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Dust concentration in coal mine roadways significantly affects worker safety and health. Effective dust control is critical for optimizing the mine ventilation system and creating a safer working environment. This study investigates the impact of ventilation duct arrangements on dust concentration in a heading face, aiming to identify the optimal configurations for minimizing dust levels and enhancing worker safety. Using numerical simulations based on the gas-solid two-phase flow model in Fluent, we analyzed the effects of varying duct outlet distances and heights on airflow patterns and dust dispersion. Mesh generation, grid independence verification, and detailed parameter settings ensured accuracy and reliability of the simulation results. Results indicate that positioning the duct outlet 8 m from the heading face reduces dust concentration to approximately 39 mg/m³, while setting the duct height at 1.5 m notably decreases dust levels in the worker breathing zone. A mesh density of 576,449 cells ensured convergence and computational efficiency with an error margin within 2%. The findings provide practical insights into ventilation system optimization for coal mine heading faces, contributing to improved occupational health and operational safety. Future research should focus on validating these results through field experiments and addressing complex real-world conditions. [ABSTRACT FROM AUTHOR]

In modern society, a significant proportion of time is spent indoors, where exposure to volatile organic compounds (VOCs) emitted by various office equipment and materials is common. These harmful gases can cause irreversible health damage upon inhalation. Therefore, reducing the concentration of indoor VOCs has become a topic of great concern. Selecting an appropriate ventilation strategy is an effective and practical method to lower pollutant concentrations. In this study, a typical office and its ventilation system were numerically simulated using the standard k-ε turbulence model and the component transport model in FLUENT. Four scenarios with different inlet airflow velocities and three scenarios with varying inlet airflow angles were evaluated. The concentrations and distributions of VOCs were analyzed at both seated and standing breathing planes as well as within the overall space. It was observed that higher inlet airflow velocities, within the limits of human comfort, accelerated indoor air exchange, reaching dynamic equilibrium more swiftly. Additionally, both the breathing zone and the indoor space exhibit lower average concentrations of VOCs after equilibrium was achieved as the inlet velocity increased. Furthermore, under a constant inlet velocity, an upward 45° airflow angle was found to create more effective indoor air mixing, reduce stagnant zones, and facilitate VOC removal, thereby lowering indoor VOC concentrations. Based on the findings, a ventilation strategy employing a larger inlet airflow velocity combined with an upward airflow angle is recommended to efficiently reduce indoor VOC concentrations, improve air quality, and mitigate health risks. These results provide valuable guidance for the design and implementation of ventilation systems in real-world engineering applications. [ABSTRACT FROM AUTHOR]

Aiming at the problem of difficulties in seed filling and seed cleaning caused by the small specific gravity, small size, and irregularity of quinoa seeds, a positive-negative pressure precision seed-metering device for quinoa seeds with a disturbed seed-filling mechanism was designed. The disturbed seed-filling mechanism can improve the seed-filling performance of the precision seed-metering device and reduce the power consumption required by the forced-draught fan. Positive pressure seed cleaning can solve the problem of pore blockage caused by small and light quinoa seeds and improve work stability. Taking Jili No. 3 seed as the research object, simulation analysis of the flow field in the air chamber of the precision seed-metering device was carried out by the Fluent 2021 R1 software. The influence of seed-sucking hole structure parameters (shape and number of seed-sucking holes, inclination angle of seed-sucking holes, and diameter of seed-sucking holes) on the flow field was analyzed by a pressure nephogram and a velocity vectogram. The optimal parameter combination was obtained as follows: a circular-cone-type shape of the seed-sucking hole, a number of 20 seed-sucking holes, a 70° inclination angle of the seed-sucking hole, and a 1 mm diameter of the seed-sucking hole. EDEM 2020 software and orthogonal test were used to optimize the design of the disturbed seed-filling mechanism. The influence of structural parameters of the disturbed seed-filling mechanism (groove radius of the disturbed seed-filling mechanism (GRDSM), arc of the disturbed seedfilling mechanism (ADSM), and position angle of the disturbed seed-filling mechanism (PADSM)) on the qualified index (Iq) of scooping seeds was analyzed. The optimal parameter combination was obtained: 1.3 mm GRDSM, 140° ADSM, and 25° PADSM. With the help of the JPS-12 test-bench, a response surface test was carried out with the qualified index (Iq), the miss index (Imiss), and the multiple index (Imul) as test indices, and the seed-sucking negative pressure, the seed-metering device rotation speed, and the seed-falling height as test factors. The optimal working parameter combination was obtained: -3.0 kPa seed-sucking negative pressure, 15 r/min seed-metering device rotation speed, 100 mm seed-falling height. Validation tests were carried out on the optimized seed-metering device, and the results showed that the Iq was 82.5%, the Imiss was 6.5%, and the Imul was 11%, which met the index requirements in JB/T 10293-2013 Technical conditions of single seed (precision) seeder. The results of this study can provide a reference for the design of machinery for the precision seeding of small seeds such as quinoa. [ABSTRACT FROM AUTHOR]

This study focuses on how fonts selected from different families have been used to test for disfluency. The motivation and standard for choosing a particular font for an experiment are not yet clearly defined from past studies. Drawing on methods in a systematic review of 10 articles published between 2007 and 2020, this article shows that authors prefer to use sans serif fonts in fluent conditions and serifs, scripts or handwritten fonts in disfluent conditions. In this study, disfluency manipulations were limited to reducing font sizes and percentages of grey or black. The largest size used was 56pt (fluent) and 18pt (disfluent) while the smallest was 12pt (fluent) and 10pt (disfluent). We observed that the opacity values of disfluent fonts ranged between 10% and 60%, making it unclear how disfluent a font can be. Apart from font sizes, fixation time, familiarity with materials and other controls influenced the results. This article reveals that a major gap still exists in research because of a lack of standard methods for determining the fonts used for testing subjects. [ABSTRACT FROM AUTHOR]

To address issues arising from chaotic water flow due to unreasonable pumping station operation and insufficient forebay design, this study took the Yanhuangding pumping station as a typical case. Numerical simulations using FLUENT software were conducted to examine different forebay patterns based on the Realizable turbulence model and the Eulerian multiphase flow model. The influences of different diffusion angles and different number of operating pumping stations on the flow field structure in the forebay were expounded. The results show that: ① As the diffusion angle increases, the number of vortices in the forebay flow rises from one to two. At diffusion angles of 25°and 30°, the vortex area occupies less of the forebay inflow, resulting in a more stable flow field. ② Reducing the number of operating pumping stations from five to two decreases the vortex area in the forebay from 31.42 m2 to 10.15 m2, with optimal forebay flow achieved when operating pumping stations 3# and 4#. The research results can provide reference and guidance for the design and renovation of similar pumping stations.

CANDU spent fuels in the Wolsung site have been stored in dry storage systems, such as concrete canisters and modular air-cooled storage system. The primary role of the canister is to ensure the integrity of the fuel during the storage period, which is significantly influenced by temperature. Thus, thermal analysis for the canister's components, especially for fuel cladding, is essential to demonstrate its safety. The thermal analysis has been conducted mainly for predicting the peak cladding temperature (PCT) since high temperature of the fuel can promote oxidation and cracking. As the expiration of storage license approaches, fuel transfer to final disposal should be prepared. This also requires a thermal analysis to predict minimum cladding temperature (MCT), which is related with brittleness. So, it is crucial to accurately predict both PCT and MCT during entire storage period. The cladding temperature is primarily influenced by decay heat and ambient conditions. The lifetime PCT may occur during summer at the beginning of storage, while the lifetime MCT occurs during winter at the end of storage. In this study, we calculated the PCT and MCT during the entire storage period using a realistic thermal analysis model and, subsequently, conducted their uncertainty analysis.

In this paper, a new type of wind collection device that can generate rotating wind for wind power generation has been designed to address the shortcomings of current wind power generation devices. This device can collect wind energy from different directions by changing the direction of the wind. Firstly, the simulation model for this wind collection device had been designed by the software SolidWorks. Secondly, the internal flow field of the model was modeled and simulated using Computational Fluid Dynamics, and the k-ω SST model was selected in Fluent for flow field analysis. The results showed that this device could generate an outlet wind speed of 3.8 m/s at a wind speed of 4 m/s, which verified the wind collection effect of the device. Thirdly, the outlet wind speed was taken as the optimization objective, and orthogonal optimization design was carried out on the guide convex groove in the model, and the optimal design parameters of the guide convex groove were determined. The results showed that when the width of the diversion convex groove is 47.35mm and the height is 10.65mm, the outlet wind speed is the highest, about 3.89m/s. Finally, to verify the analysis results of numerical simulation, the experimental verification of the wind collection device was carried out through physical prototypes. The results indicated that the simulation results are consistent with the physical results The design of this device can provide theoretical support for the subsequent design of a full-direction wind collection device to cope with the complex wind direction conditions.

Dentre as diversas fontes renováveis de energia que podem ser exploradas, têm-se a energia contida nas ondas do mar. A metodologia WaveMIMO é utilizada para a geração numérica de ondas irregulares baseadas em estados de mar realísticos e consiste em tratar dados espectrais para a obtenção de perfis de velocidade orbital de propagação das ondas, que são impostos como condição de contorno (CC) em um canal de ondas numérico. Nesse sentido, o presente estudo avalia parâmetros para a aplicação desta metodologia, onde se investigou a discretização da região de imposição da CC de velocidade prescrita, a sensibilidade de malha na região da superfície livre, o passo de tempo empregado e, por fim, a localização do vetor de velocidades em cada segmento da região de imposição da CC de velocidade prescrita. Para tanto, foram considerados dados realísticos referentes a um ponto próximo à costa do município de Mostardas, no estado do Rio Grande do Sul, obtidos do modelo espectral TOMAWAC. Os resultados indicaram que, comparando o melhor e o pior caso avaliado, obteve-se melhorias de 6,58% e 7,60% nas métricas consideradas nas avaliações dos resultados.

In our work, experimental tests were conducted to study the hydraulic jump's characteristics forming in a flume with rectangular cross section. A broad crested weir with one step is used to produce a hydraulic jump downstream the flume. A 2D ANSYS-Fluent model version 20, which is a powerful tool used to simulate hydraulic problems with complex geometry, was used. Volume of fluid (VOF) method with a (k--ε) realizable turbulent model was applied to simulate the hydraulic jump for different flow conditions. After validating the numerical model with experimental data, it was then used to calculate sequent depths and velocity contours and to predict the location of the hydraulic jump formed in the flume. Different tail water depths were produced for different flowrate values by adjusting the opening of the tail gate located at the end of the channel. The water surface profiles obtained from the numerical model were in good agreement with those obtained using the physical model, as confirmed by a statistical analysis employing some standard error indexes. Thus, the numerical model can effectively estimate the hydraulic jump location. Results showed that the distance to hydraulic jump increases as the sequent depth decreases due to increasing tail gate opening. For most flow conditions, the depth of the tail water is slightly lower than the sequent depth. The relative height of the hydraulic jump located near the downstream was low and had shorter roller lengths than that located near the weir. Therefore, it is classified as undular jump. Some relations between studied variable are presented in the following section. [ABSTRACT FROM AUTHOR]

The gears in the high-speed heavy-duty gearbox of the high-speed train are typical high-speed heavy-duty gears. Combined with the transmission principle and structural characteristics of the high-speed train drive gearbox, to ensure adequate lubrication of meshing gears and bearings, an optimization of the lubricating oil flow inside the gearbox was conducted. The oil and gas two-phase flow model inside the gearbox adopts the VOF model, and the turbulence model adopts the standard model. Fluent is used for simulation calculation. The results show that the exhaust port position of the gearbox has little effect on the flow of lubricating oil inside the gearbox; the overall pressure distribution inside the gearbox is relatively uniform, with higher pressure only at the meshing gears; the distribution of lubricating oil inside the gearbox is related to the rotation of the gears, and the flow velocity of lubricating oil is mainly affected by the rotation of the gears, with the maximum flow velocity appearing around the gears; the flow of lubricating oil inside the gearbox meets the lubrication requirements of the gearbox. These results provide support for the lubrication design, flow channel structure improvement, and effectiveness evaluation of high-speed train transmission gearboxes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Objective] To improve the automation level of 0the temperature control of grain cooling. [Methods] Using SST k-ω turbulence model and non-equilibrium thermal model to conduct theoretical analysis. Fluent was used for simulation and combined with process validation to explore the temperature distribution law during the process of grain spreading and cooling, and to optimize the spreading and cooling process via Univariate analysis and multivariate orthogonal analysis. Based on the degree how the discharge temperature meets the process requirements, and analyzed the impact of the thickness of the grain layer, the speed of the plate chain movement, and the impact of the exhaust air volume on the air flow distribution, temperature field distribution, and the temperature changes during the entire grain movement process. [Results] After analysis, it was found that the thickness of the material layer has significant impact on the discharge temperature, the speed of the plate chain movement and the exhaust air volume have secondary impacts. The relationship equations between the discharge temperature and the grain residue processing capacity, and exhaust air volume were determined, which were convenient for predicting the discharge temperature in case of process changes. [Conclusion] Through process verification, the non-equilibrium thermal simulation method is accurate and effective in simulating the spreading and cooling process. The optimal process conditions for this spreading and cooling machine are about 20 cm in thickness of grain, 0.15 m/s in plate chain movement and 5 000 m3/h exhaust air volume. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ordnance Equipment Engineering is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Urban green spaces (UGSs) are considered an important natural approach for improving urban climatic conditions, promoting sustainable urban development, and advancing the global "Carbon Peak and Carbon Neutrality" targets. Previous studies have found that different vegetation spatial morphologies significantly impact the capacity to obstruct and absorb CO2, but it is not yet well understood which morphology can retain and absorb more CO2. This study takes Nantong Central Park as an example and conducts a CFD (Computational Fluid Dynamics) carbon flow simulation for CO2 under different vegetation spatial morphologies to identify their CO2 retention and absorption effects. First, the carbon sink benefits of elements such as "vegetation, soil, and wetlands" within the park were calculated, and the elements with the highest carbon sink benefits were identified. Then, the park was divided into carbon welcoming zones, carbon flow zones, and carbon shadow zones for carbon flow simulation with the highest carbon sink benefits. The results show that in the carbon welcome area, the one-block long fan-shaped plant community with a spatial density of 40 m thickness can best meet the requirements of absorption and induction of a small amount of carbon dioxide, with the smallest air vortex and uniform distribution of carbon dioxide in the surrounding area. In the carbon flow area, combined with the visual effect, the planting pattern of 6 m spacing herringbone combined with natural structure was adopted, which has a good carbon dioxide blocking and absorption capacity. In the carbon-shaded area, a herringbone planting pattern with a total width of 40 m and a base angle of 60° was chosen, which had the strongest hindrance and absorption capacity. Urban park environment optimization can use Fluent simulation to analyze the flow of carbon dioxide between different elements affected by wind dynamics at the same time. Based on the results, the form, layout, and spatial distance are adjusted and optimized. This study can better guide the spatial layout of vegetation and contribute to the realization of the goal of "carbon peak and carbon neutrality". [ABSTRACT FROM AUTHOR]

This study focuses on how fonts selected from different families have been used to test for disfluency. The motivation and standard for choosing a particular font for an experiment are not yet clearly defined from past studies. Drawing on methods in a systematic review of 10 articles published between 2007 and 2020, this article shows that authors prefer to use sans serif fonts in fluent conditions and serifs, scripts or handwritten fonts in disfluent conditions. In this study, disfluency manipulations were limited to reducing font sizes and percentages of grey or black. The largest size used was 56pt (fluent) and 18pt (disfluent) while the smallest was 12pt (fluent) and 10pt (disfluent). We observed that the opacity values of disfluent fonts ranged between 10% and 60%, making it unclear how disfluent a font can be. Apart from font sizes, fixation time, familiarity with materials and other controls influenced the results. This article reveals that a major gap still exists in research because of a lack of standard methods for determining the fonts used for testing subjects.

Dust concentration in coal mine roadways significantly affects worker safety and health. Effective dust control is critical for optimizing the mine ventilation system and creating a safer working environment. This study investigates the impact of ventilation duct arrangements on dust concentration in a heading face, aiming to identify the optimal configurations for minimizing dust levels and enhancing worker safety. Using numerical simulations based on the gas-solid two-phase flow model in Fluent, we analyzed the effects of varying duct outlet distances and heights on airflow patterns and dust dispersion. Mesh generation, grid independence verification, and detailed parameter settings ensured accuracy and reliability of the simulation results. Results indicate that positioning the duct outlet 8 m from the heading face reduces dust concentration to approximately 39 mg/m³, while setting the duct height at 1.5 m notably decreases dust levels in the worker breathing zone. A mesh density of 576,449 cells ensured convergence and computational efficiency with an error margin within 2%. The findings provide practical insights into ventilation system optimization for coal mine heading faces, contributing to improved occupational health and operational safety. Future research should focus on validating these results through field experiments and addressing complex real-world conditions.

Fluidized beds are pivotal in the process industry and chemical engineering, with Computational Fluid Dynamics (CFD) playing a crucial role in their design and optimization. Challenges in CFD modeling stem from the scarcity or inconsistency of experimental data for validation, along with the uncertainties introduced by numerous parameters and assumptions across different CFD codes. This study navigates these complexities by comparing simulation results from the open-source MFIX and OpenFOAM, and the commercial ANSYS FLUENT, against experimental data. Utilizing a Eulerian–Eulerian framework and the kinetic theory of granular flow (KTGF), the investigation focuses on solid-phase properties through the classical drag laws of Gidaspow and Syamlal–O’Brien across varied parameters. Findings indicate that ANSYS Fluent, MFiX, and OpenFOAM can achieve reasonable agreement with experimental benchmarks, each showcasing distinct strengths and weaknesses. The study also emphasizes that both the Syamlal–O’Brien and Gidaspow drag models exhibit reasonable agreement with experimental benchmarks across the examined CFD codes, suggesting a moderated sensitivity to the choice of drag model. Moreover, analyses were also carried out for 2D and 3D simulations, revealing that the dimensional approach impacts the predictive accuracy to a certain extent, with both models adapting well to the complexities of each simulation environment. The study highlights the significant influence of restitution coefficients on bed expansion due to their effect on particle–particle collisions, with a value of 0.9 deemed optimal for balancing simulation accuracy and computational efficiency. Conversely, the specularity coefficient, impacting particle–wall interactions, exhibits a more subtle effect on bed dynamics. This finding emphasizes the critical role of carefully choosing these coefficients to effectively simulate the nuanced behaviors of fluidized beds.

Turbulent backward step flow, including air and copper nanoparticles, has been simulated using the Computational Fluid Dynamics (CFD) method by the Eulerian-Lagrangian method. The simulation was done using two- and three-dimensional methods with CFX and FLUENT software. The obtained results were compared with each other and with the experimental results. The two-way coupling discrete phase model (DPM) was used for simulation. The Saffman lift force, pressure gradient, and turbulence effects on nanoparticles are considered. Numerical results obtained with Eulerian-Lagrangian models and single-phase models in steady and transient have been compared with experimental data. The effect of the turbulence model on the trajectory of particles and in terms of different diameters of 10, 20, 30, 50, 70, 100, and 200 micrometers have been investigated. The effects of particle diameter on the trajectory and behavior of particles and the effect of Stokes number on the presence of particles in the vortex created behind the step have been investigated. The results have been presented as various contours and graphs for two- and three- dimensional, steady, and transient states. Particle trajectories are shown as contours for different Stokes numbers and particle diameters. The continuous phase velocity variation across the channel for different distances of step are presented as graphs. Standard, RNG, and Realizable k-e and standard and SST k-w models are considered for the modeling of turbulent flow. The results show that SST k-w is more accurate than the experimental data. Furthermore, simulation was done using CFX software. Variations of velocity profile are compared with experimental and Fluent data. The results show that the Stokes number and the turbulence model have a significant effect on the trajectory of particles. Three-dimensional modeling of the flow increases the accuracy of the results. The maximum error in the single-phase method is equal to 25% and for the Eulerian-Lagrangian method is equal to 19%. Particles with a Stokes number smaller than 1.2 (equivalent to a diameter of 35 micrometers in this study) sense the presence of the vortex and enter the vortex. Among the turbulence models, the lowest error for the sst model is equal to 6.25, and the highest error for the standard Kε model is equal to 18.75.

The water jet nozzle is a penetrating drilling tool, which sends the pumped water to the nozzle through a high-pressure hose. It can work in a variety of working environments. When it dredges the blockage in the pipeline, its structural parameters will affect the jet flow field in the pipeline. Taking the self-propelled water jet nozzle as the research object, SolidWorks was used to establish the nozzle model with different parameter structures. Based on Fluent, the k-ε turbulence model was used to simulate the jet of nozzles with different nozzle sizes and arrangements in the pipeline. The distribution of the jet flow field and the change in velocity and displacement of nozzles with different parameters in the pipeline were compared, and then computational fluid dynamics (CFD) were used to process the simulation data for further research. The results show that when the inclination angle of the rear nozzle is 35°, the attenuation of the front jet velocity and the fluctuation of the wall fluid velocity are the smallest. When the nozzle aperture is increased from 2 mm to 3.5 mm, the vortex area inside the pipe is reduced, and the velocity attenuation of the front jet is also reduced, with the velocity attenuation rate decreasing by about 10%. This study provides a reference for the design and parameter optimization of self-propelled water jet nozzles. [ABSTRACT FROM AUTHOR]

This study employs pinch analysis to optimize the performance of multi-stage micro heat exchangers (MHEs) in industrial applications. The research pinpoints crucial pinch points that optimize heat transfer potential and employs advanced computational fluid dynamics (CFD) simulations to forecast flow patterns and temperature profiles. The analysis emphasizes comprehensive design considerations and provides actionable guidelines to enhance the performance and sustainability of MHEs across various industrial applications. Key findings include that tubes with a 2 mm diameter exhibit higher heat exchange efficiency compared to those with a 3 mm diameter, and the optimal pipe spacing for heat exchange efficiency is 7.5 mm. These results are validated through HYSYS-generated pinch analysis charts, revealing economic benefits for specific tube diameters and spacing's. The strain contrast improved for the 5 mm pipe separating line. The pipe diameter of 2 mm showed lower convergence between hot and cold composite curves, suggesting economic benefits for 2 mm heat exchangers. The pinch point hot and cold temperatures were 54.65, 41.58, and 35.46 degrees Celsius, respectively. [ABSTRACT FROM AUTHOR]

The aim of the present work is to investigate the performance indication and flow of a counter heat device using different baffle configurations numerically. This research illustrates the consequence of segmental stumps and wavy cross-section stumps with varying wave numbers and amplitude. The governing equations of energy and Navier-Stokes equations were solved using the Computational Fluid Dynamics (CFD) software package FLUENT 22R1, employing the finite volume method. The SIMPLE algorithm with second-order upwind discretization for the convection term was used for velocity and pressure calculations. Different cold water rates of flow (2, 4, 6, and 8 L/min) at 23℃ through shell and Constand hot water flow rate at 1 LPM at 50℃ were analysed for their effect on heat transfer efficiency. The heat exchanger's thermal performance was comparing its duty with various baffle configurations to its performance without baffle. The research results indicate that installing baffles increased the heat exchanger's effectiveness (ε)., with the enhancement ratio (ε/εNE) reaching 1.2 and 1.23 for segmental and wavy baffles respectively compared to no baffle. On the other hand, the overall heat transfer coefficient (Uo) showed an improvement with baffles, achieving a performance increase of up to 1.38 at 8 LPM for Wavy baffles with wave number and amplitude (15 and 3 mm) respectively. The pressure drop in the system increased to 406 Pa at wavy baffles (15 and 3 mm) of 6 LPM. The maximum amount of exergy destruction being approximately 0.29 at 8 LPM for segmental. The results providing insights into optimal baffle design for specific applications. [ABSTRACT FROM AUTHOR]

Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Light Industry Machinery is the property of Light Industry Machinery Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aerated irrigation is an emerging and efficient irrigation technique, and the throttle-squeeze releaser (TS releaser) is a commonly used key component in aerated irrigation devices. However, it has issues such as large bubble size, uneven distribution, and low dissolved-oxygen content in the irrigation water. Given these problems, this study optimized the valve chamber and throat structure of the releaser based on the TS releaser, designing three different types of releasers with W-shaped valve chamber, arc-shaped valve chamber, and multi-throat W-shaped valve chamber. The simulation results, obtained using the Fluent module with grid division in ANSYS 2022, show that high-pressure regions are formed inside the releaser with V-shaped and arc-shaped valve chambers that are detrimental to the formation of microbubbles in high-pressure dissolved-air water, while the fluid pressure reduction and energy dissipation are more balanced inside the releasers with a W-shaped valve chamber. Compared to a single-throat design, the multi-throat design allows high-pressure fluid to enter the valve chamber more uniformly, which aids in maximizing the functionality and performance of the valve chamber. To determine the effects of throat size, outlet size, and valve chamber angle on the pressure field, turbulent flow field, velocity field, and air-phase distribution within the multi-throat W-shaped valve chamber releaser, simulation interaction experiments were conducted. The results showed that the optimized releaser performed best when the throat diameter was 1 mm, the outlet size was 2 mm, and the valve chamber angle was 80°. Finally, a comparative performance evaluation between the conventional TS diffuser and the optimized multi-throat W-valve chamber releaser reveals that the latter achieves a maximum dissolved-oxygen content of 6.36 mg/L in the treated irrigation water, representing an approximately 3.5% improvement over the 6.14 mg/L recorded by the traditional releaser. Furthermore, when considering the thresholds of irrigation flow rates above 950 L/h and dissolved-oxygen levels exceeding 5.9 mg/L, the multi-throat W-valve chamber diffuser exhibits a broader operational range characterized by high flow rates and dissolved-oxygen levels. [ABSTRACT FROM AUTHOR]

To improve the force endurance capacity of plate breakwaters, a step‐type plate breakwater was proposed. The performance of the step‐type breakwater was investigated by numerical simulation method. First, a two‐dimensional numerical regular wave tank was constructed using FLUENT software, and the effectiveness of the tank application was verified by comparing with theoretical value and test data. Then, the numerical tank was used to simulate various working conditions, and the variation rules of the breakwater transmission coefficient with wave height, period, perforation rate, relative plate width, wave steepness, and number of layers were obtained. Finally, the difference in the wave dissipation mechanism between the step‐type breakwater and the ""‐type breakwater was discussed. The results indicated that the transmission coefficient of the step‐type breakwater was small, which also proved to be good at dissipating long‐period waves. In general, the wave dissipation performance of the step‐type breakwater was better than that of the ""‐type breakwater. The research can provide some clues for the research and design of corresponding breakwaters. [ABSTRACT FROM AUTHOR]

The development of more environment-friendly ways to dispose of oil sludge is currently regarded as a hot topic. In this context, gasification technologies are generally seen as a promising way to combine oil sludge with coal–water slurry (CWS) and generate resourceful fuel. In this study, a novel five-nozzle gasifier reactor was analyzed by means of a CFD (Computational fluid dynamic) method. Among several influential factors, special attention was paid to the height-to-diameter ratio of the gasifier and the mixing ratio of oil sludge, which are known to have a significant impact on the flow field, temperature distribution and gasifier performances. According to the numerical results, the optimal height-to-diameter ratio and oil mixing ratio are about 2.4:1 and 20%, respectively. Furthermore, the carbon conversion rate can become as high as 98.55% with the hydrolysis rate reaching a value of 53.88%. The consumption of raw coal and oxygen is generally reduced, while the effective gas production is increased to 50.93 mol/%. [ABSTRACT FROM AUTHOR]

To address the challenges of indoor mold in southern China, this study designed and constructed an innovative experimental system to investigate mold growth in buildings under the combined influence of multiple factors. Using Fluent simulation (Ansys Fluent 19.0), we designed a suitably sized experimental chamber to realistically replicate the effects of factors such as temperature, humidity, and air velocity on mold growth. After establishing and fine-tuning the experimental system, we conducted two preliminary experiments, successfully validating the feasibility of our setup. Additionally, we observed that in a high-temperature, high-humidity environment of 28 °C and 80% relative humidity, the mold growth rate in the experimental chamber increased with the rise in inlet air velocity. This experimental system will serve as the foundation for future studies on indoor mold growth in building spaces in southern China. [ABSTRACT FROM AUTHOR]

After a highway tunnel fire, the rapid change of the internal ambient temperature directly affects the personal safety of pedestrians. Based mainly on the lateral possibility of fire location and considering the coupling effect of multiple factors in a two‐lane highway tunnel, this study systematically carried out 63 full‐size tunnel fire simulation studies relying on Fluent software. The smoke temperature distribution patterns in the transverse and longitudinal spaces of the tunnel after the fire were revealed. This study shows that the smoke temperature below the tunnel vault is susceptible to the effect of sidewall restraint, making the maximum temperature of the tunnel vault of the offset fire source large; considering the lateral location of the fire source, the maximum temperature prediction formula of the tunnel vault is modified to expose the change law of the longitudinal temperature decay of the vault. This paper reveals for the first time the law of temperature distribution changes at the characteristic height of the human eye on the evacuation platform in the tunnel; the systematic study of the fire source cross‐sectional temperature distribution changes at the key lining structure points, and it is found that a low‐temperature space conducive to personnel escape exists in the lower part of the tunnel away from the fire source side. The results of the study are beneficial to the design of safe evacuation paths in the tunnel and the active emergency evacuation of personnel in the near‐fire source area. [ABSTRACT FROM AUTHOR]

Fluidized beds are pivotal in the process industry and chemical engineering, with Computational Fluid Dynamics (CFD) playing a crucial role in their design and optimization. Challenges in CFD modeling stem from the scarcity or inconsistency of experimental data for validation, along with the uncertainties introduced by numerous parameters and assumptions across different CFD codes. This study navigates these complexities by comparing simulation results from the open-source MFIX and OpenFOAM, and the commercial ANSYS FLUENT, against experimental data. Utilizing a Eulerian–Eulerian framework and the kinetic theory of granular flow (KTGF), the investigation focuses on solid-phase properties through the classical drag laws of Gidaspow and Syamlal–O'Brien across varied parameters. Findings indicate that ANSYS Fluent, MFiX, and OpenFOAM can achieve reasonable agreement with experimental benchmarks, each showcasing distinct strengths and weaknesses. The study also emphasizes that both the Syamlal–O'Brien and Gidaspow drag models exhibit reasonable agreement with experimental benchmarks across the examined CFD codes, suggesting a moderated sensitivity to the choice of drag model. Moreover, analyses were also carried out for 2D and 3D simulations, revealing that the dimensional approach impacts the predictive accuracy to a certain extent, with both models adapting well to the complexities of each simulation environment. The study highlights the significant influence of restitution coefficients on bed expansion due to their effect on particle–particle collisions, with a value of 0.9 deemed optimal for balancing simulation accuracy and computational efficiency. Conversely, the specularity coefficient, impacting particle–wall interactions, exhibits a more subtle effect on bed dynamics. This finding emphasizes the critical role of carefully choosing these coefficients to effectively simulate the nuanced behaviors of fluidized beds. [ABSTRACT FROM AUTHOR]

Modern laver fluffiness is achieved by applying high-speed gas to a laver, which is generated by the opening and closing of a laver fluffiness control valve in a fluffiness system. To address the problems of the slow response speed and poor stability of valves used in the laver processing industry at present, this paper proposes a novel principle of a high-speed switching control valve, which has the advantages of a fast response speed, high stability, and long service life. The structure and working principle of the control valve are introduced, and the calculation equation of the valve's flow area is established. The flow field inside the control valve with different openings was numerically calculated in this study using Fluent. The flow regulation characteristics and flow field performance of the control valve were also analyzed. The results show that, with an increase in the valve opening, the influence of the flow area at the valve throttle on the valve flow rate was weakened. When the valve was opened, a vortex appeared in both the upper and lower cavities, and jet flow occurred at the throttle of the middle flow channel. As the valve opening increased, the pressure in the upper cavity reduced, while the pressure in the lower cavity increased. The vortex in the flow field intensified, and the jet phenomenon at the valve throttle gradually disappeared. At the same time, the main stream in the lower cavity gradually changed from an annular flow to a direct flow toward the valve outlet. Furthermore, the impact, collision, and vortex formation of the fluid caused energy loss of the fluid, leading to a decrease in the outlet flow of the control valve. [ABSTRACT FROM AUTHOR]