Search Results (578)

The increasing energy consumption of large datacenters, with cooling systems constituting a significant portion, calls for efficient thermal management strategies. Conventional computational fluid dynamics (CFD) methods, although accurate, are time-consuming for supporting real-time tasks in dynamic datacenter environments. Machine learning (ML)-based methods, particularly artificial neural network (ANN)-based surrogate models, have emerged as potential alternatives, but they struggle with generalization across diverse working conditions. Meanwhile, ML models’ performance in large datacenters still remains unclear. This research introduces a hybrid surrogate model combining ANNs and CNNs for the precise and rapid prediction of 3D temperature distributions in large datacenters. The proposed method incorporates an ANN for feature processing and a CNN for decoding spatial features, leveraging both to capture complex airflow patterns and temperature distributions under varying conditions. A dataset of 500 CFD-simulated temperature fields based on a real datacenter is established for model training and validation. The CFD method is evaluated by comparing the simulation results with experimental data. Results of the ML models’ performance indicate that the proposed hybrid surrogate model outperforms the conventional ANN model, reducing mean absolute error (MAE) by 87.44%. Additionally, the model is 300,000 times faster than CFD simulations, offering an efficient solution for further supporting real-time thermal management. Full article

Occupational exposure to airborne polymethacrylate (PMMA) particles during dental laboratory procedures poses an underexplored health risk. This study presents the first integrated Computational Fluid Dynamics (CFD) and real-time particle monitoring investigation of 0.5 µm PMMA particle dispersion during mechanical polishing in an actual clinic. We quantitatively assessed particle behavior in 30 s exposure scenarios by examining the effects of dental professional work orientations and comparing two mitigation strategies, rear-inlet portable air cleaners (PACs) and a Box Dust Collector (BC), with an emphasis on the safety of both personnel and patients. The findings establish that operatory airflow is a primary safety determinant: aligning the workflow with the main airflow (0°). Furthermore, the combined use of PACs and BC demonstrated synergistic superiority, achieving the optimal reduction in peak concentrations and airborne residence time. PACs alone reduced working zone concentrations by up to 80%, while BC provided a crucial 40–60 s delay in initial plume dispersion. We conclude that effective exposure control requires a proactive, two-stage engineering defense: source confinement augmented by continuous ambient filtration. This research provides a robust, evidence-based foundation for defining airflow-aware ergonomic and combined engineering standards in the evolving digital era of dentistry. Full article

The air-gap airflow significantly influences the performance of high-speed slotless permanent magnet synchronous motors (HSSPMSM), yet this critical factor is frequently overlooked during the design phase, resulting in performance deviations. This paper presents the design and multi-physical analysis of a 10 kW/40,000 rpm HSSPMSM, explicitly accounting for air-gap airflow effects. A comprehensive coupling model integrating electromagnetic, thermal, mechanical, and airflow fields is established to guide the motor design. Based on this analysis, the motor dimensions and parameters are determined, and a prototype is fabricated. Experimental validation demonstrates that the developed HSSPMSM successfully meets the design specifications. Considering air-gap airflow can obtain more accurate thermal design results with an accuracy improvement of 6.8% compared to not considering air-gap airflow. The close agreement between the simulated and measured performance confirms the effectiveness of the proposed design methodology that incorporates airflow effects. Full article

This study investigates the optimization of crushing and screening efficiency in hammer mill systems through aerodynamic analysis. The research focuses on cucumber vine stalks characterized by high moisture content, elevated cellulose concentration, and pronounced mechanical toughness. Using key operating parameters that significantly influence the gas flow field as the starting point, single-phase gas flow field numerical simulations and characteristic simulations were conducted using the computational fluid dynamics (CFD) software Fluent. A two-way coupling method combining Fluent and the discrete element method (DEM) software EDEM was employed to perform gas–solid coupled numerical simulations and operational characteristic simulations of the pulverizer’s grinding and screening process. This revealed the influence patterns of gas flow disturbances on the grinding and screening process and the mechanism for performance enhancement. Finally, field testing was conducted. Based on experimental results, the optimized operating parameters were determined as follows: rotor speed of 2569 r/min, fan opening of 62.55%, and feed rate of 7.64 kg/min. Under these optimized conditions, the crushing productivity of cucumber vine stalks reached 337 kg/h, with an energy consumption of 5.59 kW·h/t. The deviation between the actual and theoretical values for productivity was less than 6%, while the deviation for energy consumption per ton was less than 3%. These findings provide a theoretical foundation and experimental basis for further research into the mechanism of external airflow disturbance in the crushing and screening process, aiming to enhance crushing efficiency and reduce energy consumption. Full article

Low-quality fine-grained coal cannot be effectively separated in a conventional gas–solid fluidized bed. To enhance the density stratification and separation of low-quality fine-grained coal, this paper introduces a vibration force field to create a vibrating airflow composite force field. By investigating the force characteristics and sorting behavior of particles within this vibrating airflow composite force field, we reveal the mechanical properties of both high-density and low-density particles. An energy dissipation model for the vibrational energy among particles in the bed is established, clarifying how vibration acceleration varies between the front and rear sections of the bed. The experimental results indicate that acceleration at the feeding end is significantly greater than that at the discharging end. This higher acceleration at the feeding end facilitates the stratification and segregation of selected particles, while acceleration at the discharging end provides the necessary energy for the transport of gangue. The acceleration curve for low-density particles exhibits greater fluctuations compared to that for high-density particles; additionally, the forces acting on these particles along the y-axis direction promote density segregation. The forces tend to decrease gradually along the z-axis direction, which aids in particle migration and movement. The particle-sorting effectiveness within this vibrating airflow composite force field initially increases with rising vibration frequencies and gas velocities before subsequently decreasing. Under a frequency of 30 Hz and a gas velocity of 35 cm/s, the ash content and yield of the clean coal product from the bed are 7.1% and 52.6%, respectively, achieving the maximum degree of ash separation. Full article

Large-scale lithium-ion energy storage systems (ESSs) are indispensable for renewable energy integration and grid support, yet ensuring long-term reliability under field conditions remains challenging. This study investigates degradation trends in a 50 MW-class ESS deployed on Jeju Island, South Korea, focusing on two indicators: direct current internal resistance (DCIR) and state-of-health (SOH). Annual round-trip (capacity) and hybrid pulse power characterization (HPPC) tests conducted from 2023 to 2025 quantified capacity fade and resistance growth. A polynomial-regression-based temperature compensation was applied—compensating DCIR to 23 °C and SOH to 30 °C—which reduced environmental scatter and clarified year-to-year degradation trends. Beyond mean shifts, intra-bank variability increased over time, indicating rising internal imbalance. A focused case study (Bank 03-01) revealed concurrent SOH decline and DCIR escalation localized near specific racks; spatial maps linked this hotspot to heating, ventilation, and air conditioning (HVAC)-driven airflow asymmetry and episodic fan operation. These findings underscore the importance of combining temperature compensation, variability-based diagnostics, and spatial visualization in field ESS monitoring. The proposed methodology provides practical insights for the early detection of abnormal degradation and supports lifecycle management of utility-scale ESSs under real-world conditions. Full article

With the rapid development of solar thermal power generation technology, the structural stability of the dish solar concentrator system under complex wind environments has become a critical limiting factor for its large-scale application. This study investigates the flow field distribution and structural response under fluctuating wind loads using computational fluid dynamics (CFD). A three-dimensional model was developed and simulated in ANSYS Fluent under varying wind angles and speed cycles. The results indicate that changes in the concentrator’s orientation significantly influence the airflow field, with the most adverse effects observed at low elevation angles (0°) and an azimuth angle of 60°. Short-period wind loads (T = 25 s) exacerbate transient impact effects of lift forces and overturning moments, markedly increasing structural fatigue risks. Long-period winds (T = 50 s) amplify cumulative drag forces and tilting moments (e.g., peak drag of −73.9 kN at β = 0°). Key parameters for wind-resistant design are identified, including critical angles and period-dependent load characteristics. Full article

Although accurate quantification of forest soil CO₂ emissions is critical for improving global carbon cycle models, traditional chamber and gradient methods often underestimate fluxes under windy conditions. Based on long-term field observations in a subtropical maple forest, we quantified the interaction between canopy-level winds and soil pore air pressure fluctuations in regulating vertical CO₂ profiles. The results demonstrate that canopy winds, rather than subcanopy airflow, dominate deep soil CO₂ dynamics, with stronger explanatory power for concentration variability. The observed “wind-pumping effect” operates through soil pressure fluctuations rather than direct wind speed, thereby enhancing advective CO₂ transport. Soil pore air pressure accounted for 33%–48% of CO₂ variation, far exceeding the influence of near-surface winds. These findings highlight that, even in dense forests with negligible understory airflow, canopy turbulence significantly alters soil–atmosphere carbon exchange. We conclude that integrating soil pore air pressure into flux calculation models is essential for reducing underestimation bias and improving the accuracy of forest carbon cycle assessments. Full article

Wind and sand disaster prevention is a critical challenge for global environmental sustainability, with mechanical wind fences being key engineering measures. Current fences, including solid and permeable types, often struggle to balance environmental impact, windbreak efficiency, and stability. Solid fences provide effective sand control but have limited windbreak efficiency, while permeable fences improve airflow but require deep burial and are prone to erosion on uneven terrain. This study proposes a novel composite wind fence with a polylactic acid (PLA) sandbag base and a fiber mesh top, combining stability and permeability. We assessed windbreak performance using computational fluid dynamics simulations and verified results through wind tunnel experiments. Results show that the novel composite wind fence enhances windbreak efficiency and stability by optimizing airflow distribution, with the PLA sandbag base suppressing high–speed airflow and mesh fence weakening of leeward side vortices. Under wind speeds of 10 m/s, 18 m/s, and 28 m/s, the effective protection distance of the novel composite wind fence improved by 22.33% to 36.51%, 10.96% to 34.22%, and 0.94% to 28.98%, respectively, compared to single PLA and mesh wind fence. The optimal row spacing for the novel wind fences in three rows is 12 h when the incoming wind speed is 10 m/s, while the recommended spacings are 8 h and 6 h for wind speeds of 18 m/s and 28 m/s, respectively, ensuring continuous and effective protection. These findings present a novel wind fence technology with improved wind resistance, a more stable structure, and prolonged protective effects, offering an effective solution for environmental conservation initiatives aimed at preventing wind and sand disasters while promoting the sustainability of ecosystems. Full article

The uneven distribution of airflow on the blade surface of a yaw wind turbine triggers a complex non-constant flow, resulting in turbine flow field operation disorder, which, in turn, affects the structural field. In view of the different degrees of influence of different blade materials on the structural characteristics of a wind turbine, a numerical simulation of the flow field and structural field of the horizontal-axis wind turbine under different yaw conditions is carried out by using the fluid–solid coupling method to quantitatively analyse the degree of influence of the material on the structural characteristics of the wind turbine. The results show that the average velocity of the wake cross-section shows a trend of decreasing, then increasing, and then stabilising at all yaw angles. The larger the yaw angle, the wider is the vortex structure dispersion. As the wake develops downstream, the turbulence intensity is shown to decrease and then increase, and the yaw perturbation exacerbates the turbulence disorder in the wake flow field. Along the wind turbine blade spreading direction, the blade deformation phenomenon is significant. The yaw angle increases, the wind turbine blade deformation increases, and the maximum blade stress first increases and then decreases. At a 15° yaw angle, the airflow on the blade surface is more easily separated, and vortices are formed in the vicinity, which impede the airflow in the boundary layer and lead to a reduction in the velocity in the boundary layer in this region. The minimum deformation and maximum stress of the three materials under a 15° yaw angle indicate that the blades are more capable of resisting external deformation under this condition, so 15° yaw is the best operating condition for the wind turbine. This paper employs different materials to quantitatively analyse the extent to which structural characteristics influence wind turbine performance. The findings from this research can provide valuable insights for optimising wind turbine designs. Full article

Efficient pesticide application remains a critical resource-management challenge in modern agriculture, where limited spray penetration reduces treatment efficacy, wastes chemical inputs, and increases environmental losses. This study quantified the effect of air-assisted spraying (AAS) on droplet deposition in two contrasting field crops, oilseed rape and wheat. Field trials were conducted using a sprayer equipped with an adjustable airflow module, and spray coverage was measured with water-sensitive papers at multiple canopy heights and orientations. In oilseed rape, AAS improved deposition on front-facing and top surfaces in the lower canopy, for example, increasing top-surface coverage at 90 cm from 53.4% to 65.5% at 6 km∙h⁻¹, indicating more uniform distribution and enhanced penetration. In wheat, which typically exhibits a more open canopy structure compared to oilseed rape, AAS effects were smaller and less consistent, with the greatest gain on front-facing lower surfaces (from 13.3% to 21.9% at 7 km∙h⁻¹). Although drift was not measured in this experiment, previous studies using the same sprayer prototype demonstrated measurable reductions, supporting the environmental relevance of improved deposition. These results highlight the role of canopy architecture in determining AAS performance and underscore the technology’s potential to reduce pesticide inputs, minimize off-target losses, and improve the resource efficiency of crop protection in line with EU Farm to Fork objectives. Full article

As the operational speeds of subway trains in China incrementally increase to 160 km/h, the enclosed nature of tunnel environments poses significant challenges by restricting free airflow. This limitation leads to intense airflow disturbances and turbulence phenomena within tunnels, consequently exacerbating aerodynamic noise issues. This study utilizes compressible Large Eddy Simulation (LES) and acoustic finite element methods to construct a computational model of aerodynamic noise for subway trains within tunnels. It employs this model to compare and analyze the near-field noise characteristics of subway trains traveling at 120 km/h on open tracks versus in infinitely long tunnels. The findings indicate that the distribution of sound pressure levels on the surfaces of trains within tunnels is comparatively uniform, overall being 15 dB higher than those on open tracks. The presence of a high blockage ratio in tunnels intensifies the cavity flow between two air conditioning units, making it the region with the highest sound pressure level. The surface sound pressure spectrum within the tunnel shows greater similarity across different segments, with low-frequency sound pressure levels notably enhanced and high-frequency levels attenuating more rapidly compared to open tracks. It is recommended that in tunnels with high blockage ratios, the positioning of subway train air conditioning should not be too high, overly concentrated, submerged, or without the use of sound-absorbing materials. Such adjustments can effectively reduce the sound pressure levels in these areas, thereby enhancing the acoustic performance of the train within the tunnel. Full article

The subject of the research was a prototype two-row sprayer, equipped with a centrifugal fan and directed air-jet emission system, dedicated to the chemical protection of berry plantations, and, in particular, blackcurrants. The prototype was set up with two configurations: “offset”, in which the opposing air streams were “offset” by 0.5 m, and “face-to-face”, when they were positioned opposite each other. The field experiments were carried out on a blackcurrant plantation (Tisel cv.; bush spacing of 4.0 × 0.5 m; height 1.2 m; width 2.5 m). The spray deposition within the crop canopies as well as spray drift to the air and to the ground were assessed using the fluorescence method in order to compare the quality of treatments performed with the two-row sprayer and a conventional axial fan sprayer with radial air discharge system. Spray applications were performed at spray volume 300 L∙ha⁻¹ and working speed 6 km h⁻¹ by both sprayers. The plantation was sprayed with 0.25% water solution of a fluorescent tracer BF7G. The in-canopy spray deposit and spray drift were evaluated using artificial targets made of filter paper. Although directed air-jet sprayer in two configurations (“offset” and “face-to-face”) and conventional one produced similar deposits within the bushes, the spray loss from the directed air-jet sprayer was considerably lower (25.1–32.2%) than that from the conventional sprayer (76.9–81.8%) generating considerably greater airflow volume. Lower PPP losses mean lower environmental impact, which is in line with integrated plant protection. The research responds to numerous inquiries from sprayer manufacturers and blackcurrant growers regarding the most appropriate configuration of the air flow outlet planes. The results obtained will contribute to increasing the efficiency of spraying and facilitate the implementation of the European Green Deal and the achievement of the target of a 50% reduction in the use of plant protection products after 2030 in the EU. Full article

Sprayers for vineyards with solution recovery represent an important innovation, offering several advantages, the most important being the efficient use of pesticides and environmental protection. This paper presents the experimental equipment designed to study the treatment process of grapevine foliage, the applied research methods, and the results of optimizing key technological parameters (hydraulic pressure p of the working solution, speed V of the airflow at the nozzle outlet) and design parameters (surface area S of the central orifice of the diffuser) in different growth stages of grapevines with varying foliar density ρ, the response function being the recovery rate of the working solution. The construction of the SVE 1500 (Experimental model, manufactured at the Institute of Agricultural Technology “Mecagro”, Chisinau, Republic of Moldova) vineyard sprayer with solution recovery is presented, along with test results obtained in field conditions, which demonstrated that the experimental model of our machine ensures a 38% reduction in working solution consumption during the active vegetation phase while maintaining treatment quality in compliance with agrotechnical requirements. The SVE 1500 machine can be towed with a sufficient turning radius for use in modern vineyard plantations. Construction documentation has been developed for the production and delivery of the experimental batch of SVE 1500 machines to agricultural enterprises. Full article

The rotor airflow intensity and distribution characteristics of plant protection UAVs vary significantly with spatial positions below the rotor. Consequently, changes in the rotor–nozzle distance directly affect droplet motion and deposition patterns. To optimize the spraying effect of UAVs, this study combined a numerical simulation of rotor airflow and droplet deposition at different vertical distances between rotor and nozzle with field validation tests. The simulation results revealed that airflow intensity initially increases and then decreases with greater rotor–nozzle distance, peaking at 300–400 mm below the rotor with a maximum airflow velocity of 8.1 m/s. At 360 mm, the droplet swarm achieved its highest average velocity, corresponding to optimal deposition effect. Field tests confirmed a non-linear relationship between rotor–nozzle distance and droplet deposition. Droplet deposition first increased but declined sharply beyond the optimal range. When the distance was 360 mm, the target area exhibited the highest droplet deposition of 0.766 μL·cm⁻² and the lowest drift rate of 23.31%. Although a certain deviation existed between numerical simulation results and field test values, both methods consistently identified 360 mm as the ideal distance for balancing deposition efficiency and drift control. These findings provide actionable insights for field trial design and advance precision spraying strategies for plant protection UAVs. Full article