.466. (3) Due to the spiral flow, there was a vortex with a large axial velocity inside the conical cavity, which can effectively avoid sediment deposition in the vortex centre.

Water consumption of three ornamental species with the suction irrigation system

Objective: To evaluate water consumption in ornamental plants (geranium, gazania and petunia) in two substrates with different particle sizes (fine and coarse) of tezontle and peat moss, through a suction irrigation system, which uses porous capsules as irrigation emitters. Design/methodology/approach: The experimental design was in complete randomized blocks, with six treatments (three ornamental species and two substrates) with four repetitions (24 experimental units). The first mixture contains fine substrate (composed of tezontle with particle size less than 0.4 mm) and peat moss, in a 1:2 v/v ratio; the second mixture presents coarse substrate (composed of tezontle with particle size between 0.4-0.6 mm) and peat moss, 1:1 in v/v. Results: In water consumption, there are significant differences by ornamental species and type of substrate, where the irrigation system has the ability to self-regulate. The highest water consumption was in petunia in the coarse substrate (which has a higher proportion of peat moss in its composition). Limitations on study/implications: With use in protected agriculture, rural and urban orchards, gardens, walls and green roofs and research purposes. Findings/Conclusions: The suction irrigation system through porous capsules has the capacity to continuously supply the water demanded by the plant-substrate-atmosphere system.

Analysis of internal flow characteristics and determination of the core structural parameters of a stellate labyrinth channel irrigation emitter

The hydraulic and anti-clogging performance of irrigation emitters are mainly governed by the internal flow characteristics in the flow channel. Computational fluid dynamics (CFD) and experiments were used to analyse internal flow characteristics and determine the key structural parameters of a stellate labyrinth channel irrigation emitter. Through experimental verification, the realisable k-ε model provided the best results for simulating the flow field. Five structural parameters of stellate labyrinth channel emitter were selected to study the influence on the flow characteristics inside the flow channel comprehensively. The velocity fields and profiles are presented along the stellate labyrinth channel. Turbulence properties and turbulent kinetic energy of flow inside the stellate labyrinth channel are analysed and discussed. The vortex zones consume energy and promote the deposition of particles. The swirling motion zone in stellate labyrinth channel emitter flow channel must be described to analyse flow characteristics. The advanced Q-criterion method was applied to identify and characterise the vortex zones in the stellate labyrinth flow channel. Through analysis results of the influence of different structural parameters on velocity fields, turbulence properties, and swirl characteristics, it was shown that a, r, h, and θ are main structural parameters that affect the flow characteristics in stellate labyrinth channel irrigation emitter. The results of this study provide references for the design theory of the new types of flow channel emitter.

Mechanism Analysis of the Influence of Structural Parameters on the Hydraulic Performance of the Novel Y-Shaped Emitter

As a key component of a drip irrigation system, the performance of drip irrigation emitters is determined by the flow channel structures and parameters. In this paper, a novel Y-shaped labyrinth-channel emitter was proposed, and the influence of the hydraulic performance was researched under different waist-arc angles (α) and ratios of crown height to chord length (a:b). The flow characteristics and energy dissipation mechanisms of water in the emitter were analyzed by using fluid dynamics software. The analysis showed that, keeping the ratio of crown height to chord length unchanged and with an increase in the waist-arc angle from 90° to 180°, the pressure-drop ratio before and after the water flow through the vortex area increased, and the hydraulic performance of the emitter was improved, specifically: the design flow could be reduced by 6.02–26.7%, and the slope of the curve could be reduced by 9.83–28.1%. The smaller the ratio of crown height to chord length, the weaker the influence of waist-arc angle was on the design flow and hydraulic performance. Keeping the waist-arc angle unchanged, there was a decrease in the ratio of crown height to chord length from 6:30 to 1:30, the vortex strength inside the emitter channel increased, and the hydraulic performance was improved: the design flow could be reduced by 7.56–23.5%, and the slope of the curve could be reduced by 5.43–20.5%. The bigger the waist-arc angle, the weaker the influence of the ratio of crown height to chord length was on the design flow and the hydraulic performance, even to the point of having no effect. When the Y-shaped emitter was close to the pressure-flow curve slope of the commonly-used triangular-channel emitter, the hydraulic performance of the two was similar, and the former could increase the channel width by 25%, as compared to the latter, or shorten the channel length by 44.3%. The results showed that the Y-shaped emitter had better hydraulic performance compared with the triangular-flow-channel emitter commonly used today. Therefore, the Y-shaped emitter has broad application prospects in water-saving irrigation.