Search Results (154)

Tip leakage degrades ducted fan performance and contributes to unsteady loading noise. This study investigates a wall-penetrating blade ring (WPBR) ducted fan for unmanned electric vertical takeoff and landing (eVTOL), replacing radial clearance with axial end face gaps. Six configurations of a 381 mm four-bladed rotor were evaluated at 5000 r/min under quasi-hover conditions: a conventional ducted fan, an internal blade ring rotor, and four WPBR cases with single-sided clearances of 0.8–2.0 mm. Sliding-mesh unsteady Reynolds-averaged Navier–Stokes simulations using the shear stress transport k-ω model were coupled with the Ffowcs Williams–Hawkings formulation. The WPBR formed a U-shaped cavity recirculation and redistributed the concentrated tip-region vortical structures. The 1.2 mm case retained 28.72 N of thrust, 2.1% above baseline, while reducing torque by 6.1% relative to the 0.8 mm case; its figure of merit remained lower. Its simulations predicted a reduction of 16.4 dB in the first blade-passing frequency level in the rotor plane and a predicted reduction of up to 15 dB in overall sound pressure level at 1 m. Thus, it represents a compromise among thrust, torque, and predicted acoustic performance rather than an aerodynamic optimum. A magnetically supported prototype operated up to 2000 r/min, demonstrating low-speed operability of the architecture for unmanned eVTOL propulsion. Full article

Geometric deviations can considerably degrade the aerodynamic performance of low-pressure turbine blades, especially as blade loading is increased for reduced blade count and weight. Stronger suction-side adverse pressure gradients then make the boundary layer more sensitive to leading-edge disturbances. In this work, 1781 measured leading-edge deviation samples are mapped onto the T106D-EIZ low-pressure turbine blade. The resulting profiles are compared with a Gaussian-process-based smooth deviation set. At the Zweifel coefficient Zw = 1.28, the measured deviations increase the mean loss by 5.1% relative to the nominal value, with a relative standard deviation of 14.2% and a 2.9% probability of a loss increase exceeding 30%. This impact is amplified at Zw = 1.30, where open suction-side separation occurs in 9.4% of the measured profiles. Leading-edge thickness variation is a major contributor to the loss variation. Leading-edge thinning strengthens the suction-side pressure spike, promotes local separation and transition, increases downstream friction loss, and weakens the boundary-layer momentum before the trailing edge. However, thickness reduction does not fully account for the high-loss risk observed in the measured profiles. For a pair with comparable leading-edge thickness, the loss coefficient is 0.1556 for the measured sample and 0.0469 for the corresponding smooth Gaussian process sample at Zw = 1.30. The additional risk is associated with measured local non-smoothness and irregular curvature variation, which disturb the leading-edge pressure-gradient development, increase suction-side cumulative loss and wake-mixing loss, and can trigger earlier large-scale separation. These results indicate that realistic leading-edge shape quality should be considered in tolerance assessment and robust aerodynamic design of highly loaded low-pressure turbine blades. Full article

Static wake steering can increase wind-farm power production, but its application to floating offshore wind farms requires assessment of the coupled wake, platform, structural, and station-keeping response. This study evaluates whether power-maximizing static yaw setpoints identified using the steady, control-oriented FLORIS model retain their benefit when transferred without re-optimization to a coupled FAST.Farm floating wind-farm model. The reference farm comprises four IEA Wind 15 MW turbines mounted on VolturnUS-S semi-submersible platforms. Greedy and static wake-steering operations are compared at three below-rated wind speeds, three sea states, and five matched turbulent-inflow realizations, resulting in 90 farm-level FAST.Farm simulations. Wake behavior is characterized through wake-center deflection, meandering, and velocity-deficit profiles, while turbine and mooring fatigue responses are evaluated using paired damage-equivalent-load statistics. Static wake steering increases mean farm power under all nine investigated wind–wave conditions. The gains are approximately 5.1–$5.2\%$ at $7\mathrm{m}{\mathrm{s}}^{-1}$, $5.0$–$5.1\%$ at $8\mathrm{m}{\mathrm{s}}^{-1}$, and $4.0$–$4.2\%$ at $9\mathrm{m}{\mathrm{s}}^{-1}$, with all paired $95\%$ confidence intervals remaining above zero. The gain results from a power redistribution in which the intentionally yawed upstream turbine incurs a local loss that is exceeded by the combined recovery of the downstream turbines. The fatigue response is strongly component- and turbine-dependent. The paired farm-mean blade-root DEL decreases by $0.82$–$2.24\%$, whereas the tower-base DEL increases by $0.76$–$2.78\%$, and the FairTen1 response generally increases by $0.88$–$2.92\%$. The farm-mean yaw-bearing response is mixed, ranging from a $1.15\%$ reduction to a $4.32\%$ increase. Turbine-level analysis reveals larger localized penalties, reaching approximately $10.4\%$ for the yaw-bearing DEL and $12.8\%$ for FairTen1. Spectral analysis associates the yaw-bearing response with yaw-induced aerodynamic and structural excitation, while the tower-base response is strongly influenced by low-frequency wave–platform dynamics. A complementary FLORIS sensitivity analysis demonstrates that the optimized aerodynamic benefit depends strongly on wind direction, spacing, wind speed, and turbulence intensity. For a Tampen-derived 11-turbine layout, resource weighting over the modeled 4–$13\mathrm{m}{\mathrm{s}}^{-1}$ interval produces an annual energy-contribution increase of $3.653\mathrm{GWh}{\mathrm{year}}^{-1}$, or $0.921\%$. These results provide numerical evidence that static wake steering can retain a positive power benefit in a coupled floating wind-farm environment, but controller assessment must include turbine- and component-specific dynamic loads rather than farm power alone. Full article

The increasing global demand for clean energy has established wind power as a leading solution for sustainable electricity generation. The efficiency and reliability of wind turbines are strongly influenced by blade design, which governs both aerodynamic performance and structural integrity. In this study, a wind turbine blade based on the National Advisory Committee for Aeronautics (NACA) 4412 airfoil was developed for composite manufacturing, with variations in laminate layers (4, 8, 12, and 16) to optimize stiffness, strength, and weight. To reduce prototyping costs and development time, the structural response under operational loads was simulated using ANSYS Workbench 2025 R1. The Taguchi method was employed to minimize the number of experimental trials, considering three factors at four levels each. A multi-objective optimization was then performed to minimize tip deformation and maximum stress while ensuring a safe failure index. The results indicated that force distance was the most influential factor, followed by laminate configuration, while force magnitude had a comparatively smaller effect within the tested range. The configuration with a force of 15 N, a force distance of 60 cm, and 12 laminate layers achieved a composite desirability of 0.9413, leading to a significant reduction in deformation and stress while maintaining structural safety. These findings validate the effectiveness of the proposed design and optimization framework and provide practical guidelines for the development of high-performance composite wind turbine blades. Full article

The high-value utilization market for crop straw renders the development of stubble management technology crucial. This study aims to reduce the energy consumption of L-shaped rotary blades during stubble-breaking. Based on a theory analysis of the rotary-cutting operation process, this study involved the burial of the in situ maize root–soil composite in an indoor soil bin, and investigated the effects of rotary speed (275, 330, 385, 440 rpm) and working depth (50, 85, 120 mm) on torque, power, and energy. Field verification yields an overall average relative error of 2.76% across six replicates, verifying that the indoor test method can reliably reproduce field cutting conditions. As the high-speed video images show, a reduction in rotary speed coupled with an augmentation in working depth has the potential to result in residue entanglement and secondary cutting, thereby leading to an escalation in consumption. As the working depth increased, peak torque appeared at a deeper penetration position. The analysis of the computer-aided geometric model section of the root–soil composite indicated that the diameter of the branching root was the primary factor influencing peak torque. At a working depth of 85 mm, the average power savings ranged from 2.26% to 24.8% compared to 50 mm and 120 mm. Despite the increase in average power, peak power, and specific energy requirements at all operational depths with increasing rotary speed, torque reached its minimum at 385 rpm. At 385 rpm, average torque hits its minimum to mitigate component wear, though power and specific energy rise monotonically with rotational speed. The multi-index evaluation balancing mechanical load, energy loss, and residue delivery identifies 385 rpm paired with 85 mm depth as the optimal parameter set. The optimized parameter combination delivers a quantifiable sustainable residue management scheme that balances ecological residue treatment and economic machinery operation costs, supporting low-carbon, sustainable production. Full article

To investigate the dynamic transmission of unsteady hydraulic excitation within pumped-storage units, this study presents a numerical investigation on the three-dimensional shafting vibrations of a pump-turbine based on a one-way transient fluid-structure interaction approach. To resolve the flow field, we adopt the shear stress transport (SST) k-ω turbulence model in conjunction with the Zwart-Gerber-Belamri (ZGB) cavitation model, and the combined numerical approach is first calibrated against experimental measurements. The results indicate that under the 70% partial load, an eccentric helical vortex rope develops inside the draft tube, generating intense low-frequency pressure pulsations that induce chaotic shaft orbits and distinct orbital drift at the turbine guide bearing. Conversely, near the optimal efficiency point (90% load), the vortex rope transitions into a slender, straight conical core, yielding minimum vibration magnitude and exceptional operational stability. At the 100% rated load, the vortex rope expands into a robust straight conical structure extending continuously into the elbow section. Stress analysis reveals that while equivalent stress concentrations consistently occur at the blade root regions, a reduction in the cavitation number at both 90% and 100% loads leads to a counterintuitive decline in blade surface peak stress values. Additionally, stiffness sensitivity analysis demonstrates that the relative change rates of the shaft runout are highly sensitive to the stiffness variations of the turbine guide bearing, where a stiffness reduction triggers a substantial runout growth of approximately 100% along the X- and Y-directions, whereas the variations in the upper and lower guide bearings exert extremely weak impacts. Full article

Non-periodic leading-edge wear near the impeller tip is investigated with respect to the aerodynamic performance, steady flow organization, and near-stall unsteady evolution of a centrifugal compressor. A full-annulus three-dimensional impeller–vaned-diffuser model is established for a baseline configuration (O-M) and a non-periodically worn configuration (W-M). The two configurations are compared in terms of performance characteristics, near-tip pressure coefficient, static pressure, entropy, relative Mach number, three-dimensional vortical structures, and pressure fluctuation signals. The W-M generally produces a lower total pressure ratio than the O-M, with a maximum reduction of approximately 0.7%. Nevertheless, the isentropic efficiency is slightly improved over the main operating range, with a peak increase of about 0.6%, and the near-stall flow rate shifts toward a lower value. Pressure coefficient distributions at 95% span show that leading-edge wear weakens both the pressure-side pressure peak and the suction-side suction peak of the worn blades, redistributing the near-tip loading from a highly leading-edge-concentrated form to a broader chordwise distribution. The steady flow fields indicate that wear does not eliminate local low-pressure or high-entropy regions; rather, it reorganizes their circumferential arrangement, converting originally synchronized low-pressure zones, high-entropy bands, and high-speed shear layers into a non-uniform pattern with alternating strong and weak passages. Near-stall unsteady results further reveal that pressure cells, high-entropy zones, and large-scale vortical structures in the O-M exhibit clear cross-passage propagation, whereas the corresponding disturbances in the W-M remain predominantly localized, dispersed, and asynchronous. These results demonstrate that, for the wear location and blade-to-blade distribution considered here, non-periodic leading-edge wear affects stability primarily by weakening the circumferentially coherent amplification of disturbances, rather than by simply reducing all local loss sources. Full article

This study presents the design, development, and experimental validation of an automated flat blade grinding machine for the wood processing and plastic recycling industries in Ecuador. The machine was engineered following the VDI 2221/2222/2225 design methodology, integrating SolidWorks-based 3D modeling and ANSYS finite element analysis (FEA) to validate critical structural components. The selected configuration includes a Type 6 alumina grinding wheel (38A-60-K-VS), a mechanical clamping system, cutting fluid cooling, and a hardwired electromechanical control system that does not require a programmable logic controller (PLC). FEA results confirmed adequate safety factors (ηs > 16; ηf > 14) for the ACME 3/4–8 power screw under operational loads. Experimental testing on blade specimens (thickness: 3 mm; length: 70 mm; steel up to 60 HRC) demonstrated that four grinding passes at a 45° inclination angle reduced mean surface roughness (Ra) from 5.39 ± 1.83 µm (used blades) to 0.162 ± 0.092 µm, achieving values comparable to new blades (Ra = 0.601 ± 0.153 µm): a point-estimate reduction of 97% in mean Ra relative to the used-blade condition. The automated process reduced average grinding time by approximately 30% compared to manual methods, while maintaining noise levels within the 85 dB occupational exposure limit. Operator satisfaction surveys rated the system above 4.5/5.0 across all ergonomic and usability criteria. These results validate the proposed machine as a cost-effective, locally manufacturable solution to standardize blade maintenance in small and medium enterprises (SMEs) across Latin America. Full article

To overcome the computational bottlenecks of iterative Computational Fluid Dynamics (CFD) in turbomachinery design, this study introduces a real-time, data-driven inverse design framework for 2D uncooled, high-Reynolds turbine blades. The novelty of this work lies in the application of Kolmogorov–Arnold Networks (KAN), a distinct deep-learning architecture, to predict blade geometry and performance metrics from aerodynamic loading inputs. The foundation of the model is a comprehensive database of approximately 30,000 blade profiles, generated through an automated optimization pipeline coupled with the MISES solver. This dataset explores an extensive design space, covering inlet flow angles from $-{50}^{\circ }$ to $0^{\circ }$ and outlet angles from ${50}^{\circ }$ to ${75}^{\circ }$, with flow turning up to ${125}^{\circ }$. A rigorous benchmarking campaign compares KAN against Multi-Layer Perceptrons (MLPs) and Gaussian Process Regression (GPR), highlighting KAN’s capability to overcome the scalability bottlenecks of Gaussian Process Regression to enable real-time performance while achieving MLP-level accuracy with significantly fewer parameters. A further analysis regarding the trade-off between database size and filtration of unfeasible designs indicates that an optimal data filtration threshold exists, balancing noise reduction with model robustness. The final KAN tool achieves real-time inference speeds (∼0.1 s), reducing the design cycle by four orders of magnitude compared to traditional solvers, while maintaining high accuracy (mean outlet angle error of ${0.086}^{\circ }$ and Mach profile RMS error of $0.004$). Furthermore, the model’s predicted RMS error is exploited as a quantitative proxy for aerodynamic feasibility, identifying ill-posed inverse problems where the target loading cannot be physically realized. This metric enables the generation of comprehensive maps that rigorously delineate the boundaries of the viable design space across arbitrary aerodynamic loading styles, providing physics-aware guidelines for preliminary design. Full article

A 660 MW coal-fired unit was investigated to clarify the combustion behavior over a wide load range and the effects of static mixers on selective catalytic reduction (SCR) performance. A full-process CFD model covering the furnace, rear pass duct, and SCR system was established, and the combustion characteristics, NO_x formation, and SCR performance were analyzed over a boiler load range of 25–100%. The results showed that, as the boiler load decreased, the furnace heat release weakened, the high-temperature zone contracted, and the flame center shifted downward, with more pronounced flame maldistribution at 25% load. The average NO_x concentration at the SCR inlet first decreased and then increased with decreasing boiler load, reaching a minimum at 75% load. Without a static mixer, the NO_x concentration at the SCR inlet increased from 238 mg/Nm³ at 100% load to 312 mg/Nm³ at 25% load. After a static mixer was installed, the distance required for NH₃ homogenization downstream of the ammonia injection grid was markedly shortened, and the uniformity of the velocity, NH₃ concentration, and temperature fields at the SCR catalyst inlet was improved. In particular, the coefficient of variation in NH₃ concentration decreased from about 4–5% to about 2–3%, while the denitrification efficiency increased by about 1–5 percentage points compared with the case without a static mixer. The variation in denitrification efficiency among different boiler loads was also significantly reduced, indicating improved adaptability of the SCR system to wide-load operation. Among the tested configurations, the static mixer with small blades and a larger blade angle relative to the vertical plane showed the best overall performance. These results provide useful guidance for SCR system improvement in coal-fired units operating over a wide load range. Full article

Loading fluctuations and fatigue-related structural demand under turbulent wind conditions are important factors that limit the reliability of small wind turbines. This study investigates the separate effects of turbulence intensity and pitch angle on a 5 kW distributed variable-pitch wind turbine prototype using an OpenFAST-based aeroelastic model validated against field measurements. Under the adopted simulation setup and selected operating conditions, increasing turbulence intensity from 5% to 20% leads to a pronounced increase in the extreme blade-root flapwise bending moment and a substantial reduction in the estimated comparative fatigue life. The analysis also reveals a clear trade-off between aerodynamic efficiency and structural durability: among the tested pitch settings, the 6° case yields the highest power output, but also exhibits the largest load fluctuations and the shortest estimated comparative fatigue life. Adjusting the pitch angle to 0° or 12°, while reducing power to some extent, alleviates fatigue-related structural demand and increases the estimated comparative fatigue life. Overall, the results provide a validated prototype-level comparative assessment of how turbulence intensity and pitch angle influence aerodynamic performance, structural response, and fatigue-related demand in the studied turbine. Because the present work focuses on one prototype and does not include cross-turbine comparison or a full stochastic convergence study, the reported quantitative results should not be interpreted as directly generalizable to other turbine configurations. These findings may nevertheless provide a useful basis for future studies on load-aware pitch regulation under turbulent inflow. Full article

Turbulent wind conditions pose significant challenges to the blade structural reliability of small wind turbines. Different from the authors’ previous work, which mainly focused on the output characteristics of the same 5 kW prototype under variable inflow conditions, this study combines field-test observations with numerical simulations to further investigate the blade structural dynamic responses of a 5 kW variable-pitch wind turbine under both uniform inflow and extreme wind conditions. Owing to the unique pitch-regulation mechanism of the proposed turbine, two pitch-control modes, namely conventional power-limited pitch control and active stall pitch control, are comparatively analyzed to clarify their effects on blade load, stress, and displacement responses. The results indicate that, under uniform inflow conditions, stresses are concentrated near the leading edge of the blade mid-span, while the maximum displacement occurs at the blade tip. Both stress and displacement decrease with increasing conventional pitch angle. Under extreme wind conditions, increasing gust intensity causes a nonlinear growth in blade loads and aggravates blade structural response. During active stall pitch control, the load distribution pattern is generally consistent with that under conventional pitch control, whereas the blade structural response first decreases and then increases as the pitch angle is adjusted toward negative values. Under uniform inflow at the rated wind speed of 11 m/s, the blade-tip maximum displacement decreased from 56.51 mm under the +6° power-limited/reference pitch condition to 48.42 mm under the −6° active-stall-related pitch condition, corresponding to a reduction of approximately 14.3%. These results provide a useful reference for the blade structural design and control optimization of distributed small wind turbines under complex inflow conditions. Full article

To investigate the impact of continuous leading-edge curvature on the aerodynamic performance of transonic compressor blade profiles, schlieren observations and surface pulsating pressure measurements were conducted on the baseline profile CM1.2 and its optimized variant CM1.2-Y. The results indicate that the optimized profile can effectively reduce unsteady pressure pulsations at Mach numbers of 0.8 and 1.05, with a maximum reduction of 14.6 dB. At Mach number 0.95, the optimized design eliminates high-pressure pulsation regions on the pressure surface but intensifies local loading on the suction surface. The optimization of leading-edge curvature effectively reduces the extreme pulsations on the suction surface caused by shock wave interference under most operating conditions, and significantly improves the wave structure on the pressure surface, thereby comprehensively reducing the pressure pulsation level of the blade profile. Full article

The increasing deployment of wind energy has brought renewed attention to aeroacoustic noise generated by wind turbine blades, where broadband noise is primarily associated with vortex shedding at the trailing edge (TE) and leading edge (LE) of airfoils. Owls, particularly Tyto alba, exhibit wing morphologies such as serrations, velvet-like surfaces, and fringes that enable silent flight through aerodynamic noise suppression. This study presents a scoping review of the scientific literature on owl-inspired serration strategies applied to aerodynamic airfoils and wind turbine blades. The literature search was conducted across major academic databases, including Scopus, ScienceDirect, SpringerLink, and MDPI, covering publications from 1970 to 2025. A total of 69 experimental and numerical studies focusing on LE and TE serrations was analyzed. The review integrates aeroacoustic analysis with bio-inspired design perspectives. The analyzed studies consistently show that serrated geometries modify vortex dynamics and turbulence structures, leading to measurable acoustic benefits. Experimentally, the largest reductions reported for aerodynamic airfoils reached about 7 dB for both LE and TE serrations, mainly as broadband noise attenuation, in specific frequency ranges. Numerically, the highest reported reduction reached up to 21 dB for a serrated TE configuration, corresponding to spectral SPL reduction mainly below 1.6 kHz. The reviewed studies also indicate that the associated aerodynamic response is strongly configuration-dependent, ranging from limited penalties to measurable changes in lift, drag, power output, or structural loading. Numerical simulations further support experimental findings and highlight the importance of geometric parameters such as serration amplitude, wavelength, and spacing. Overall, bio-inspired serrations represent a promising passive strategy for aeroacoustic noise mitigation in wind turbines, drones, and rotating aerodynamic systems. Future research should focus on the multi-objective optimization of serration geometry, large-scale experimental validation, and the integration of bio-inspired concepts into industrial blade designs. Full article

Pre-sowing tillage under irrigated agriculture is associated with high energy demand and increased risk of soil structural degradation, particularly in heterogeneous loam soils of arid and semi-arid regions. This study presents the engineering optimization and field validation of a combined implement for single-pass rotary strip tillage and precision seeding developed for irrigated sierozem soils of Southern Kazakhstan. The research integrates analytical modeling of soil–blade interaction, optimization of rotary blade geometry, and comparative field experiments using an experimental prototype (FS-2.1). Analytical optimization identified an optimal blade installation angle of 54–56°, resulting in an approximately 22% reduction in specific cutting area. Field results demonstrated that the single-pass system formed a high-quality seedbed, with 85.2% of soil aggregates smaller than 25 mm and a surface leveling deviation below 5 mm. Compared with a conventional multi-pass technology, traction load, fuel consumption, and total energy input were reduced by 38%, 43%, and 54.5%, respectively. The results confirm that combining optimized rotary blade geometry with strip-based soil disturbance enables substantial energy savings without compromising agronomic performance. The proposed engineering solution provides a reproducible framework for low-traction, resource-efficient tillage–seeding systems suitable for irrigated agriculture in Southern Kazakhstan and comparable agroecological regions. Full article