Browse
Keywords
Records with Keyword: Computational Fluid Dynamics
Showing records 448 to 472 of 641. [First] Page: 1 15 16 17 18 19 20 21 22 23 Last
Study of the Blade Shape Impact on the Improvement of Fan Efficiency Based on State-of-the-Art Prototyping Methods
Michał Szelka, Andrzej Drwięga, Jarosław Tokarczyk, Marek Szyguła, Kamil Szewerda, Marian Banaś, Krzysztof Kołodziejczyk, Krzysztof Kędzia
February 24, 2023 (v1)
Keywords: 3D printing, axial fan, Computational Fluid Dynamics, efficiency, FEM, rapid prototyping, ventilation
The article discusses the process of designing and testing as well as their results, carried out in order to increase the efficiency of axial fans, implemented as part of the European project INESI. Modifications of existing solutions based on rapid prototyping methods were presented. Scanning, FEM and CFD numerical calculations and 3D printing were used for that purpose. Rapid prototyping involved the use of a steel blade base and 3D-printed complex aerodynamic shapes that were bonded to create completely new blades. After their installation on the new rotor, enabling the angle of attack adjusting, a number of verifying tests of the fan were carried out. The solution was successfully tested and the results are discussed in the article.
A Numerical Procedure for Variable-Pitch Law Formulation of Vertical-Axis Wind Turbines
Cinzia Rainone, Danilo De Siero, Luigi Iuspa, Antonio Viviani, Giuseppe Pezzella
February 24, 2023 (v1)
Keywords: Computational Fluid Dynamics, variable-pitch law, vertical-axis wind turbine, wind energy
A numerical procedure was developed to determine a variable-pitch law that maximized the performance of a vertical-axis wind turbine (VAWT). The methodology was based on the determination, for each blade, of the angle of attack maximizing the stationary aerodynamic efficiency at prescribed azimuthal positions. The angles of attack were determined by means of a panel method with a low computational effort, and the methodology was implemented in Matlab® software (version R2021a) allowing us to achieve in real time a variable-pitch law suitable for the turbine geometry. The variable pitch law was validated by considering its effect on the torque of a 2D model of an H-Darrieus turbine. U-RANS analyses were carried out with a K−ωSST model and a sliding-mesh technique was used to prescribe the blade motion around the shaft and pitch motion. Results showed how the variable-pitch law delayed the dynamic stall and improved the aerodynamic performance considerably.
Application of Intelligent and Digital Technologies to the Tasks of Wind Energy
Vladislav N. Kovalnogov, Ruslan V. Fedorov, Andrei V. Chukalin, Mariya I. Kornilova, Tamara V. Karpukhina, Anton V. Petrov
February 24, 2023 (v1)
Keywords: atmospheric boundary layer, Computational Fluid Dynamics, intelligent system, mathematical modeling, wind farm
The article considers the relevance and issues of wind turbine modeling, the principles of wind energy conversion (WEC) system operation, working areas and regulation. The influence of soft computing technologies on the different aspects of wind power systems, particularly in the fields of operation and maintenance, is considered. This article discusses the recent research, development and trends in soft computing techniques for wind-energy-conversion systems. For reliable analysis, the interaction of the wind-generator operation with the atmospheric boundary layer is considered. The authors give a detailed description of the approaches for the study and numerical modeling of the atmospheric boundary layer (ABL) in the vicinity of a wind farm. The study of the atmospheric boundary layer in the vicinity of the Ulyanovsk wind farm on the basis of cluster analysis of meteorological data is performed. Ten localizations of ABL homogeneous properties are identified. The subject of the study... [more]
Research on Air Distribution Control Strategy of Supercritical Boiler
Yingai Jin, Yanwei Sun, Yuanbo Zhang, Zhipeng Jiang
February 24, 2023 (v1)
Keywords: air distribution, Computational Fluid Dynamics, control strategy, supercritical boiler
Supercritical boilers have become a major development trend in coal-fired power plants, and the air distribution strategy is a key factor in the design and operation of making it fully combustible. In this paper, the mathematical and physical models of a 350 MW supercritical boiler is established, and the optimal air distribution mode of the boiler at different load is determined based on the furnace outlet temperature, NOx concentration, and O2 content. The air distribution control strategies were derived and the corresponding procedures were established. 160 MW and 280 MW were selected for positive pagoda and 180 MW and 230 MW for waist reduced. At 290−350 MW load, the effect of adjusting the combustion damper opening on the outlet oxygen is weak, so preferentially adjusting the SOFA damper opening can achieve better results. The results show good thermal efficiency and emission performance and are applicable to adjust the air distribution mode to achieve fuller combustion of supercr... [more]
Experimental and Computational Analysis of Aluminum-Coated Dimple and Plain Tubes in Solar Water Heater System
Debabrata Barik, Arun M., Muhammad Ahsan Saeed, Tholkappiyan Ramachandran
February 24, 2023 (v1)
Keywords: aluminum-coated tube, Computational Fluid Dynamics, parabolic trough solar collector, plain tube, solar energy
Solar power is often regarded as one of the most promising forms of alternative energy since it is both sustainable and renewable. It is difficult to utilize and benefit from solar energy in residential and industrial applications because of the intermittent nature of its supply. A solar-based water heating system is efficient for using solar thermal conversion, the simplest and most successful method of turning solar energy into thermal energy. In this research, the performance analysis of Parabolic Trough Solar Collectors (PTSCs) with aluminum-coated copper dimple tubes was computationally and experimentally analyzed. For computational analysis, a Computational Fluid Dynamics (CFD) tool was used. For experimental analysis, aluminum-coated dimple tubes were used to pass the base fluid (water) in it while varying the mass flow rate from 1.0 to 3.0 kg/min at steps of 0.5 kg/min to examine the effect of dimple texturing and aluminum coating on the performance of the solar water heater. T... [more]
CFD Calculations of Average Flow Parameters around the Rotor of a Savonius Wind Turbine
Jan Michna, Krzysztof Rogowski
February 24, 2023 (v1)
Keywords: Computational Fluid Dynamics, RANS, Savonius, turbulence, VAWT, wind turbine
The geometry of a conventional two-bladed Savonius rotor was used in this study based on a report available in the literature. A two-dimensional rotor model consisting of two buckets and an overlap ratio of 0.1 was prepared. The unsteady Reynolds averaged Navier-Stokes (URANS) equations and the eddy-viscosity turbulence model SST k-ω were employed in order to solve the fluid motion equations numerically. Instantaneous velocities and pressures were calculated at defined points around the rotor and then averaged. The research shows that the operating rotor significantly modifies the flow on the downwind part of the rotor and in the wake, but the impact of the tip speed ratio on the average velocity distribution is small. This parameter has a much greater influence on the characteristics of the aerodynamic moment and the distribution of static pressure in the wake. In the upwind part of the rotor, the average velocity parallel to the direction of undisturbed flow is 29% lower than in the... [more]
Influence of the Longitudinal and Tree-Shaped Fin Parameters on the Shell-and-Tube LHTES Energy Efficiency
Grzegorz Czerwiński, Jerzy Wołoszyn
February 24, 2023 (v1)
Keywords: Computational Fluid Dynamics, Energy Efficiency, LHTES, multi-objective optimisation, numerical simulation, phase change material, sensitivity analysis, thermal energy storage
Changes in the energy sector, associated with the move away from fossil fuels, pose a challenge for appropriate thermal energy management in residential buildings. The important element to deal with the variability of renewable energy in thermal systems is latent heat thermal energy storage. Due to the low thermal conductivity of phase change materials, a number of techniques are proposed to enhance the heat transfer process. In this research, the global sensitivity of fin geometrical parameters on the melting and solidification times and energy efficiency of these processes was investigated. The computational model of the phase change was developed using the finite volume method with the enthalpy-porosity model and Boussinesq approximation. Numerical simulations were carried out according to the design of experiments technique. The multi-dimensional response surface was developed, and the multi-objective optimisation was done. The research shows that the melting process is most influe... [more]
Computational Fluid Dynamics for Protonic Ceramic Fuel Cell Stack Modeling: A Brief Review
Anitha Dhanasekaran, Yathavan Subramanian, Lukman Ahmed Omeiza, Veena Raj, Hayati Pg Hj Md Yassin, Muhammed Ali SA, Abul K. Azad
February 23, 2023 (v1)
Keywords: Computational Fluid Dynamics, design optimization, oxygen-ion conducting fuel cells, physical processes, protonic ceramic fuel cells
Protonic ceramic fuel cells (PCFCs) are one of the promising and emerging technologies for future energy generation. PCFCs are operated at intermediate temperatures (450−750 °C) and exhibit many advantages over traditional high-temperature oxygen-ion conducting solid oxide fuel cells (O-SOFCs) because they are simplified, have a longer life, and have faster startup times. A clear understanding/analysis of their specific working parameters/processes is required to enhance the performance of PCFCs further. Many physical processes, such as heat transfer, species transport, fluid flow, and electrochemical reactions, are involved in the operation of the PCFCs. These parameters are linked with each other along with internal velocity, temperature, and electric field. In real life, a complex non-linear relationship between these process parameters and their respective output cannot be validated only using an experimental setup. Hence, the computational fluid dynamics (CFD) method is an easier... [more]
Effect of the Design Parameters of the Combustion Chamber on the Efficiency of a Thermal Oxidizer
Quang Hat Cao, Sang-Wook Lee
February 23, 2023 (v1)
Keywords: combustion efficiency, Computational Fluid Dynamics, eddy dissipation model, non-premixed combustion, stack height, volatile organic compounds burner
Carbon monoxide is often produced during the incomplete combustion of volatile organic carbon compounds in industry. In the combustion chamber for oxidizing carbon monoxide emissions, a penta-coaxial port device can be used to improve the process of mixing the fuel and oxidizer. In this study, the conjugate heat transfer analysis was conducted by solving both Reynolds-averaged Navier−Stokes equations with the eddy dissipation model and solid heat conduction equation in the wall using Fluent 2019R2 to simulate the reaction flow of a volatile organic carbon compound burner and heat transfer of the stack insulation layer. The mass fractions of the O2, CO2, and CO gases; the temperature; and the velocity distribution in a combustion chamber were computed to investigate how various design parameters of the combustor, including air inlet size and stack height, and air inflow conditions affected the combustion performance. Results show that the size of the air inlet had only a minor effect on... [more]
Numerical Investigation of the Initial Charging Process of the Liquid Hydrogen Tank for Vehicles
Daehoon Kang, Sungho Yun, Bo-kyong Kim, Jaewon Kim, Gildong Kim, Hyunbae Lee, Sangyeol Choi
February 23, 2023 (v1)
Keywords: charging, Computational Fluid Dynamics, filling, insulation, liquid hydrogen, phase-change model
Liquid hydrogen has been studied for use in vehicles. However, during the charging process, liquid hydrogen is lost as gas. Therefore, it is necessary to estimate and reduce this loss and simulate the charging process. In this study, the initial charging process of a vehicle liquid hydrogen tank under room temperature and atmospheric pressure conditions was numerically investigated. A transient thermal-fluid simulation with a phase-change model was performed to analyze variations in the volume, pressure, mass flow rate, and temperature. The results showed that the process could be divided into three stages. In the first stage, liquid hydrogen was actively vaporized at the inner wall surface of the storage tank. The pressure increased rapidly, and liquid droplets were discharged into the vent pipe during the second stage. In the third stage, the mass flow rates of liquid and hydrogen gas at the outlet showed significant fluctuations, owing to complex momentum generated by the evaporatio... [more]
Comparative Analysis of Numerical Methods for Simulating N-Heptane Combustion with Steam Additive
Andrey V. Minakov, Viktor A. Kuznetsov, Artem A. Dekterev, Igor S. Anufriev, Evgeny P. Kopyev, Sergey V. Alekseenko
February 23, 2023 (v1)
Keywords: combustion model, Computational Fluid Dynamics, liquid fuel combustion, RANS, superheated steam
Currently, thermal power plants operating on hydrocarbon fuels (gas, fuel oil, peat, shale, etc.) are one of the main sources of electricity. An effective and promising method for suppressing harmful emissions (NOx, carbon oxides, soot) from the combustion of fossil fuels is the injection of steam into the combustion chamber. The influence of various mathematical submodels was studied on the accuracy of the numerical simulation of the process of n-heptane combustion in a laboratory burner with steam additive to the reaction zone as a promising chemical engineering method for the disposal of substandard liquid fuels and combustible waste with the production of thermal energy. The problem was solved in a three-dimensional stationary formulation. Systematic verification of these submodels, and a comparison of the results of the calculation with the experimental data obtained were carried out. The comparison with the experimental data was carried out for gas components and temperature dist... [more]
Numerical Analysis of Two-Stage Turbine System for Multicylinder Engine under Pulse Flow Conditions with High Pressure-Ratio Turbine Rotor
Dariusz Kozak, Paweł Mazuro
February 23, 2023 (v1)
Keywords: Computational Fluid Dynamics, efficiency, exhaust system, internal combustion engine, radial turbine, turbocharging, unsteady flow, VTG
Internal combustion engine (ICE) exhaust gases provide a high amount of energy which is partially lost to the environment. Such energy can be recovered with a turbocharger turbine or other after-treatment device. As the engine exhaust flow varies not only with the engine load but also with the opening and closing of the exhaust valves, a proper matching between the engine and the turbine should be established to maximize the recovery of waste energy. That is why a twin-scroll or dual turbocharging system is implemented, especially in multi-cylinder engines. Such systems require a very complex pipeline to eliminate the interference of the exhaust pulses between the adjacent cylinder ignitions. In this study, the two-stage, multi-channel turbine system was investigated for two different rotor geometries: the old, high-performance rotor A and the smaller but more modern rotor B, which was scaled to match rotor A. Both geometries were compared at three different turbine speeds and variable... [more]
Numerical Optimization of Spray-Guided Spark Assistance for Cold Idle Operation in a Heavy-Duty Gasoline Compression Ignition Engine
Le Zhao, Yu Zhang, Yuanjiang Pei, Anqi Zhang, Muhsin M. Ameen
February 23, 2023 (v1)
Keywords: cold operation, Computational Fluid Dynamics, design of experiments, gasoline compression ignition, Optimization, spark assistance
This article describes the results of a response surface model (RSM)-based numerical optimization campaign for spray-guided spark assistance at cold operations in a heavy-duty gasoline compression ignition (GCI) engine. On the basis of an earlier work on spark-assisted GCI cold combustion, a space-filling design of experiments (DoE) method was first undertaken to investigate a multitude of hardware design variables and engine operating parameters. The main design variables included the number of injector nozzles, fuel split quantities and injection timings, and spark timing. The objective variables were engine combustion efficiency (ŋc), maximum pressure rise rate (MPRR), and engine-out nitrogen oxide (NOx) emissions. A total of 150 design candidates were automatically generated using the Sobol sequence method provided by the commercial software package, CAESES. Then, closed-cycle computational fluid dynamic (CFD) spark-assisted GCI simulations under cold idling operations were perform... [more]
Computational Fluid Dynamic Simulation of Leakage Acoustic Waves Propagation Model for Gas Pipelines
Xuejie Li, Yuan Xue, Yuxing Li, Qingshan Feng
February 23, 2023 (v1)
Keywords: acoustic waves, Computational Fluid Dynamics, natural gas pipelines, propagation model
When leakage occurs for natural gas pipelines, acoustic waves generated at the leakage point will propagate to both ends of the pipe, which will be measured and processed to detect and locate the leakage. When acoustic waves propagate in the gas, the amplitude will attenuate and the waveform will spread, which decides the installation distance of acoustic sensors. Therefore, computational fluid dynamic (CFD) simulation research on the acoustic wave propagation model is accomplished and verified by experiments to provide the foundation for the acoustic leak location method. The propagation model includes two parts: amplitude attenuation model and waveform spreading model. Both can be obtained by the established CFD simulation model. Additionally, the amplitude attenuation model can be verified by the experiments. Then, the simulation method is applied to conclude the propagation model under variable conditions, including different flow directions, Reynolds numbers, and diameters. Finall... [more]
Design Challenges in Hydrogen-Fueled Rotary Engine—A Review
Tehseen Johar, Chiu-Fan Hsieh
February 23, 2023 (v1)
Keywords: Computational Fluid Dynamics, hydrogen injection, rotary engine, rotor profile, seal leakage
The rotary engine (RE) is a potential power plant for unmanned aerial vehicles (UAVs) and automobiles because of its structural and design merits. However, it has some serious drawbacks, such as frequent maintenance requirements and excessive fuel consumption. This review paper presents the current status of hydrogen-fueled rotary engine (HRE) technology and identifies the existing research and development gaps in combustion efficiency and performance of this engine that might benefit transportation sector. Focusing primarily on the research from past ten years, the crucial challenges encountered in hydrogen-powered rotary engines have been reviewed in terms of knock, hydrocarbon (HC) emissions, and seal leakages. The paper identifies the recent advances in design concepts and production approaches used in hydrogen-fueled rotary engines such as geometric models of trochoid profiles, port configurations, fuel utilization systems, and currently available computational fluid dynamics (CFD... [more]
Wing Deformation of an Airborne Wind Energy System in Crosswind Flight Using High-Fidelity Fluid−Structure Interaction
Niels Pynaert, Thomas Haas, Jolan Wauters, Guillaume Crevecoeur, Joris Degroote
February 23, 2023 (v1)
Keywords: airborne wind energy, Chimera, Computational Fluid Dynamics, fluid–structure interaction
Airborne wind energy (AWE) is an emerging technology for the conversion of wind energy into electricity. There are many types of AWE systems, and one of them flies crosswind patterns with a tethered aircraft connected to a generator. The objective is to gain a proper understanding of the unsteady interaction of air and this flexible and dynamic system during operation, which is key to developing viable, large AWE systems. In this work, the effect of wing deformation on an AWE system performing a crosswind flight maneuver was assessed using high-fidelity time-varying fluid−structure interaction simulations. This was performed using a partitioned and explicit approach. A computational structural mechanics (CSM) model of the wing structure was coupled with a computational fluid dynamics (CFD) model of the wing aerodynamics. The Chimera/overset technique combined with an arbitrary Lagrangian−Eulerian (ALE) formulation for mesh deformation has been proven to be a robust approach to simulati... [more]
A Proper Shape of the Trailing Edge Modification to Solve a Housing Damage Problem in a Gas Turbine Power Plant
Thodsaphon Jansaengsuk, Mongkol Kaewbumrung, Wutthikrai Busayaporn, Jatuporn Thongsri
February 23, 2023 (v1)
Keywords: aerodynamics, compressor blade, Computational Fluid Dynamics, computer simulation, finite element analysis, gas turbine, housing damage, power plant, structural dynamics, trailing edge
To solve the housing damage problem of a fractured compressor blade (CB) caused by an impact on the inner casing of a gas turbine in the seventh stage (from 15 stages), modifications of the trailing edge (TE) of the CB have been proposed, namely 6.5 mm curved cutting and a combination of 4 mm straight cutting with 6.5 mm curved cutting. The simulation results of the modifications in both aerodynamics variables Cl and Cd and the pressure ratio, including structural dynamics such as a normalized power spectrum, frequency, total deformation, equivalent stress, and the safety factor, found that 6.5 mm curved cutting could deliver the aerodynamics and structural dynamics similar to the original CB. This result also overcomes the previous work that proposed 5.0 mm straight cutting. This work also indicates that the operation of a CB gives uneven pressure and temperature, which get higher in the TE area. The slightly modified CB can present the difference in the properties of both the aerodyn... [more]
Hybrid Approach for Mixing Time Characterization and Scale-Up in Geometrical Nonsimilar Stirred Vessels Equipped with Eccentric Multi-Impeller Systems—An Industrial Perspective
Michael C. Martinetz, Florian Kaiser, Martin Kellner, Dominik Schlosser, Andreas Lange, Michaela Brueckner-Pichler, Cécile Brocard, Miroslav Šoóš
February 23, 2023 (v1)
Keywords: Computational Fluid Dynamics, Computational Fluid Dynamics, conductivity, eccentric impeller position, hybrid approach, mixing time, prediction, stirred vessel, validation
Multipurpose stirring and blending vessels equipped with various impeller systems are indispensable in the pharmaceutical industry because of the high flexibility necessary during multiproduct manufacturing. On the other hand, process scale-up and scale-down during process development and transfer from bench or pilot to manufacturing scale, or the design of so-called scale-down models (SDMs), is a difficult task due to the geometrical differences of used vessels. The present work comprises a hybrid approach to predict mixing times from pilot to manufacturing scale for geometrical nonsimilar vessels equipped with single top, bottom or multiple eccentrically located impellers. The developed hybrid approach is based on the experimental characterization of mixing time in the dedicated equipment and evaluation of the vessel-averaged energy dissipation rate employing computational fluid dynamics (CFD) using single-phase steady-state simulations. Obtained data are consequently used to develop... [more]
Hybrid Approach for Mixing Time Characterization and Scale-Up in Geometrical Nonsimilar Stirred Vessels Equipped with Eccentric Multi-Impeller Systems—An Industrial Perspective
Michael C. Martinetz, Florian Kaiser, Martin Kellner, Dominik Schlosser, Andreas Lange, Michaela Brueckner-Pichler, Cécile Brocard, Miroslav Šoóš
February 23, 2023 (v1)
Keywords: Computational Fluid Dynamics, Computational Fluid Dynamics, conductivity, eccentric impeller position, hybrid approach, mixing time, prediction, stirred vessel, validation
Multipurpose stirring and blending vessels equipped with various impeller systems are indispensable in the pharmaceutical industry because of the high flexibility necessary during multiproduct manufacturing. On the other hand, process scale-up and scale-down during process development and transfer from bench or pilot to manufacturing scale, or the design of so-called scale-down models (SDMs), is a difficult task due to the geometrical differences of used vessels. The present work comprises a hybrid approach to predict mixing times from pilot to manufacturing scale for geometrical nonsimilar vessels equipped with single top, bottom or multiple eccentrically located impellers. The developed hybrid approach is based on the experimental characterization of mixing time in the dedicated equipment and evaluation of the vessel-averaged energy dissipation rate employing computational fluid dynamics (CFD) using single-phase steady-state simulations. Obtained data are consequently used to develop... [more]
Numerically and Experimentally Verified Design of a Small Wind Turbine with Injection Molded Blade
Byunghui Kim, Sang-June Park, Seokyoung Ahn, Myung-Gon Kim, Hyung-Gun Yang, Ho-Seong Ji
February 23, 2023 (v1)
Keywords: Computational Fluid Dynamics, injection molding, small wind turbine, turbulence model, wind tunnel test
Although mega-watt class onshore and offshore wind power systems are used to generate power due to their cost-effectiveness, small wind power systems are important for household usages. Researchers have focused on aerodynamic characteristics as a conceptual design from their previous studies on Archimedes spiral wind turbines. Here, we verified the design of a small wind turbine AWM-750D (100 W capacity) via both numerical simulation and experimentation. We used commercial code ANSYS CFX for numerical simulation and compared turbulence models and surface roughness for determining the performance. To obtain reliable and robust blades, we analyzed the effective manufacturing method with Moldflow. Through a test with an open-suction type atmospheric boundary layer wind tunnel, we varied wind speed from 4.0 m/s to the rated value of 12.5 m/s and obtained 106 W, equivalent to a power coefficient of 0.205. In addition, we compared the numerical and experimental power vs. rotational speed and... [more]
Control of Sunroof Buffeting Noise by Optimizing the Flow Field Characteristics of a Commercial Vehicle
Rongjiang Tang, Hongbin He, Zengjun Lu, Shenfang Li, Enyong Xu, Fei Xiao, Avelino Núñez-Delgado
February 23, 2023 (v1)
Keywords: commercial vehicle, Computational Fluid Dynamics, large eddy simulation, roof dome, sun visor, sunroof buffeting noise
When a commercial vehicle is driving with the sunroof open, it is easy for the problem of sunroof buffeting noise to occur. This paper establishes the basis for the design of a commercial vehicle model that solves the problem of sunroof buffeting noise, which is based on computational fluid dynamics (CFD) numerical simulation technology. The large eddy simulation (LES) method was used to analyze the characteristics of the buffeting noise with different speed conditions while the sunroof was open. The simulation results showed that the small vortex generated in the cab forehead merges into a large vortex during the backward movement, and the turbulent vortex causes a resonance response in the cab cavity as the turbulent vortex moves above the sunroof and falls into the cab. Improving the flow field characteristics above the cab can reduce the sunroof buffeting noise. Focusing on the buffeting noise of commercial vehicles, it is proposed that the existing accessories, including sun visor... [more]
Computational Investigation of Inclusion Removal in the Steel-Refining Ladle Process
Xipeng Guo, Joel Godinez, Nicholas J. Walla, Armin K. Silaen, Helmut Oltmann, Vivek Thapliyal, Abhishek Bhansali, Eugene Pretorius, Chenn Q. Zhou
February 23, 2023 (v1)
Keywords: argon injection, Computational Fluid Dynamics, inclusion removal, multiphase flow, stirring ladle
In a steel-refining ladle, the properties of manufactured steel can be notably degraded due to the presence of excessive inclusions. Stirring via gas injection through a porous plug is often used as part of the steel-refining process to reduce these inclusions. In this paper, 3D computational fluid dynamics (CFD) modeling is used to analyze transient multiphase flow and inclusion removal in a gas-stirred ladle. The effects of gas stirring with bubble-inclusion interaction are analyzed using the Euler−Euler approach for multiphase flow modeling, while the effects of inclusions aggregation and removal are modeled via a population balance model (PBM).
A Eulerian Multi-Fluid Model for High-Speed Evaporating Sprays
Robert Keser, Michele Battistoni, Hong G. Im, Hrvoje Jasak
February 23, 2023 (v1)
Keywords: classes method, Computational Fluid Dynamics, Euler multi-fluid, evaporation, liquid spray, OpenFOAM, temperature profile, validation, WAVE breakup
Advancements in internal combustion technology, such as efficiency improvements and the usage of new complex fuels, are often coupled with developments of suitable numerical tools for predicting the complex dynamic behavior of sprays. Therefore, this work presents a Eulerian multi-fluid model specialized for the dynamic behavior of dense evaporating liquid fuel sprays. The introduced model was implemented within the open-source OpenFOAM library, which is constantly gaining popularity in both industrial and academic settings. Therefore, it represents an ideal framework for such development. The presented model employs the classes method and advanced interfacial momentum transfer models. The droplet breakup is considered using the enhanced WAVE breakup model, where the mass taken from the parent droplets is distributed among child classes using a triangular distribution. Furthermore, the complex thermal behavior within the moving droplets is considered using a parabolic temperature profi... [more]
Effects of Flow Baffles on Flow Profile, Pressure Drop and Classification Performance in Classifiers
Michael Betz, Marco Gleiss, Hermann Nirschl
February 23, 2023 (v1)
Keywords: air classifier, classification performance, Computational Fluid Dynamics, Optimization
This paper presents a study of the use of flow baffles inside a centrifugal air classifier. An air classifier belongs to the most widely used classification devices in mills in the mineral industry, which is why there is a great interest in optimizing the process flow and pressure loss. Using Computational Fluid Dynamics (CFD), the flow profile in a classifier without and with flow baffles is systematically compared. In the simulations, turbulence effects are modeled with the realizable k−ε model, and the Multiple Reference Frame approach (MRF) is used to represent the rotation of the classifier wheel. The discrete phase model is used to predict the collection efficiency. The effects on the pressure loss and the classification efficiency of the classifier are considered for two operating conditions. In addition, a comparison with experimental data is performed. Firstly, the simulations and experiments show good agreement. Furthermore, the investigations show that the use of flow baffle... [more]
Model-Based Prediction of Perceived Light Flashing in Recirculated Inclined Wavy-Bottomed Photobioreactors
Giuseppe Olivieri, Monica Moroni, Marcel Janssen, Luca Piersanti, Daniela Mezza, Marco Bravi
February 23, 2023 (v1)
Keywords: bubble column, cascade photobioreactor, Computational Fluid Dynamics, flashing light effects, flat panel, photobioreactors, spectral analysis, wavy-bottomed photobioreactor
Microalgae biomass production rate in short light-path photobioreactors potentially can be improved by mixing-induced flashing light regimes. A cascade photobioreactor features a thin liquid layer flowing down a sloping, wavy-bottomed surface where liquid flow exhibits peculiar local recirculation hydrodynamics, potentially conducive to an ordered flashing light regime. This article presents a model-based analysis of the frequency distribution of perceived irradiance in said wavy-bottomed photobioreactor. The model combines a Lagrangian description of the motion of individual cells, in turn derived from the hydrodynamic parameters of the photobioreactor extracted from an experimentally validated Computational Fluid Dynamic model, with a simplified description of the irradiance field across the culture thickness, down to the spectral analysis of perceived irradiance. The main finding of the work is that the wavy bottomed photobioreactor provides a ‘robust’ spectral excitation to the cir... [more]
Showing records 448 to 472 of 641. [First] Page: 1 15 16 17 18 19 20 21 22 23 Last
[Show All Keywords]