Search Results (90)

In-flight icing poses a major risk to the flight safety and operational availability in aviation and particularly to small electric aircraft. One suitable ice protection system (IPS) concept is the electrothermal IPS; however, it often suffers from high power consumption if not properly optimized. Ducted fans are a promising propulsion technology for urban air mobility applications, but effective IPSs for ducted fan propellers have been rare thus far. This work thus presents a framework for the development of an energy-efficient electrothermal IPS for application in an off-the-shelf ducted fan propeller. Three-dimensional ice accretion simulations of the ducted fan’s assembly were performed under centrifugal loads using the commercial icing simulation code ANSYS^® FENSAP-ICE-TURBO^™ and the most critical areas for ice accretion on the ducted fan were identified. On the basis of the ice accretion simulations, the expected performance change of the ducted fan due to ice accretion on the rotor blades was evaluated. The placement and activation of the heating elements on the rotor blades were investigated and optimized using a one-dimensional electrothermal de-icing solver. Full article

This study addresses pressure regulation in an induction-motor-driven centrifugal fan and introduces two complementary novelties: a Softsign-PI controller that shapes the tracking error via a Softsign nonlinearity before PI regulation and a hybrid starfish optimization with a differential evolution (hSFOA-DE) scheme for automatically tuning the controller parameters. The approach is evaluated on an experimentally validated nonlinear fan–motor model and benchmarked against modern metaheuristics—starfish optimization algorithm (SFOA), animated oat optimization (AOO), electric eel foraging optimization (EEFO), differential evolution (DE), particle swarm optimization (PSO)—as well as classical tunings—Murrill-based 2-DOF PID, Tyreus–Luyben PID and Ziegler–Nichols PI. Statistical summaries and boxplots indicate superior central tendency with reduced run-to-run variability; fitness–evolution curves show faster convergence; and time-domain performance metrics confirm improved transient and steady-state behaviour. Objective function comparisons further show the lowest values of both the Zwe-Lee Gaing (ZLG) and integral of absolute error (IAE), supporting advantages in robustness and tracking accuracy of the proposed approach. These gains reduce overshoot and cumulative error, which can lessen throttling losses and actuator duty in fan/pump service, suggesting potential energy and maintenance benefits. Full article

Personal thermal management systems, particularly neck fans, are increasingly popular for providing hands-free, localized cooling to enhance user comfort. We investigate the aerodynamic performance of compact forward-curved centrifugal impellers (<50 mm in diameter) with 30, 28, and 24 blades, selected through benchmarking of commercial products. A baseline impeller and casing were reverse engineered by using 3D scanning and CAD modeling methods, followed by blade count modifications under consistent geometric constraints. CFD simulations in ANSYS Workbench 19.1 were conducted to examine velocity fields, pressure distribution, and flow rate. Results indicate that blade number significantly influences airflow and efficiency: the 28-blade impeller achieved the highest outlet velocity, while the 30-blade configuration provided smoother pressure recovery but higher flow resistance. These insights aid the design of more efficient wearable cooling devices. Full article

Large-scale backward-curved centrifugal fans without volutes are extensively employed in enclosed air-cooled electric motors owing to their exceptional heat dissipation performance. This category of fans features substantial blade dimensions and a multitude of optimization parameters, which introduce challenges such as diminished predictive accuracy in high-dimensional optimization spaces. To address these issues, this paper proposes a blade optimization design methodology based on a GA-Kriging surrogate model. Sobol’s global sensitivity analysis is first employed to reduce model dimensionality. Subsequently, a high-fidelity aerodynamic performance prediction model is constructed through the integration of a Genetic Algorithm (GA) and a Kriging model. A constrained optimization is then conducted with volumetric flow rate and static pressure as the design objectives, and shaft power along with geometric point coordinates as the constraints. Experimental test results demonstrate that the fan optimized via the surrogate model, while maintaining low prediction error, achieves a 14% increase in volumetric flow rate and a 20% improvement in static pressure. This outcome indicates a significant enhancement in the overall aerodynamic performance. Full article

Domestically developed wheat breeding plot combine harvesters in China currently utilize cyclone separation self-cleaning systems. However, these systems struggle to meet the agronomic requirement of zero wheat grain residue. Seed mixing caused by residual grains can compromise the accuracy of entire breeding field trials. This study focused on the structural design of a cyclone separation self-cleaning system based on high self-cleaning agronomic requirements. Research was conducted on the key structural and operational parameters of the cyclone separator and the negative-pressure centrifugal fan, preliminarily determining the ranges for critical parameters such as the diameter of the cylindrical section of the separator wall, the dust outlet diameter, and the rotational speed of the negative-pressure centrifugal fan. A test bench for the cyclone separation self-cleaning system of wheat breeding plot combine harvesters was designed and developed. Through single-factor experiments and Box–Behnken design optimization, the effects of key parameters on system performance were investigated. The optimal parameter combination—cylindrical section diameter of 614 mm, dust outlet diameter of 290 mm, and fan speed of 1495 r/min—achieved a self-cleaning rate of 100%, self-cleaning time ≤ 12 s, loss rate of 1.70%, and impurity rate of 0.16%, fully meeting the requirements for high-quality, rapid, and effective separation and self-cleaning operations. Full article

As part of a joint research project between the Institute of Fluid Mechanics (LSTM) and the Institute of Fundamentals and Theory of Electrical Engineering (IGTE), an international benchmark case for fluid–structure–acoustic interaction was developed. The research focused on an enclosed centrifugal fan, and its aerodynamic, aeroacoustic and structure–acoustic properties were characterised through experimental measurements. This paper provides an overview of the centrifugal fan, its enclosure and the test rig used for the experimental investigations. Rather than interpreting the results, the focus is on presenting the benchmark case and providing an overview of the available data. The entire benchmark dataset is listed and freely accessible via the Zenodo European platform in the EAA benchmark data collection. Full article

This study employed a combined approach of computational fluid dynamics (CFD), numerical simulations, and wind tunnel tests to investigate droplet drift characteristics and develop prediction models in order to address the issues of low pesticide utilization rates and high drift risk, associated with droplet drift during agricultural unmanned aerial vehicle (UAV) spraying, as well as the unreliable results of field experiments. Firstly, a numerical model of the rotor wind field was established using the multiple reference frame (MRF) method, while the realizable k-ε turbulence model was employed to analyze the flow field. The model’s reliability was verified through wind field tests. Next, the Euler–Lagrange method was used to couple the wind field with droplet movement. The drift characteristics of two flat-fan nozzles (FP90-02 and F80-02) were then compared and analyzed. The results showed that the relative error between the simulated and wind tunnel test values was within 20%. Centrifugal nozzle experiments were carried out using single-factor and orthogonal designs to analyze the effects of flight height, rotor wind speed, flight speed, and droplet size on drift. The priority order of influence was found to be “rotor wind speed > flight height > flight speed”, while droplet size (D_V50 = 100–300 µm) was found to have no significant effect. Based on the simulation data, a multiple linear regression drift prediction model was constructed with a goodness of fit R² value of 0.9704. Under the verification condition, the relative error between the predicted and simulated values was approximately 10%. These results can provide a theoretical basis and practical guidance for assessing drift risk and optimizing operational parameters for agricultural UAVs. Full article

This study presents a computational–experimental assessment of two industrial centrifugal fans used in cement production, focusing on aerodynamic optimization and energy efficiency validation. The first case concerns a Farin Kiln Filter Fan initially constrained by existing inlet duct geometry, which caused vortex formation, flow asymmetry, and a pressure loss exceeding 15%. CFD analyses identified major inlet vortices and asymmetric splitter loading, guiding a redesigned configuration with an expanded fan body (1982–2520 mm), an increased outlet width (1808–1858 mm), and a vortex breaker to stabilize inlet flow. CFD simulations indicated a flow rate of 601,241 m³/h, static pressure of 2200 Pa, and total pressure of 2580 Pa, achieving an 83% efficiency. Field validation confirmed a 34.4% reduction in shaft power, 30% decrease in torque, and 4% gain in efficiency, corresponding to 449 MWh/year energy savings and 180 t CO₂/year emission reduction, assuming 8000 operational hours. The second case involves an Induced Draft (ID) Fan designed for 441,643 m³/h flow at 990 rpm. Transient CFD simulations using the SST k–ω model captured rotor–stator interaction and confirmed the effectiveness of the design revisions in suppressing swirl and flow separation. The optimized design achieved 8653 Pa static pressure, 9203 Pa total pressure, and 83% efficiency under design conditions. Field measurements showed a 26.2% drop in shaft power and 19.6% improvement in efficiency, yielding 2527 MWh/year energy savings and an estimated 1011 t CO₂/year emission reduction. Overall, the CFD-guided redesign framework demonstrated strong alignment between simulations and field measurements, highlighting the method’s practical relevance for improving fan performance and energy sustainability in industrial systems. Full article

A low-cost, dynamic flux chamber optimized for landfill emissions measurement was designed, fabricated, calibrated, and validated for measurements of methane flux ranging from 0 to 150 g/m²-day. A centrifugal blower fan and a flow meter were plumbed in series to draw a bypass flow through the flux chamber. Both ambient and chamber methane concentrations were measured using the arrays of four low-cost metal oxide sensors. Leveraging the sensors’ overlapping sensitivity to changes in methane concentration, temperature, and humidity, multiple linear regressions were trained on laboratory data and combined into a piecewise methane calibration function. An algorithm was developed to select the most useful interaction terms among all sensor responses to optimize the predictors in each model. The piecewise regions for methane measurement were 0–100 ppm, 100–1500 ppm, and 1500–12,000 ppm. The root mean squared errors for each piecewise region were 3.1 ppm, 21 ppm, and 307 ppm, respectively. Controlled quantities of methane were delivered to the flux chamber in a laboratory setting for validation. Measurements yielded good agreement with an RMSE and MBE of 7.3 g m⁻² d⁻¹ and 2.2 g m⁻² d⁻¹, respectively. The flux chamber was tested at a closed landfill to validate its ability to autonomously and continuously operate in the field. Full article

The paper describes an installation and procedure for evaluating the velocity profile for the airflow produced by the fan of the cleaning unit of a New Holland wheat combine harvester. The velocity profile is based on measurements taken at 52 points spread over the entire surface of the top and bottom sieves, for different speeds of the fan, different positions of the wind boards and different opening positions of the sieves. The experimental data obtained were graphically represented using the Radial Basis Function (RBF) interpolation model and highlighted that the airflow generated by the fan at the upper screen level, in the longitudinal plane and, especially, in the transverse plane, is distributed unevenly, and depends on the fan rotor speed, the opening of the louvers of the two screens and the arrangement of the two deflectors. The correct adjustment of the cleaning unit and correct evaluation of the air velocity profile over the sieves result in the reduction in grain losses from the upper sieve due to grain flotation, reduction in the content of broken grains in the grain tank due to the reduction in the material flow from the tailing auger as well as reduction in the impurities content of the grain tank due to better separation of the material over the surface of the lower sieve. 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

Orchard air-assisted sprayers have become key equipment for the prevention and control of fruit tree diseases and pests. However, centrifugal fans are rarely used in orchard air-assisted sprayers. To address the issue that the airflow generated by single-duct centrifugal air-assisted sprayers is insufficient to cover the lower canopy, a flow-guiding device for the lower canopy of fruit trees was designed. The Flow Simulation software of SOLIDWORKS 2021 was used to simulate the airflow field, and various structural parameters of the air outlet were analyzed to determine the optimal configuration of the upper edge inclination angle, the position of the upper air outlet, and the length of the upper air outlet. The results showed that the position of the upper air outlet had the most significant impact on the uniformity of the external flow field, followed by the upper edge inclination angle and the length of the upper air outlet. The optimal parameter settings for the air supply guiding device were determined as follows: upper edge inclination angle of 79°, upper air outlet position of 307 mm, and upper air outlet length of 190 mm. The verification test showed that the relative error between the simulated and actual airflow velocity measurements did not exceed 10%, confirming the accuracy of the simulation. The orchard field test showed that the average deposition density in the inner canopy of fruit trees was 78 particles/cm², indicating strong penetration ability; the distribution of spray droplets in the vertical direction of the canopy was uniform, meeting the requirements of fruit tree pesticide application operations. This technology provides a new approach for the application of centrifugal fans in fruit tree pesticide spraying. Full article

A self-propelled multi-duct air-delivered sprayer was developed to address the challenges of dense canopies and low pesticide utilization in closed-canopy apple orchards. It featured an intelligently adjustable spray bar and formed a directional air curtain via a centrifugal fan and a duckbill air outlet to improve droplet penetration. Using CFD simulations, the air duct size and the air outlet distance were optimized, and the field orthogonal test was carried out with driving speed, nozzle pressure, and nozzle type as factors. The results showed that the optimal parameters were an air duct size of 230 × 110 mm, an air outlet distance of 350 mm, and a fan speed of 2160 r/min. Compared to liquid pump independent operation, liquid pump–fan cooperative operation significantly increased droplet deposition density (p < 0.05) and reduced the degree of dispersion. All three factors significantly influenced deposition density (p < 0.05), and nozzle type had the greatest influence on deposition density, followed by nozzle pressure, and then driving speed. Optimal performance was obtained at a 0.3 m/s driving speed, a 3 MPa nozzle pressure, and a 6502 nozzle type. Under the optimal combination of operating parameters, field verification tests demonstrated that cooperative operation achieved higher average coverage (60.54% vs. 48.30%) and average deposition density (71.34 vs. 60.54 droplets/cm²), with a more uniform coefficient of variation in droplet coverage on leaves (a range of 13.37–19.07% vs. 9.70–22.67%). These results indicate that the sprayer exhibits strong penetration and provides good uniform coverage, effectively increasing droplet deposition across different canopy heights. Full article

The multi-wing centrifugal fan is an important part of air conditioning systems, particularly in the automotive domain. Due to the compact structure and short blade passage of the fan, it may reduce the aerodynamic performance and generate noise. As a key part of the multi-wing centrifugal fan, the volute tongue has an important impact on the aerodynamic performance and noise of the multi-wing centrifugal fan. In this paper, the volute tongue of a multi-wing centrifugal fan is modified for air conditioning systems, and a novel gradient-radius volute tongue is designed. Specifically, a simulation calculation model for the multi-wing centrifugal fan is developed based on the Realizable k-ε turbulence model and the Ffowcs Williams–Hawkings (FW-H) equation. The simulation results are analyzed, and the reliability of the proposed method is assessed by comparing the total pressure efficiency and noise levels with the corresponding experimental measurements. Subsequently, the aerodynamic performance and noise characteristics of the gradient-radius volute tongue are investigated, with particular attention given to variations in the flow field, pressure pulsation, and noise before and after the modification. The results indicate that the gradient-radius volute tongue effectively attenuates the pressure pulsations arising from the interaction between the volute and the airflow, thereby reducing the tongue-region noise. Compared with the original fan, a noise reduction of 3.5 dB is achieved through the implementation of the gradient-radius volute tongue. Full article

Recent advancements in rice breeding have significantly increased production in China. However, high-yielding varieties require strong airflow for effective cleaning. Longitudinal-flow rice combine harvesters equipped with a centrifugal fan with four blades are widely used in China; however, these fans exhibit fluctuating cleaning performance and airflow maldistribution. To address these limitations, this study developed an innovative multi-blade cleaning fan design by incorporating the blade clocking effect, a concept not previously applied in centrifugal fans. To support the design process, the required airflow rates and reduction in static pressure were first analyzed. Based on these findings and fundamental fan design theory, three fan models were designed with blade clocking angles of 0°, 5.5°, and 10.5°, respectively. Three fan models were evaluated through computational fluid dynamics (CFD) simulations using a design of experiments approach based on Box–Behnken design response surface methodology to identify the optimal fan. The fan features a 10.5° clocking angle, meeting the airflow requirements for effective cleaning. In the test bench measurements, the setup with guide plate angles No. 1 and No. 2 at 32° and a fan speed of 1200 rpm was identified as optimal. The newly designed multi-blade cleaning fan overcomes the limitations of conventional four-blade designs, significantly enhancing airflow uniformity. Full article