Search Results (458)

Single-stage submersible pumps have widespread applications in industry. A special casing used to efficiently cool an electric motor with pumped liquid in such pumps leads to lower efficiency. This factor negatively affects the mass and dimension parameters of pump units. The efficiency can be essentially increased through impeller and casing optimization. When used in pumps, such parts with complex geometry can be manufactured in small bulk at a low price and in a short time using AM methods with different technologies and materials. Therefore, the objective of this research was to design a numerical optimization methodology to improve pump unit efficiency and to compare experimental characteristics during AM of impellers and vaned diffusers from non-metallic and metallic materials for the original and optimized flow passage. This article examined the impact of the vaned diffusers on the flow structure in the casing. The first optimization stage included studying the correlation between the input parameters and the objective function. The parameters that had the greatest impact on the hydraulic efficiency of the pump were revealed. The second optimization stage included studying the effect of the number of calculation points on the objective function using the LHS method. The global maximum of the pump's hydraulic efficiency was determined. The third optimization stage included studying direct methods for searching for the local maximum of the objective function. The best calculation point with the highest hydraulic efficiency for the pump was revealed. Recommendations regarding 3D printing for BJ and FDM technologies for AM of impellers and vaned diffusers were provided. The results of these studies revealed that velocity and flow swirl reduction in the casing increased the experimental efficiency of the pump unit by 5% at the nominal flow rate. The CFD characteristics are consistent with the experimental data. The experimental characteristics also revealed good correlation. Full article

Vegetation distribution is important for regulating overland-flow hydraulics and reducing hydraulic erosion potential on slopes. However, quantitative procedures for determining the maximum admissible spacing of multi-row vegetation under specified soil and design rainfall conditions remain limited. This study combined fixed-bed flume experiments with a theoretical hydraulic model to determine the lateral and downslope vegetation spacings required to maintain the predicted overland-flow velocity below the critical velocity for soil-particle initiation. A total of 120 runoff tests were conducted at a slope gradient of 15° under eight flow discharges (0.3–1.0 L/s) and three vegetation configurations: single-row vegetation with varying lateral spacing b, multi-row vegetation with varying b at d = 0.030 m, and multi-row vegetation with varying downslope spacing d at b = 0.010 m. Flow depth and discharge were measured, and the cross-sectional mean velocity was calculated to evaluate the Reynolds number Re, Froude number Fr, and local resistance coefficient ξ. The measured Re and Fr ranged from 475 to 1770 and from 0.83 to 2.06, respectively, indicating laminar-to-transitional regimes based on Re and predominantly supercritical flow states based on Fr, with limited subcritical and critical cases. Increasing b, d, or Q generally reduced ξ, whereas multi-row vegetation produced greater flow resistance than single-row vegetation. At each Q level, the ξ–b and ξ–d relationships followed power functions with R² ≥ 0.73. An improved local resistance formulation incorporating b, d, Re, and Fr was developed and evaluated using 129 measured data points, yielding R² values of 0.77–0.90. The proposed model was further combined with SCS-CN runoff estimates and a critical initiation velocity criterion for five soil types characterized by mean particle diameter and particle density and five 1-h design rainfall depths of 25–125 mm. Model-derived vegetation-spacing estimates were obtained for 18 of the 25 soil–rainfall scenarios, and denser vegetation distributions were generally required as the design rainfall depth increased. These results provide experimentally informed, model-based guidance for estimating multi-row vegetation spacing under specified soil and rainfall conditions. The proposed relationships and spacing estimates are condition-specific to the fixed-bed experiments with artificial emergent vegetation at a slope gradient of 15° and to the investigated hydraulic and geometric ranges. They should not be interpreted as universal design criteria or direct predictions of field soil erosion; application beyond these conditions requires further calibration and validation. Full article

Rapid urbanization has intensified two critical urban challenges: the urban heat island effect and stormwater runoff. This study evaluates the pilot-level field performance of a low-tortuosity permeable pavement (LTPP) system in potentially contributing to improved thermal regulation and hydraulic functionality. The system comprises a reduced-tortuosity upper block incorporated with bottom ash (BA) as a recycled fine aggregate and an underlying storage unit connected through an interlocking configuration, enabling direct infiltration while reducing clogging susceptibility and improving resistance to settlement and displacement. Field tests included thermal imaging, water-spraying infiltration-storage and vehicle-loading observations, and theoretical storage analysis. Initially, conventional permeable pavement (PP) dry surface temperature was measured at 44.2 °C, whereas the LTPP system already exhibited a lower temperature of 42.4 °C. During the evaporative stage after wetting, the LTPP system showed a lower temperature recovery rate, with a 2.91% increase between 90 and 120 min compared with 3.60% for conventional permeable pavement, indicating improved surface-temperature regulation. The storage calculations approximated that the LTPP system could theoretically buffer the simulated 15.63 mm/h rainfall by 6.65 to 7.32 h. It was also determined using historical rainfall data that the LTPP system, especially when provided with an outlet or drainage system, could effectively accommodate short- to medium-duration rainfall. Water-spraying tests confirmed rapid infiltration and subsurface storage, while vehicle-loading observations showed no noticeable displacement or settlement. These findings highlight the potential of a multifunctional permeable pavement design strategy that combines low-tortuosity flow paths, functional recycled aggregate selection, and subsurface storage for surface-temperature regulation and stormwater management. Full article

Stable drainage of coalbed methane wells is essential for reducing reservoir pressure and promoting methane desorption. However, coal fines carried by produced water tend to accumulate and deposit within the standing valves of drainage pumps. To address this common problem, this study investigates the transport characteristics of coal fines within the standing valve during the liquid-dominated water-pumping stage of the plunger upstroke, with the standing valve fully open. Theoretical calculations, numerical simulations, and settling experiments were conducted for three coal fines size fractions of 60–100, 100–200, and 200–400 mesh to validate the model’s predictive capability for coal fines motion. The results show that the RNG k–ε model has the lowest mean absolute relative error, at 14.50%. A solid–liquid two-phase flow model was employed to comparatively analyze five valve seat cone angles ranging from 105° to 165° and representative inlet velocities of 0.1–0.4 m/s. The results indicate that the mixture within the standing valve accelerates markedly while passing through the narrow clearance between the valve ball and the valve seat and then decelerates in the region above the valve ball. The region above the valve ball and the valve seat transition region are the primary locations of instantaneous coal fines enrichment. Increasing the inlet velocity generally enhances coal fines transport capacity and reduces the local maximum solid-phase volume fraction. Larger coal fines particles exhibit more pronounced inertial deviation and a higher degree of local enrichment, whereas smaller particles show stronger flow-following behavior and a more dispersed spatial distribution. The results further indicate that, within the investigated structural range, the 150° valve seat cone angle provides the best overall balance between coal fines transport capacity and hydraulic resistance. Ultimately, the findings provide a theoretical foundation and methodological reference for understanding the anti-clogging mechanisms of CBM pump standing valves, optimizing structural parameters, and guiding the blockage-resistant design of downhole flow components. Full article

To improve the energy conversion performance and long-term structural stability of stay vane mixed-flow chemical pumps used for industrial residual pressure recovery, this paper establishes a coupled numerical framework of computational fluid dynamics (CFD) and finite element structural analysis (FEA). The internal flow evolution, radial hydraulic excitation, transient pressure oscillation and impeller mechanical bearing capacity are systematically investigated under three typical flow states: partial load 0.7 Q_d, design condition 1.0 Q_d and overload 1.2 Q_d. The results show that the flow inside the pump is smooth and there is no obvious backflow or separation under the rated working condition, and the energy conversion efficiency is the best. When operating under partial discharge, boundary layer separation and recirculating secondary vortices easily emerge inside the pump passage, which drastically elevates hydraulic energy dissipation. Meanwhile, operating load exerts a remarkable influence on the impeller’s radial hydraulic load and transient pressure oscillation intensity. The radial force and the pressure pulsation amplitude at the impeller outlet are the largest under the small flow condition, and the force is the most stable under the rated working condition. Blade passing frequency dominates the frequency components of transient pressure fluctuations. The maximum von-Mises stress on the impeller concentrates at the filet where blade roots connect with the hub, and this peak value hits 86.3 MPa under partial-load low-flow operating status. Calculated stress values for all three flow rates satisfy the structural safety criteria. The outcomes of this numerical investigation can offer reliable technical support for hydraulic performance optimization and structural dimension design of this type of mixed-flow chemical pump. Full article

The weir–flume combination facility is a type of river flow-measurement structure consisting of a flow weir and a Crump weir, designed to integrate flow measurement and upstream backwater regulation, while incorporating a central flume intended to provide a potential passage for aquatic organisms. This study proposes a novel combined weir–flume structure and systematically validates its hydraulic performance through integrated physical experimentation and high-fidelity numerical simulation. Laboratory tests across a flow range of 5–79 L/s revealed longitudinal water surface profiles and Froude number (Fr) distributions. The study findings show that: (1) As the flow increases, the flow regime of the combination facility transitions from flume flow to weir flow, with the critical transition point at a relative water depth of 0.885. (2) The RNG k-ε turbulence model in Flow-3D software (v11.2, Flow Science, Inc., Santa Fe, NM, USA) effectively simulates the flow movement in the weir–flume combination facility, with water depth simulation results closely matching the measured values, and the maximum relative error not exceeding 5%. (3) The Fr and flow velocity in the weir–flume combination facility first increase and then decrease along the length, forming a large, thin water layer area downstream of the facility, where both Fr and flow velocity reach their maximum values. (4) Flow measurement formulas for flume flow and weir flow are obtained through data fitting, with relative errors between the calculated values and measured flow rates being less than 3%. The present study focuses on the hydraulic performance and flow measurement capability of the proposed facility. Although the structural configuration is intended to facilitate ecological passage, its ecological effectiveness was not evaluated and requires further investigation in future studies. Full article

With the increasing construction of ultra-long tunnels, complex and highly variable geological conditions along tunnel alignments pose major challenges to geological investigation, design, and construction. Conventional vertical drilling mainly provides discrete vertical geological profiles and is limited in its ability to continuously characterize lithological variations, fracture zones, and groundwater conditions along the tunnel axis. To overcome this limitation, this study proposes an integrated investigation approach based on horizontal directional drilling (HDD) for continuous along-axis geological exploration. Using the Tianshan Shengli Tunnel as the geological setting, the technical advantages of HDD for tunnel investigation—including ultra-long reach, ultra-high accuracy, high penetration rate, and strong adaptability—are first summarized. An integrated investigation method is then developed by combining HDD with targeted borehole coring, hydraulic fracturing, comprehensive borehole logging, and borehole TV imaging. A 2271 m long investigation borehole was drilled along the tunnel axis from the portal section. As a result, precise directional control limited the maximum deviation between the HDD borehole trajectory and the tunnel axis to only 6.32 m. Meanwhile, the lag distance between cuttings was determined through theoretical calculations to reconstruct the true borehole positions corresponding to the collected cuttings. Based on XRD mineralogical analysis, macroscopic observations, and preliminary investigation results, the lithology of the tunnel surrounding rock was delineated with high resolution. In addition, daily borehole inflow was monitored, and tunnel inflow during construction was predicted using the groundwater dynamics method and an empirical railway relationship, yielding an expected normal inflow of 4016.6 m³/d and a maximum inflow of 12,049.8 m³/d; furthermore, borehole TV footage was used to accurately locate inflow points and intervals with well-developed joints and fractures within the surrounding rock. Highlights This study proposes an HDD–downhole geophysics method for tunnel investigation, classifies surrounding-rock lithology from cuttings and cores, and predicts tunnel construction inflow from HDD borehole inflow monitoring data. Full article

This study numerically investigates the thermal–hydraulic performance of sharp-nose tube profiles for heat exchanger applications. Six geometries, including rounded and sharp-nose tubes with angles ranging from 20° to 45°, were analyzed at inlet velocities of 4 m/s and 12 m/s (Re = 7895–23,685). A thermal–hydraulic performance metric was used to evaluate the proposed designs against a drop-shaped tube. The results indicate that sharp-nose and double-nose profiles exhibit enhanced performance by 4–25% compared to the drop-shaped tube. The optimal configuration with a nose angle of $\theta =25°$ achieves the highest improvement in the thermal–hydraulic performance metric by 25.3% compared to the drop-shaped tube at Re = 7895. At lower Reynolds numbers, all sharp-nose configurations outperform the drop-shaped geometry, while performance converges at higher angles due to geometric similarity. The findings indicate that values calculated by employing the area-weighted average skin friction coefficient $\overline{C_f}$ and the associated flow separation behavior play a central role in determining the thermal–hydraulic performance of the tube profiles. These findings highlight the potential of sharp-nose geometries for heat exchanger performance enhancement. Full article

Lost circulation of wellbore fluids within fissured zones constitutes a primary factor contributing to increased non-productive time (NPT) and restricted rate of penetration (ROP). Conventional gel-based lost circulation materials (LCMs) inherently suffer from a tradeoff between pumpability and in situ fracture retention, and they lack a design methodology quantitatively correlated with drilling engineering parameters. In this study, a shear-responsive gel with a dual physically crosslinked network—combining hydrophobic association and Fe³⁺-mediated ionic coordination—was prepared through a single-step water-based radical polymerization process, utilizing commercially available monomers. By systematically tuning the hydrophobic monomer and Fe³⁺ contents, the gel’s fracture-sealing efficacy, autogenous healing ability, and shear rheological characteristics were evaluated, establishing a quantitative correlation between the critical shear rate and drilling parameters. The empirical data demonstrate that with an increase in the hydrophobic monomer dosage from 0.4 wt% to 1.2 wt%, the critical shear rate decreases from 22.5 s⁻¹ to 8.6 s⁻¹, exhibiting an exponential decay relationship. The optimized formulation, G0.8F0.5, demonstrates a low initial viscosity of 245 mPa·s under high shear conditions, which surges to 6180 mPa·s at a shear rate of 14.2 s⁻¹, achieving a thickening factor of 29.4. Upon incubation at 80 °C for a duration of 12 h, the formulated gel restores 94.9% of its mechanical tensile strength and 96.3% of its fracture strain, whereas the Fe³⁺-free control sample fails to heal. In dynamic plugging tests using a 3 mm fracture plate, G0.8F0.5 achieves a breakthrough pressure of 12.8 MPa with a minimal fluid loss of 98 mL. The LCM forms a monolithic gel block positioned at the middle-to-rear section of the fracture, outperforming conventional gel counterparts. Drilling hydraulics simulations reveal that deploying this gel reduces the annular equivalent circulating density (ECD) by 0.06 g/cm³. Furthermore, under idealized conditions, this approach is calculated to enhance the ROP by approximately 26%. The proposed molecular design of a shear-responsive, dual physically crosslinked network provides a viable technical pathway for quantitatively tailoring the shear-responsive properties of while-drilling LCMs. Full article

To address the rockburst hazard caused by overhanging hard roofs and difficult caving during the initial mining period of thick coal seam fully mechanized working faces, this study takes the N4202 fully mechanized top coal caving working face of the Santunzi Coal Mine as the field engineering background. The mined No. 4-1 coal seam has an average thickness of 9.46 m, and its overlying hard roof is composed of medium sandstone and siltstone. A total of 39 hydraulic fracturing boreholes, including type A, type B, type C1/C2, and fan-shaped holes, were deployed, with a designed fracturing depth of 19 m. Three testing means, including a CXK12(B) borehole imaging instrument, a KJ1222 microseismic monitoring system, and on-site roof caving observations, were adopted to comprehensively evaluate the field performance of roof hydraulic fracturing, and the rockburst prevention mechanism was analyzed. The field test results indicate that dense and well-connected fractures are formed after fracturing, with more than 8 fractures per single borehole and a fracture aperture of 0.8–2.2 mm, and the connectivity rate between adjacent fracturing boreholes reaches 92.3%. The initial mining top caving step distance of the working face is reduced to 13.2 m, while the theoretical calculated values are 10 m for the immediate roof and 15.6 m for the main roof. The roof gradually collapses, and the mining pressure is alleviated. During fracturing, the frequency and energy of microseismic events increase by 285% and 230%, respectively, compared to the state before fracturing. In the subsequent mining process, the maximum microseismic energy is only 4.56 kJ, which is far lower than the rockburst critical energy threshold (20 kJ) of this mine. Therefore, no rockburst hazard occurs in the working face. These research findings can provide a practical technical reference for rockburst prevention using hard roof hydraulic fracturing in similar thick coal seam fully mechanized mining faces. Full article

With the large-scale development of renewable energy such as wind, solar and ocean energy, the demand for energy storage is more urgent. Pumped hydro energy storage (PHES) is one of the fundamental solutions to the problem of intermittent supply of renewable energy. The large-capacity/low-head pumped hydro energy storage (LL-PHES) system with the use of tubular pump turbine is a beneficial extension of traditional PHES systems owing to large flow rate and cheaper civil structures. However, the continuous competition between the “static water pressure difference caused by gravity” and the “pressure increase caused by accelerated impeller rotation” leads to prominent instability in the start-up process of the LL-PHES system under pump conditions. An explicit coupling algorithm is proposed for analyzing the transient characteristics in the start-up process of the LL-PHES system under pump conditions. This algorithm is based on the idea of dimensional transformation, and performs 3D flow calculations and 2D rigid body dynamics equation solution in the pump domain and the flap gate domain, respectively. This algorithm avoids the problems of high computational cost and poor convergence that exist in existing fully three-dimensional coupling algorithms and ensures the efficiency of transient hydraulic characteristic calculation. A comprehensive analysis of the transient characteristics of the LL-PHES system during pump start-up process is conducted using the proposed new algorithm. The entire process of the increase in rotational speed, valve opening, flow rate, and the continuous evolution of blade surface pressure during the start-up process is quantitatively described. The amplitude and spectral characteristics of the alternating pressure on multiple blades are clarified. The evolution law of blade load during the stage of severe pressure fluctuations during the start-up process is explained. The load distribution characteristics of “high in the leading and trailing edge areas and low in the middle” in the blade stream direction is presented. The research results have a direct guiding role in improving the hydraulic design and enhancing the operational stability of LL-PHES systems. Full article

Anaerobic digestion is a viable pathway to mitigate environmental impacts from swine manure in tropical regions while contributing to circular economy strategies. However, no standardized or integrated framework currently exists that simultaneously quantifies the closure of energy, material, carbon, nutrient, and water loops at the farm scale. This research presents the techno-economic design and environmental assessment of a covered, mechanically agitated lagoon biodigester for a 10,000-head swine fattening module located in Matanzas, Cuba. The system is sized by integrating hydraulic, thermal, and structural parameters, and its economic viability is assessed through Net Present Value (NPV = $1.09 million), Internal Rate of Return (IRR = 32%), and a payback period of approximately three years. A comparative screening-level life cycle assessment shows that biogas-based electricity generation substantially reduces impacts on climate change, air quality, and fossil fuel scarcity compared with conventional diesel-based generation, with trade-offs in eutrophication and ecotoxicity. As a key methodological contribution, five quantitative circular economy indicators are proposed and calculated: the Energy Self-Sufficiency Ratio (ESSR = 1.71), the Waste Valorization Index (WVI = 0.91), the Decarbonization Index (DCI = 6.7), the Fertilizer Substitution Rate (FSR = 16.3 t N year⁻¹), and the Water Closure Factor (WCF = 1.30). These indicators show that the system achieves a 71% net energy surplus, valorizes over 90% of the input mass, avoids 6.7 times more emissions than it generates, replaces synthetic fertilizers, and returns more water than it consumes. The findings provide quantitative evidence that the convergence of mesophilic operation without auxiliary heating, high carbon intensity of the power grid, and availability of agricultural land enhances circularity performance in tropical covered lagoon bioreactors, and the proposed integrated indicator framework, aligned with ISO 59020:2024, provides a reproducible and transferable methodological basis for the comparative assessment of anaerobic digestion systems for livestock waste. Full article

This study analyzes the scouring characteristics of the Mahakam River section to support bridge design and safety assessments. Using a 100-year return period, the design rainfall was determined to be 1246 mm via the Log Pearson III method, resulting in a peak design flood discharge (Q₁₀₀) of 77,984 m³/s. Hydraulic analysis using a rating curve indicates a flood water level elevation of 32.578 m from the riverbed. Scouring calculations, including construction and stream scouring, were performed using Laursen’s and empirical methods. The results show a total scouring depth of 4.8 cm/year, primarily driven by stream scouring, as construction scouring was zero under current existing conditions. These findings emphasize the necessity of bank protection, such as gabions, to mitigate erosion risks for future infrastructure. Full article

Water shortage severely restricts agricultural output in arid and semi-arid regions, rendering improved irrigation management approaches necessary. This study assessed the hydraulic behavior of furrow irrigation in non-vegetated clay loam soil, investigating the effects of different land slopes (LS) 0, 0.05, and 0.15% and furrow length (FL) 50 and 75 m. In order to do this, field tests were conducted on a privately held farm in Banha, Qalyubia Governorate, Egypt, in March 2024. The experiment utilized a split-plot design with three repetitions, and laser-based land smoothing was used to establish the desired slopes accurately. Key hydraulic variables, namely advance time, recession time, infiltration rate, application efficiency (AE), deep percolation (DP), and distribution uniformity (DU), were recorded and calculated. The field data collected were used to calibrate and validate the WinSRFR model version 5.1.1, and its predictive ability was assessed using the coefficient of determination, root mean square error, Nash–Sutcliffe efficiency, and percent bias. The results showed that shorter FL 50 m paired with steeper gradients (0.15%) achieved better hydraulic outcomes than longer ones (75 m) with gentler slopes. Statistical analysis demonstrated that furrow length exerted a highly significant influence on all hydraulic parameters (p < 0.001). Ground slope also demonstrated a statistically meaningful influence (p < 0.05 to p < 0.01) for selected performance indicators, and the combination of LS and FL was also significant (p < 0.05). The most effective configuration, a 50 m FL paired with a 0.15% LS, yielded the highest DU (90%) and AE (87%) and the smallest DP (6%). The WinSRFR model showed outstanding accuracy in estimating advance times (R² > 0.99, RMSE < 0.55 min) and infiltration depths (R² > 0.98, RMSE < 1.3 mm), and reasonable performance for recession times (R² > 0.87, RMSE < 5.4 min). Consequently, the validated model can be confidently used to design and manage furrow irrigation in clay loam soils. These findings are anticipated to promote sustainable water consumption in farming and provide valuable input for water management policy-making. Full article

This study evaluates the technical feasibility of an autonomous photovoltaic pumping system for agricultural use in isolated communities, using a representative region of the Mixteca Poblana, Mexico, as a case study. A reference sizing methodology reported in the literature was adopted for the sizing of isolated systems, and subsequently enhanced through a structured methodological extension, applied in the final stage of the design, focused on the technical validation and commercial selection of system components. The base framework incorporates site characterization and crop selection criteria. Subsequent stages define the hydraulic and electrical design requirements for the extension of the methodology, such as the calculation of water demand, the determination of pump power, and the estimation of energy requirements. These parameters enable the integrated correlation between hydraulic demand and electrical system constraints in the selection of the main system components, including the pump, photovoltaic array, battery storage system, water storage tank, and inverter. The technical robustness of the combined approach was validated through a simulation performed using specialized solar pumping software, confirming the operational feasibility and replication potential in rural communities with similar conditions. Full article