Search Results (1,585)

Understanding the role of faults in directing groundwater flow within bedrock aquifers is crucial, especially in the arid Southwestern United States, where water demand is exceptionally high. This study investigates the confined Coconino aquifer (Permian, 282–270 Ma), located between Springerville and Saint Johns, Arizona, and supplying the Springerville Generating Station. Using abundant well-pumping and water-level data, we analyzed how distinct regional geological structures, specifically the Coyote Wash fault (a steeply dipping normal fault; initially 70–30 Ma old with subsequent middle-to-late Quaternary and younger activity (<750 ka), the Cedar Mesa anticline, and the Buttes anticline, control local groundwater movement. Although the parallel Coyote Wash and Cedar Mesa structures experience similar regional stresses, model calibration yields hydraulic characteristics (hydraulic conductivity divided by barrier thickness) of 1.0 1/day for the Coyote Wash fault and 0.0001 1/day for the Cedar Mesa anticline, four orders of magnitude lower. Seismic reflection profiling reveals a disrupted zone, roughly 200 m wide, associated with the Cedar Mesa structures. Because these faults are perpendicular to the maximum horizontal stress direction, prevailing compressive forces theoretically close fracture apertures and severely restrict water flow. However, this study reveals that highly permeable regions exist where the structural damage zones of these prominent faults overlap. Ultimately, even in restrictive geological environments where ambient stresses predict sealed fractures, the overlapping damage zones of multiple intersecting faults can unexpectedly generate critical, highly permeable pathways for sustained deep groundwater flow today. Full article

Low-head, high-discharge agricultural irrigation and drainage pumping stations require efficient and stable operation under variable-flow conditions, while flow separation and wake vortices downstream of the bulb body can intensify energy dissipation and pressure pulsations. To mitigate these effects, three bulb body configurations—the original configuration, salmon-tail configuration, and grouper-tail configuration—were investigated numerically using the SST-CC model, with vortex structures, entropy production, and pressure pulsations analyzed. The results show that the bionic tails have little influence on head but improve efficiency over 0.93–1.13 $Q_{des}$, with the grouper-tail configuration providing more consistent enhancement. At 0.80 $Q_{des}$, the vortex-structure volume fraction decreases from 2.69% to 1.65–1.71%. Entropy production analysis shows that the impeller remains the main loss region, whereas the outlet channel loss contribution increases with flow rate, indicating stronger effects of wake transport and residual swirl under high-flow conditions. At 1.13 $Q_{des}$, the bionic tails reduce the overall pressure-pulsation amplitude by about 62.5%, the low-order energy proportion from 6.39% to about 1.40%, and the dynamic pressure stability index by 44.49–49.39%. In contrast, at the design condition $Q_{des}$, the DPSI increases from 0.186 for the original configuration to 0.266 and 0.323 for the salmon-tail and grouper-tail configurations, respectively, indicating deteriorated dynamic pressure stability. These findings demonstrate the strongly condition-dependent effects of bionic fish-tail geometries on energy performance and dynamic pressure stability, revealing a trade-off between hydraulic performance improvement and pressure stability rather than a uniform benefit across the entire operating range. Full article

Growing wind and photovoltaic generation increases the demand for large-scale, long-duration energy storage. Pumped hydro compressed-air energy storage (PHCAES) stores and releases energy through pressure transfer between water and compressed air, using air pressure to provide an equivalent hydraulic head and thereby reducing dependence on natural elevation while retaining hydraulic energy conversion and the potential for near-isothermal operation. This review establishes a taxonomy of hydraulically coupled compressed-air storage comprising PHCAES, liquid-piston systems, hydraulically compensated constant-pressure CAES, and hydraulic–pneumatic cascade or hybrid systems. Variable- and constant-pressure PHCAES are compared with pumped hydro energy storage (PHES) and compressed-air energy storage (CAES) in terms of efficiency, economics and environmental implications; this is followed by a critical analysis of the mechanisms governing PHCAES performance. The results show that improved siting flexibility is the principal conditional advantage of PHCAES, rather than inherently higher efficiency or lower cost. Its net performance depends on pressure–volume matching, gas–liquid heat transfer, hydraulic-machine operation, auxiliary consumption and storage infrastructure. Pressure regulation and thermal enhancement are beneficial only when their gains exceed the associated compression, throttling and auxiliary losses. The principal research gap is the lack of engineering-scale, full-cycle validation using consistent electrical, economic and lifecycle assessment boundaries, which currently prevents robust comparison with PHES and CAES. Full article

Variable speed pumped storage units (VSPSUs) offer flexible active-power regulation capability; however, during large power variations, it remains challenging to simultaneously achieve fast power tracking and effective rotor-speed regulation. To address this issue, this paper proposes a power–speed hybrid control strategy for VSPSUs in generating mode. Within a unified control framework, a weighting coefficient λ is introduced to coordinate the allocation of power and speed control objectives between the electromagnetic and hydraulic–mechanical control channels. A sensitivity analysis is further conducted for λ = 0.1–0.9 based on the dynamic performance indices of active power and rotor speed. The results show that, under the operating condition considered, the composite performance index is minimized at λ = 0.5. For an active power step from 0.4 p.u. to 0.8 p.u., compared with power-priority control, the proposed strategy effectively suppresses power oscillations, reducing the active-power overshoot from 29.88% to 0.85% and shortening the ±5% settling time from 2.829 s to 0.230 s. In addition, the proposed strategy maintains good dynamic adaptability when the water inertia time constant T_w varies by ±20%. The proposed method provides a low-complexity control solution for coordinating active-power response and rotor-speed regulation in VSPSUs. Full article

Polders are typical semi-artificial and human-dominated ecosystems widely distributed in the middle and lower reaches of the Yangtze River Basin. They serve as important sinks and sources of nitrogen (N) and phosphorus (P) in agricultural watersheds. Long-term intensive human intervention substantially alters the hydrological and biogeochemical processes of polder ecosystems, resulting in complex and uncertain effects on water quality that remain insufficiently understood. This study conducts a systematic literature review and narrative synthesis of evidence on N and P transport in polders across the middle–lower Yangtze River plain. The evidence is derived from field monitoring, plot experiments, and numerical simulations. The review focuses on the spatiotemporal patterns of nutrient variation, sink–source conversion functions of ditches and small ponds, drivers of nutrient loss, and current research bottlenecks under artificial sluice-pump regulation. The synthesized results indicate that polders exhibit a distinctive nutrient transport pattern characterized by dispersed in situ retention under conventional water management and concentrated pulse export during drainage events. Artificial sluice-pump operation drives episodic nutrient export throughout the crop growth period, imposing persistent pressure on the water quality of downstream rivers and lakes. N and P transformations are jointly controlled by natural hydrological fluctuations and human activities. Within agricultural lands of polders, fertilizers account for 73.3% of total nitrogen inputs and 87.9–93.5% of total phosphorus inputs. Crop harvesting and regulated drainage constitute the two dominant pathways for nutrient export. Hydraulic regulation prolongs water residence time in polder ditches and ponds, resulting in retention efficiencies of 52–65% for allochthonous N and P. However, seasonal flooding and waterlogging can induce sediment hypoxia and endogenous nutrient release, thereby causing secondary internal pollution and increasing the eutrophication risk of adjacent receiving water bodies. Three major research gaps are identified: insufficient long-term continuous multi-indicator monitoring data, limited model applicability for simulating human-regulated hydrology–nutrient coupling, and poorly defined critical thresholds for polder sink–source functional reversal. This regional systematic review advances the understanding of human–hydrology–nutrient coupling mechanisms in Yangtze River polder systems. It also provides targeted theoretical support for agricultural non-point source pollution mitigation and water environment management in floodplain agricultural areas. Full article

Centralized sewer networks are rarely feasible for scattered mountain villages across China. Their construction costs stay high, and uneven terrain easily triggers pipe blockages and infiltration. Most existing rural wastewater treatment devices run on fixed operating schedules. They maintain full aeration even during low water inflow, wasting electricity and destabilizing effluent quality. This study reports a full-scale summer field assessment of an integrated attached-growth biofilm reactor deployed at the sewage treatment station serving Miaodong and Miaoxi Villages, Ruyang County, Henan Province, China. The system combines hydrolysis acidification, two-stage biological contact oxidation, sedimentation, post-sedimentation polishing, and a cloud-connected monitoring and control module. The control system adjusts influent pumping, aeration, internal reflux, and sludge discharge in response to measured hydraulic and dissolved-oxygen signals. The design treatment capacity was 850 m³ d⁻¹. During the 25-day monitoring period, the packing filling ratio was 70%, dissolved oxygen was maintained at 2.0–4.0 mg L⁻¹, and water temperature was 20 ± 5 °C. Average COD removal reached 91.1%, ammonium nitrogen (NH₄⁺-N) removal reached 88.9%, total nitrogen (TN) removal reached 83.5%, and total phosphorus (TP) removal achieved 81.7%. The average unit electricity consumption was 0.195 kWh·m⁻³. Because no fixed-frequency reference operation was conducted under identical influent and environmental conditions, the specific energy-saving contribution of the adaptive control module could not be quantitatively isolated. The reported value should therefore be interpreted as system-level field performance rather than as a verified percentage reduction attributable exclusively to intelligent control. The average TP concentration after polishing was 0.59 mg L⁻¹, exceeding the 0.5 mg L⁻¹ Class A limit of GB 18918-2002. The results characterize summer operation under the investigated loading and temperature conditions and should not be extrapolated directly to year-round compliance, winter operation, or heavy-rainfall events. Full article

This paper presents a real-time browser-based platform for thermohydraulic characterization of a compact laboratory heating system, developed using the PolyVR research-grade virtual reality engine. Experimental measurements are retrieved at 1 Hz from a cloud-based database and processed via browser-native computational framework that continuously performs thermophysical modeling, hydraulic analysis and energy balance evaluation. The system calculates the rate of heat transfer (h), overall heat transfer coefficient (U), dimensionless numbers (Re, Pr, Gr, Nu), pump performance, heater efficiency and cumulative thermal energy. PolyVR provides the immersive environment in which the partial digital twin functionality is integrated alongside the browser-based thermohydraulic calculations. The whole system includes support for animations regarding flow diagrams, valve state indicators, thermal field visualization and manipulation of system elements. The system architecture is designed to work on desktops, head-mounted devices, as well as in CAVE (cave automatic virtual environment) systems with remote connection made possible via using ngrok tunnels. The experiments were separated into three categories (steady-state, dynamic and validation). Steady-state and dynamic datasets show that the browser computation with PolyVR achieves high-fidelity thermohydraulic analysis similar to that done in laboratory settings. The steady-state and transient datasets illustrate that browser-based computation provides highly accurate thermohydraulic simulation close to that of the laboratory reference computations. For all experiments performed on the platform, the deviation of measurements does not exceed ±0.5 K in temperature, ±5% in flow rate and ±1% in pressure. The energy balance is closed with a deviation of ±2–3%. Full article

Steel storage tanks are erected on site by multi-cylinder hydraulic lifting, conventionally from one power unit feeding all cylinders through a flow divider. Decentralized alternatives have not been evaluated for this task, and modularity in fluid power is rarely quantified. A ten-cylinder device was analyzed as a centralized (C1) and a modular (C3) variant with a servomotor-driven pump at each cylinder; both were decomposed into five functional modules and compared through a directed design structure matrix (DSM). External dependencies per module fell by 38.6% and mean interface complexity by 30.9%, against only 11.1% for interfaces per module: interfaces were thinned, not removed. Internal cohesion rose from 0.583 to 0.805; the total risk priority number, an ordinal expert-assigned indicator, fell from 2253 to 760. C1 was characterized from documentation and was not tested experimentally; a three-module prototype at a length scale of 0.31 was run through sixteen series: open and closed loop, both directions, four disturbance configurations. In open loop, the error left the ±2% band in every series; in closed loop, it stayed inside the band in lifting and over the last 91–92% of stroke in lowering, cutting the drift rate by one to two orders of magnitude. The structural gain corresponds to removing the hydraulic installation and the flow divider, which dominate both the open-loop drift and the failure-mode ranking; the modular device costs about 58% more. Full article

To clarify the effects of splitter blades on hydraulic performance and internal energy dissipation in a double-suction pump as turbine (PAT), full-passage CFD models of a PAT and a PAT with splitter blades were established and experimentally validated. Same-flow-rate cross-comparisons at the BEP flow rates of the configurations distinguished geometric effects from flow-rate effects. Impeller loss redistribution was analyzed using entropy generation, LEGR, TKE, and radial-flow characteristics. The splitter blades shifted the BEP flow rate from 1350 to 1708 m³/h, an increase of 26.52%, and increased the maximum efficiency from 85.61% to 87.72%. Turbulent and wall entropy generation dominated the loss, whereas direct viscous entropy generation contributed less than 1%. At the prototype BEP flow rate, the normalized volumetric entropy-generation coefficient over Regions I–O decreased by 10.31%; at the splitter-blade BEP flow rate, the reduction reached 60.71%, with Region M decreasing by 66.33% and providing the dominant absolute loss reduction. At the higher flow rate, splitter blades restricted the lateral expansion of low-velocity regions, weakened large-scale separation and continuous high-LEGR shear structures, and confined the remaining high-loss regions to blade leading edges, splitter-blade wakes, and local flow-recombination zones. These results show that splitter blades improve high-flow-rate performance by suppressing separation- and shear-related volumetric dissipation and redistributing impeller energy losses. Full article

This study presents a displacement feasibility methodology for a closed-center load-sensing hydraulic system intended for industrial forklift applications. The approach combines analytical hydraulic calculations with simulation-based verification in Automation Studio. A Perkins D3900K diesel engine (Bulgarian industrial group Balkancar) and several Danfoss H1 axial piston pump (Danfoss Power Solutions Nordborg, Denmark) displacements were evaluated under engine power limitations. Pump flow, torque demand, hydraulic power, and a power-limited pressure envelope were derived to support engine–pump matching. The results show that oversized pumps significantly reduce allowable pressure, particularly at higher engine speeds. Pump displacements of 45–60 cm³/rev provide the most balanced compromise between pressure capability and practical flow delivery. Full article

Multiphase pumps are key equipment for the efficient transport of multiphase fluids in the petroleum industry, and their transient stability under variable-speed conditions directly affects system reliability. By combining numerical simulation with experimental validation, this study systematically investigates the evolution of external characteristics, energy conversion mechanisms, and the dynamic response of the internal flow field during a 0.4 s variable-frequency speed regulation cycle at inlet gas volume fractions (IGVFs) of 10% and 20%. The numerical model was validated against experimental measurements of a four-stage multiphase pump under pure-water steady-state conditions, with deviations in head, efficiency, and power all within 5%. The results show that during acceleration, the increase in hydraulic efficiency at the lower IGVF is greater than that at the higher IGVF; once deceleration begins, IGVF has no significant effect on hydraulic efficiency. At the investigated IGVFs of 10% and 20%, a higher IGVF increases the transient sensitivity of the internal flow field to speed variation, and increasing IGVF suppresses energy conversion in the impeller. The principal novelty of this work lies in the temporal decomposition of impeller work into dynamic and static pressure components during transient speed variation, revealing that static pressure power consistently accounts for more than 50% of the total power throughout the speed regulation cycle. As rotational speed increases, dynamic pressure power rises because the circumferential velocity of the fluid increases with impeller peripheral speed, while static pressure power also increases continuously owing to the enhanced static pressure work of the blades. During deceleration, the impeller’s energy transfer capability weakens with decreasing rotational speed, and both dynamic and static pressure power decline. These findings elucidate the coupled evolution of gas–liquid two-phase flow under variable-speed conditions and provide a theoretical basis for the operational optimization and speed control of multiphase pumps. Full article

The stream of onions entering a self-propelled onion collector varies with field conditions, feeding density, and the transient lifting behavior of the onion–soil mass, whereas the collection conveyor is conventionally operated at a fixed speed, wasting hydraulic energy. This study proposes and evaluates, through field-calibrated simulation, a vision-based feedforward conveyor speed control framework that couples reel-synchronous onion counting with variable-displacement pump control. To mitigate the periodic occlusion caused by the compact dual-conveyor structure, a frame-selection method synchronized with the detected conveyor position was implemented, and a YOLOv8n detector was trained and evaluated on 314 images extracted from 32 indoor and field source videos partitioned at the source-video level. On the independent test subset, the model achieved precision, recall, and mAP@0.5 of 0.952, 0.944, and 0.959, and the proposed counting method maintained count recovery ratios above 95% across all engine speeds in 45 independent field trials, outperforming fixed-period sampling and tracking-based baselines by 6.6 and 3.8 percentage points, respectively. An AMESim model of the fixed-displacement hydraulic system was calibrated and shown to be consistent with field measurements and was then used to evaluate the variable-displacement configuration. Net conveyor-related fuel savings (engine no-load consumption subtracted) were estimated at 14.3–18.7% under the field-identified constant transmission efficiency, with conservative estimates of 11.5–16.9% when partial-displacement efficiency losses were accounted for through an anchored loss model. These results demonstrate the feasibility of vision-based feedforward conveyor speed control and its potential for energy savings in bulb-crop collection. Full article

Hydraulic transients induced by rapid changes in operating conditions represent a major challenge in the design and safe operation of offshore Firewater systems. During emergency events, such as fire pump start-up or rapid valve operations, pressure waves may propagate throughout the distribution network, generating water hammer effects capable of compromising the integrity and reliability of critical safety equipment. This study investigates the transient hydraulic response of an offshore Firewater ring-main system installed on a Floating Production Storage and Offloading (FPSO) unit using a detailed numerical model developed in PIPENET Transient. Three representative emergency operating scenarios were analysed, including fire pump start-up, deluge valve closure, and monitor valve closure. For each scenario, the hydraulic response of the original system configuration was compared with a modified pressure-protection arrangement involving relocation of the check valve immediately downstream of the fire-pump discharge flange and reduction of the pressure safety valve (PSV) set pressure from 17.5 barg to 16.5 barg. The simulations enabled the identification of critical pressure locations, evaluation of transient pressure propagation, and assessment of the effectiveness of the proposed mitigation strategy. The results demonstrate that the modified pressure-protection arrangement reduces the governing system-level pressure peaks and attenuates transient pressure oscillations under the investigated operating conditions. The proposed engineering methodology provides practical support for the design verification and optimization of offshore Firewater systems and contributes to improving the operational safety and reliability of safety-critical piping networks. Full article

Solar thermal calorimeters serve as foundational reference instruments for quantifying absorbed thermal power, evaluating optical-to-thermal conversion efficiency, and validating computational models in concentrated solar thermal (CST) research. This review synthesizes recent numerical, thermo-hydraulic, and experimental advancements, evaluating the evolution from basic single-tube configurations to high-confinement cavity calorimeters (achieving apparent absorptances $>0.99$) and flat-plate architecture enhanced with impinging jets and internal fin arrays. The selection of working fluids is examined; water accounts for approximately $87\%$ of reported implementations due to low property uncertainty, whereas synthetic oils and gaseous coolants expand operating temperature ranges at the expense of thermochemical degradation and parasitic pumping penalties. Furthermore, critical thermo-hydraulic challenges induced by extreme non-uniform heat fluxes are identified, including structural thermal bowing, parallel-channel flow maldistribution, recirculation traps, and buoyancy-driven instabilities occurring at Richardson numbers $\mathrm{Ri}\gg 10$. Metrological constraints related to solar reflection interference in non-contact thermometry and calibration drift in photometric target arrays are also critically addressed. Finally, key strategic research directions are outlined, emphasizing high-temperature advanced materials, active flow equalization, real-time multi-physics digital twins, and standardized dynamic testing metrology. Full article

Carbonates host valuable groundwater and geo-energy resources in shallow (<0.2 km below groudsurface) and deep (0.2 to 4 km) aquifers, respectively. The hydraulic conductivities of fractured carbonates are unknown at elevated depths (>0.2 km below ground level). To tackle this scenario, the hydraulic conductivity of four Mesozoic units were reviewed in the Umbria–Marche Succession (Italy) due to the large amount of literature available from geothermal exploration and earthquake forecasting. The hydraulic conductivity decreases of three-order (10³) of magnitude from 0.1 to 4 km below the groudsurface according to pumping, and tracer tests, and regional flow models. The Calcare Massiccio and Scaglia Bianca formations appear the most and less hydraulically conductive units, respectively. Seismogenic faults were classified as combined conduit–barriers due to the presence of damage zones and cores. Cores were tested in the laboratory, providing low (up to 8.0 × 10⁻⁸ m day⁻¹) hydraulic conductivities. The small-scale faults studied at shallow depths (0.2 km) can be classified as karstified conduits according to the dataset. Overall, the review showed that a summary of the hydraulic conductivities of fractured carbonates at a variety of depths find application on the sustainable management of shallow groundwater resources and multiple sectors of the geo-energy industry. Full article