Search Results (40)

Long-term operation of drip emitters under sediment-laden water conditions readily induces particle deposition and clogging, leading to discharge reduction and deterioration of irrigation uniformity. To clarify the temporal evolution and spatial distribution of clogging and to support structure-oriented anti-clogging improvement, three integrated drip tape emitters with different labyrinth-channel geometries were tested at sediment concentrations of 1, 2, and 3 g·L⁻¹ under a constant pressure of 100 kPa. The average relative discharge ratio (Dra) and Christiansen’s uniformity coefficient (CU) were continuously monitored, and cross-sectional observation and numerical simulation were combined to identify dominant deposition hotspot regions within the labyrinth channel. The results showed that increasing sediment concentration significantly accelerated clogging development and shortened operating lifetime. At 1 g·L⁻¹, the times required for the three emitter types to reach the clogging criterion of Dra < 75% were 120, 81, and 107 h, respectively, whereas at 3 g·L⁻¹ these values decreased to 39, 42, and 39 h. CU continuously declined with operating time and, in some treatments, responded earlier than Dra to system deterioration. Sediment deposition was mainly concentrated in the inlet section and bend regions, indicating that these locations were the dominant hotspots for clogging initiation and propagation. These findings demonstrate that clogging in drip emitters is jointly regulated by sediment load and labyrinth-channel geometry, and that hotspot-based structural optimization provides an effective basis for improving anti-clogging performance under sediment-laden water conditions. Full article

To address persistent problems such as clogging, high digging resistance, incomplete soil removal, and severe pod loss during the operation of shovel-chain peanut harvesters, a hybrid excavation approach was developed based on an in-depth analysis of the mechanical interaction between the peanut plant–soil complex (hereafter referred to as the “complex”) and the harvesting mechanism. The proposed approach integrates vertical and horizontal excavation directions to enhance soil fragmentation and reduce operational resistance. A progressive soil disintegration process was introduced, in which the complex undergoes lateral and longitudinal compression-bending deformation during movement. A driven soil–plant separation scheme was implemented through coordinated operation of upper conveying and lower combing–lifting mechanisms, promoting efficient and continuous material flow. A resistance-reducing digging device consisting of opposing round plow blades and horizontally sliding digging shovels was designed to minimize excavation resistance and soil adhesion. Meanwhile, an anti-clogging separation mechanism, integrating squeezing and feeding rollers and harrow-chain, was developed to improve soil removal and pod separation. Key structural and operational parameters—such as the chain-to-machine speed ratio, tooth-to-chain rotation speed ratio, harrow-tooth spacing ratio, and pushing-tooth transmission ratio—were optimized through theoretical analysis and prototyping. The final design also refined the number of pushing-tooth rows, squeezing and feeding roller geometry, conveying-tooth radius, and the configuration and distribution of rake and stick-tooth shafts. Field experiments were conducted using the developed prototype under sandy loam conditions (11–15% moisture content) with Yu Hua 22 peanut plants (35–40 cm height, 70 cm ridge spacing, 30 cm narrow-row spacing) at a working speed of 1.5–1.6 km·h⁻¹. Results demonstrated that the prototype achieved average ground pod loss, buried pod, and soil carryover rates of 1.13%, 0.95%, and 7.87%, respectively. The entire operation proceeded smoothly without clogging, and continuous conveying of peanut plants was maintained. These findings confirm that the proposed combined excavation and separation system meets and in some respects exceeds the performance requirements for efficient peanut harvesting under typical field conditions. Full article

In the treatment of soda-residue-stabilized soil with high water content using drainage boards with vacuum preloading, the boards often prone to clogging and bending under lateral pressure, reducing their hydraulic conductivity and affecting the soil reinforcement. In this study, the structure of the standard plastic drainage board (filter membrane + filter core) was improved, and three types of new anti-clogging plastic drainage boards with different structures were developed (Type X: geotextile + filter core, Type Y: geotextile + wire mesh + filter core, Type Z: geotextile + filter membrane + filter core). Permeability tests were subsequently used to determine the optimal structure. In-lab vertical draining tests with vacuum preloading were carried out on the selected model to study the change in water content, vacuum pressure, surface settlement, vane shear strength, and pore water pressure of soil with drainage board insertion depth, providing a reference for the application of new anti-clogging drainage boards in engineering. The results showed that: (1) the type Y anti-clogging plastic drainage board (geotextile + wire mesh + filter core) exhibits the most balanced performance in terms of permeability, anti-clogging ability, tensile strength and bending strength and is suitable for vacuum preloading of soda residue with high water content; (2) the mechanical properties and anti-clogging performance of drainage boards are highly dependent on their structural configuration. Introducing a wire mesh between the filter core and the geotextile significantly enhances the tensile and bending strength of the drainage board without noticeably compromising its drainage performance; (3) the insertion depth of the drainage board significantly affects drainage efficiency, vacuum transmission rate, and strength development of the soda residue. The effective reinforcement range of the drainage board is not limited to the insertion depth but also extends below the bottom of the drainage board. Full article

Tailings dam failures are often caused by seepage, posing severe threats to mine safety and downstream ecological environments. Conventional tailings stacking methods are prone to drainage blockage and slope instability under long-term seepage conditions. To address this issue, this study proposes a novel structural form that combines waste rock pillars with tailings stacking to construct a drainage system characterized by high permeability, anti-clogging capability, and load-bearing performance. A prototype-similar physical model test was conducted to systematically analyze the seepage characteristics and stability variations in the tailings dam under different dry beach lengths. In addition, numerical simulations using Geo-Studio 2022.1 (SEEP/W and SLOPE/W) were performed to verify and extend the experimental results. The findings show that the introduction of waste rock pillars forms effective preferential drainage channels, significantly reduces pore water pressure, and lowers the phreatic line within the dam body, thereby enhancing its overall stability. Compared with the conventional stacking method without waste rock pillars, the safety factor of the dam increased by 8.6–20.0% as the dry beach length extended from 70 m to 150 m, confirming the remarkable reinforcement and drainage performance of the composite structure. The study demonstrates that the proposed “high-permeability, anti-clogging, and load-bearing” waste rock pillar design not only achieves efficient reuse of waste rock resources but also provides a novel and sustainable technical approach for improving tailings dam safety through coupled physical and numerical verification. Full article

Clogging is a major constraint to the agricultural reuse of produced water; however, ultra-low-frequency dynamic electronic pulses (EPs) can help control biofouling in drip emitters. This study aimed to evaluate the reduction in clogging in non-self-compensating emitters applying onshore oil-and-gas-produced water treated with EP. Three experimental benches were assembled using drip irrigation units supplied with different water sources: water supply (WS), produced water with EP (OPW + EP), and produced water without treatment (OPW). Hydraulic performance was monitored every 40 h for 400 h using average flow rate variation (AFVR), flow variation coefficient (FVC), and distribution uniformity (UD) indices. Data were analyzed using RT-1 analysis with Bonferroni post hoc tests. Results showed that the interaction between water sources and evaluation times significantly (p ≤ 0.01) affected the hydraulic indices. After 400 h, the indices ranked as UD and FVC: WS > OPW + EP > OPW, and AFVR: OPW + EP = WS > OPW. Although OPW presented a low risk of clogging, the application of EP mitigated the obstruction and maintained higher uniformity by reducing clogging. These findings demonstrate that ultra-low-frequency electronic pulses are an innovative anti-clogging technology and provide insights for the sustainable application of produced water. Full article

To address the issues of low permeability, clogging susceptibility, and insufficient circumferential bearing capacity of traditional drainage blind pipes behind tunnel linings in water-rich areas, this study proposes a novel curved-mesh circumferential drainage blind pipe specifically designed for such environments. First, through engineering surveys and comparative analysis, the limitations and application demands of conventional circumferential annular drainage blind pipes in highway tunnels were identified. Based on this, the key parameters of the new blind pipe—including material, wall thickness, and aperture size—were determined. Laboratory tests were then conducted to evaluate the performance of the newly developed pipe. Subsequently, the pipe was applied in a real-world tunnel project, where a construction process and an in-service blockage inspection method for circumferential drainage pipes were proposed. Field application results indicate that, compared to commonly used FH50 soft permeable pipes and F100 semi-split spring pipes, the novel curved-mesh drainage blind pipe exhibits superior circumferential load-bearing capacity, anti-clogging performance, and deformation resistance. The proposed structure provides a total permeable area exceeding 17,500 mm², three to four times larger than that of conventional drainage pipes, effectively meeting the drainage requirements behind tunnel linings in high-water-content zones. The use of four-way connectors enhanced integration with other drainage systems, and inspection of the internal conditions confirmed that the pipe remained free of clogging and deformation. Furthermore, the curved-mesh design offers better conformity with the primary support and demonstrates stronger adaptability to complex installation conditions. Full article

Emitter clogging in drip irrigation systems is a recurring issue, affecting water application uniformity and system lifespan. This study investigated the anti-clogging performance of emitters and the accumulation patterns of solid particles in dripper labyrinths with varied geometric configurations, combining laboratory experimentation and computational fluid dynamics simulations. Fifteen labyrinth models were tested, divided into two groups: (Model A) emitters with well-defined vortexes and (Model B) emitters with uniform flow. The tests were conducted with solid particle concentrations of 125 and 500 mg L⁻¹ over 200 h of operation. The results showed that none of the emitters became clogged, even under severe particle concentration conditions. However, distinct deposition patterns were observed. Emitters with vortex formation accumulated particles in low-velocity zones, especially in the first baffles of the labyrinth. In contrast, emitters with uniform flow minimized sediment buildup, maintaining high velocities throughout the channel section. Simulations confirmed that the relationship between labyrinth geometry and flow velocity directly influences particle deposition. Dripper design strategies aimed at reducing low-velocity zones in the channel could help mitigate clogging risks. The findings of this study provide valuable guidelines for developing more clogging-resistant emitters, contributing to the improvement of drip irrigation systems. Full article

The rapid expansion of urban areas has increased the prevalence of impermeable surfaces, intensifying flooding risks by disrupting natural water infiltration. Permeable pavements have emerged as a sustainable alternative, capable of reducing stormwater runoff, improving surface friction, and mitigating urban heat island effects. Nevertheless, their broader implementation is often hindered by issues such as clogging and limited mechanical strength resulting from high porosity. This study examines the design of interlocking permeable blocks utilizing ultra-high-performance concrete (UHPC) to strike a balance between enhanced drainage capacity and high structural performance. A topology optimization (TO) strategy was applied to numerically model the ideal block geometry, incorporating 105 drainage channels with a diameter of 6 mm—chosen to ensure manufacturability and structural integrity. The UHPC formulation was developed using particle packing optimization with ordinary Portland cement (OPC), silica fume, and limestone filler to reduce binder content while achieving superior strength and workability, guided by rheological assessments. Experimental tests revealed that the perforated UHPC blocks reached compressive strengths of 87.8 MPa at 7 days and 101.0 MPa at 28 days, whereas the solid UHPC blocks achieved compressive strengths of 125.8 MPa and 146.2 MPa, respectively. In contrast, commercial permeable concrete blocks reached only 28.9 MPa at 28 days. Despite a reduction of approximately 30.9% in strength due to perforations, the UHPC-105holes blocks still far exceed the 41 MPa threshold required for certain structural applications. These results highlight the mechanical superiority of the UHPC blocks and confirm their viability for structural use even with enhanced permeability features. The present research emphasizes mechanical and structural performance, while future work will address hydraulic conductivity and anticlogging behavior. Overall, the findings support the use of topology-optimized UHPC permeable blocks as a resilient solution for sustainable urban drainage systems, combining durability, strength, and environmental performance. Full article

Water scarcity in Brazil’s semi-arid region necessitates the agricultural reuse of aquaculture effluents, although emitter clogging remains a challenge. This study evaluated clogging mitigation in drip irrigation systems using liquid anti-clogging fertilizer. The experiment employed a split–split–plot scheme with three water treatments (supply water, aquaculture effluent, and effluent with liquid fertilizer) and three emitter types (ST, SL, and GA), assessing performance over 360 h. A water quality analysis at 0, 160, and 360 h complemented hydraulic evaluations of the average flow rate variation and Christiansen uniformity coefficient measured every 40 h. Energy-dispersive X-ray spectroscopy, X-ray diffractometry, and scanning electron microscopy were used to characterize biofouling. The results showed that the liquid fertilizer mitigated the clogging by biofouling in the three types of emitters, but only the ST emitter presented acceptable hydraulic performance rates. There are relationships between the anti-clogging effect of the liquid fertilizer, the structural characteristics of the emitters, and the flow velocity inside the labyrinths. The SL dripper applying only aquaculture effluent presented the highest clogging rate due to biofouling. Agricultural reuse is a strategy for the rational use of water resources that is of great relevance for arid and semi-arid regions and can insert aquaculture into the circular economy. Full article

The automatic flushing valve (AFV) enables automatic flushing of drip irrigation systems, improving their anti-clogging performance. This study focuses on a subsurface drip irrigation system (SDI) for alfalfa, selecting T20 and T70 AFVs (with designed flushing durations of 20 and 70 s, respectively) installed at the end of the dripline and a buried dripline without an AFV as a control. The aim of this study was to explore the variations in AFV hydraulic performance over two years of operation and the impact on the irrigation uniformity of SDI systems. The results revealed that the flushing duration (FD) and flushing water volume (FQ) of both T20 and T70 fluctuated over time, with an average coefficient of variation (CV) of 13.2%. The FD and FQ of the two types of AFVs are affected by the daily average temperature (T), and when T increases from 20.1 °C to 25.7 °C, the FD and FQ increased by an average of 22.6%. After 2 years of operation, the average relative flow rate (Dra) and irrigation uniformity (Cu) of the T20 and T70 SDI emitters were 93.7% and 96.8%. Both the Dra and Cu were significantly influenced by FD (p < 0.05). Compared with CK and T20, T70 significantly increased the Dra and Cu by 6.3% and 4.6%, respectively. The order of degree of clogging at different positions in the dripline was rear > middle > front for the CK and T20 treatments, whereas for T70, it was middle > front > rear. With the installation of the T70 AFV, the time required for the SDI system to reach moderate clogging (Dra = 50~80%) was extended from 3~7 years to 8~20 years, resulting in a 180% increase in operation time. The T70 AFV is recommended for use in the alfalfa SDI of this study. Full article

Developing efficient water-saving irrigation technologies that utilize high sand-laden water is an important approach to alleviating agricultural water scarcity in the Yellow River Basin. This study aims to investigate sedimentation patterns and fluid movement characteristics in drip irrigation emitters under such challenging water conditions. The dynamic changes in Dra and Cu were determined through short-period intermittent clogging tests to evaluate the anti-clogging performance of four different emitter types. The distribution and particle size composition of the deposited sediments inside the emitters were analyzed using a high-resolution electron microscope and a laser particle size analyzer. Additionally, the RNG k-ε turbulence model was used to simulate the fluid movement inside the emitters. The results showed that the B drip irrigation belt had better sediment tolerance and operational stability. The anti-clogging capacity of drip irrigation can be improved by optimizing the combination of emitter channel structure and sediment content. The fluid in the channel was divided into mainstream zone and vortex zone. Sediment particles increased in the backing-water zone and vortex center, where particles of 0.05–0.1 mm were more prone to settling due to reduced transport capacity. Energy dissipation primarily took place at the curvature of the emitter channel, and within each channel unit, gradually decreasing along the vortex flow direction, with the lowest dissipation aligning with sediment deposition zones. These findings provide a theoretical basis for mitigating clogging in high sand-laden water drip irrigation systems, offering valuable insights for improving the effective utilization of water resources in the Yellow River Basin. Full article

Accurate numerical simulation of turbulent flow within the milli-channels of drip irrigation emitters has long been a significant challenge. This paper presents a comprehensive Reynolds-Averaged Navier–Stokes (RANS) modeling-based analysis of the flow dynamics within the labyrinth milli-channel of a tooth-shaped emitter, with partial experimental validation. The objective was to assess the performances of four RANS turbulence models: RNG k-ε (RNG), Realizable k-ε (RKE), SST k-ω (SST), and baseline k-ω (BSL), alongside three near-wall treatments: scalable wall function (SWF), enhanced wall treatment (EWT), and y⁺-insensitive wall treatment (YIWT) for emitter flow analysis. The results showed that the RNG and RKE, coupled with EWT, are preferred options for predicting the flow rate—pressure loss relationship of the emitter, with relative errors of 2.08% and 1.02% in the discharge exponent and 5.66% and 7.58% in the flow rate coefficient, respectively. Although both RNG and RKE using SWF are viable for hydraulic performance prediction under high-flow rate conditions, the deviation of predicted flow rate reaches up to 25.46% under low-flow rate conditions. The SST and BSL models, which employ IYPT, captured induced vortices at channel corners; however, they underestimated emitter flow rates. Furthermore, computations using SWF failed to capture the asymptotic characteristics of flow parameters in the near-wall region, resulting in an overestimation of turbulent kinetic energy and turbulence intensity. Additionally, the magnitude of wall shear stress in the channel corners fell below the threshold required for self-cleaning, underscoring the necessity for optimizing channel structures to enhance the anti-clogging performance of the emitter. Full article

Reducing the flow rate (q) of the emitter can increase the dripline laying length and reduce the engineering investment of the drip irrigation system; however, reducing q increases the risk of emitter clogging. In this study, based on the OPFN method (Optimal Latin Hypercube Experimental Design–Parametric Modeling of Emitter–Fluid Dynamics Simulation–NSGA-II Genetic Algorithm Optimization), we selected the structural parameters of channel tooth height (E), angle (A), pitch of teeth (B), and flow channel depth (D) to construct 128 emitters. Through simulation, we obtained q, the flow index (x), and the structural resistance coefficient (Cs) under the pressure (H) ranging from 0.02 to 0.15 MPa. The results showed that the rated flow rate (q_0.1) and x values of 128 emitters range from 0.50 to 0.85 L/h and 0.461 to 0.480, respectively. Since Cs is negatively correlated with x, to obtain the combination of the flow channel structural parameters with the optimal hydraulic performance (x = min f(E, A, B, D)) and the optimal anti-clogging performance (Cs = min g(E, A, B, D)), the flow channel structural parameters are optimized by using the NSGA-II genetic algorithm to obtain the Pareto frontier solution. The optimal combinations of channel structural parameters corresponding to the q_0.1 values of 0.62, 0.71, and 0.82 L/h with x of 0.470, 0.466, and 0.463 are obtained using the weighting method. Cs values are 0.131, 0.446, and 0.619, respectively. The limit laying length of the configured emitter is 150–180 m. According to the flow field cloud diagram before and after optimization, it can be found that increasing the high-velocity area and high-turbulent-kinetic-energy area in the main stream and decreasing the low-velocity area and low-turbulent-kinetic-energy area in the tooth base and downstream face can help reduce x and Cs, and thus improve the hydraulic performance and anti-clogging performance of the small flow rate emitter. Full article

Variable flow emitters are used in subsurface drip irrigation to address challenges in soil moisture transport. This study investigates the impact of flow channel structural parameters on the hydraulic performance and anticlogging ability of emitters using computational fluid dynamics (CFD) simulations and experimental tests. The results show that the realizable k–ε turbulence model can be used to simulate the flow field inside the variable flow emitter flow channel. The nRMSE between the measured (q_m) and simulated (q) values of the flow rate is 11.23%, and the relative error between the measured (x_m) and simulated (x) values of the flow index is 4.66%, which gives a high simulation accuracy. A polar analysis shows that the tooth angle (A) has the smallest effect on the effluent flow rate at 0.1 MPa (q_0.1), x, and particle passage rate (η) of the variable flow emitter. Flow channel depth (D), tooth spacing (B), and tooth height (E) have a different order of precedence in the influence of the three indices, which are D > B > E > A, B > E > D > A and E > B > D > A, respectively. The value of η is positively correlated with the mean flow velocity (v) and the mean turbulent kinetic energy (k) in the flow channel, and η tends to increase and then decrease with the increase of x. The retention time of the particles in the flow channel is closely related to the magnitude of v and k. Three multivariate lin ear regression equations (R² = 0.883–0.995) were constructed for q_0.1, x, and η versus the flow channel structural parameters. The optimal design combination of channel structure parameters for different scenarios was determined using the scipy.optimize.minimize function in Python 3.8.0. The research results provide a reference for the optimal design of variable flow emitters. Full article

A submersible sewage pump is designed for conveying solid–liquid two-phase media containing sewage, waste, and fiber components, through its small and compact design and its excellent anti-winding and anti-clogging capabilities. In this paper, the computational fluid dynamics–discrete element method (CFD-DEM) coupling model is used to study the influence of different conveying conditions and particle parameters on the wear of the flow components in a submersible sewage pump. At the same time, the energy balance equation is used to explore the influence mechanism of different tip clearance sizes on the internal flow pattern, wear, and energy conversion mechanism of the pump. This study demonstrates that increasing the particle volume fraction decreases the inlet particle velocity and intensifies wear in critical areas. When enlarging the tip clearance thickness from 0.4 mm to 1.0 mm, the leakage vortex formation at the inlet is enhanced, leading to increased wear rates in terms of the blade and volute. Consequently, the total energy loss and turbulent kinetic energy generation increased by 3.57% and 2.25%, respectively, while the local loss coefficient in regard to the impeller channel cross-section increased significantly. The findings in this study offer essential knowledge for enhancing the performance and ensuring the stable operation of pumps under solid–liquid two-phase flow conditions. Full article