Records with Keyword: Computational Fluid Dynamics
Showing records 1 to 25 of 472. [First] Page: 1 2 3 4 5 Last
Thermo-Fluid Dynamic and Kinetic Modeling of Hydrothermal Carbonization of Olive Pomace in a Batch Reactor
Barbara Mendecka, Giovanni Di Ilio, Lidia Lombardi
March 29, 2023 (v1)
Keywords: biomass upgrading, Computational Fluid Dynamics, hydrothermal carbonization, olive pomace
Hydrothermal carbonization (HTC) represents one of the emerging and most promising technologies for upgrading biomass. Among the residual biomass waste, olive pomace and olive mill wastewater may be seen as valuable energy sources, especially for the Mediterranean countries, given the key role of the olive oil industry in those regions. This paper deals with the thermo-fluid dynamic performance of the HTC process of olive pomace. Computational Fluid Dynamics (CFD) modeling is employed in this study to numerically simulate such a process in batch reactor with the aim of understanding the complex fluid dynamics, heat transfer and reaction kinetics phenomena occurring under hydrothermal conditions. A parametric analysis is performed to evaluate the temperature fields inside the reactor and the output mass yields as a function of the power input required by the process. Velocity flow fields and the spatial distribution of the mixture during the process are also investigated to understand t... [more]
Transient CFD Simulation on Dynamic Characteristics of Annular Seal under Large Eccentricities and Disturbances
Kai Zhang, Xinkuo Jiang, Shiyang Li, Bin Huang, Shuai Yang, Peng Wu, Dazhuan Wu
March 29, 2023 (v1)
Keywords: annular seal, Computational Fluid Dynamics, dynamic coefficients, fluid forces, nonlinear dynamic model, static eccentricity
Annular seals of turbomachinery usually suffer from various degrees of eccentricities and disturbances due to the rotor−stator misalignment and radial loads, while the discussion of annular seal under both large static eccentricities and dynamic disturbances is relatively limited. In this paper, the applicability of linear assumption and reliability of nonlinear dynamic model for eccentric annular seals under large eccentricities and disturbances is discussed based on the investigation of seals with various rotor motions through computational fluid dynamics (CFD). After the validation of transient CFD methods by comparison with experimental and bulk theory results, the dynamic behaviors of annular seal are analyzed by adopting both direct transient simulations and the nonlinear Muszynska model. The results show that the nonlinear dynamic model based on rotor circular whirls around seal center can predict the fluid excitations of different types of rotor motions well under small static... [more]
The Influence of Radial and Axial Gaps on Volumetric Efficiency of External Gear Pumps
Paulina Szwemin, Wieslaw Fiebig
March 28, 2023 (v1)
Keywords: Computational Fluid Dynamics, gear pump, leakage flow, pump modelling
The design of gear pumps and motors is focused on more efficient units which are possible to achieve using advanced numerical simulation techniques. The flow that appears inside the gear pump is very complex, despite the simple design of the pump itself. The identification of fluid flow phenomena in areas inside the pump, considering the entire range of operating parameters, is a major challenge. This paper presents the results of simulation studies of leakages in axial and radial gaps in an external gear pump carried out for different gap shapes and sizes, as well as various operating parameters. To investigate the processes that affect pump efficiency and visualize the fluid flow phenomena during the pump’s operation, a CFD model was built. It allows for a detailed analysis of the impact of the gears’ eccentricity on leakages and pressure build-up on the circumference. Performed simulations made it possible to indicate the relationship between leakages resulting from the axial and ra... [more]
The Influence of Front Wing Pressure Distribution on Wheel Wake Aerodynamics of a F1 Car
Daniel Martins, João Correia, André Silva
March 28, 2023 (v1)
Keywords: Computational Fluid Dynamics, Formula One, front wing, racing car, transient, wheel
The present study focuses on investigating the aerodynamic interaction between a three-element wing and wheel in ground effect, following the Formula One regulation change set for 2022, among which is the simplification of the front wing. This was accomplished by conducting a three-dimensional computational fluid dynamics analysis, using a Detached-Eddy Simulation approach, on a simplified one-quarter model of a Formula One racing car. The main goal was to examine how changing the front wing pressure distribution, by changing the incidence of the second flap, affected the wheel wake. The flow investigation indicated that the wheel wake is influenced by the flap configuration, which is mainly due to the fact that different flap configurations produce different upwash flow fields, leading to a variation of the separation point on top of the tire. As the separation point moves rearwards, the downwash generated in the central region (for a vertical plane) of the wheel wake increases increm... [more]
Ultra-Lean Premixed Turbulent Combustion: Challenges of RANS Modelling
Lorenzo Sforza, Suliman Abdelwahid, Tommaso Lucchini, Angelo Onorati
March 28, 2023 (v1)
Keywords: CFM, Computational Fluid Dynamics, FAM, flamelet, premixed turbulent combustion, RANS, ultra-lean combustion
The main challenge of improving spark ignition (SI) engines to achieve ever increasing thermal efficiencies and near-zero pollutant emissions today concerns developing turbulent combustion under homogeneous ultra-lean premixed mixtures (HULP). This continuous shift of the lean operation limit entails questions on the applicability limits of the combustion models used to date for SI engine design and optimization. In this work, an assessment of flamelet-based models, widely used in RANS SI engines simulations of premixed turbulent combustion, is carried out using an open-source 3D-CFD platform to clarify the applicability limits on HULP mixtures. Two different consolidated approaches are selected: the Coherent Flame Model (CFM) and the Flame Area Model (FAM). Both methodologies are embedded by the authors into the same numerical structure and compared against measurements over a simplified and controlled flame configuration, which is representative of engine-like conditions. The experim... [more]
Numerical Investigation of the Adsorption Process of Zeolite/Water in a Thermochemical Reactor for Seasonal Heat Storage
Elham Abohamzeh, Georg Frey
March 28, 2023 (v1)
Keywords: adsorption process, Computational Fluid Dynamics, energy storage density, thermochemical heat storage, zeolite
Zeolite 13X molecular sieve with high sorption capacity and significant sorption rate has been considered a promising candidate for seasonal heat storage. In this study, a code is developed to simulate the adsorption process between zeolite and water in all ranges of partial pressures, temperatures, and sorbate loadings. The results from the proposed code were compared with experiments and good agreement was observed. After validation, the developed model was used to study the effective parameters involved in the adsorption process of binder-free Zeolite 13X. A parametric study considering various temperatures and water content in the inflow air was conducted and the influence of different factors on the outlet temperature and adsorption enthalpy has been studied. This parametric study gives a good insight into the measures which can be taken for achieving the desired released energy or having the outlet temperature in the preferred range. The simulations have been conducted in a varie... [more]
Computational Fluid Dynamic Analysis of the Pharyngeal Airway after Bimaxillary Orthognathic Surgery in Patients with Mandibular Prognathism
Puneet Wadhwa, Hyon-Seok Jang, Se-Hyun Park, Hyoung-Ho Kim, Eui-Seok Lee
March 28, 2023 (v1)
Keywords: adjusted pressure coefficient, Computational Fluid Dynamics, orthognathic surgery, pharyngeal airway, pressure drop, upper airway volume
This study aimed to analyze pharyngeal airflow characteristics and their relationship with the skeletal movement of the maxilla and mandible after bimaxillary orthognathic surgery in patients with skeletal class III (mandibular prognathism) malocclusion. Cone-beam computed tomography (CBCT) was conducted before surgery (T0), immediately after surgery (T1), and at least six months after surgery (T2). Digital imaging and communications in medicine files were transferred to InVivo (Anatomage) software to measure the skeletal changes after surgery. The changes in the maxillary and mandibular position, tongue position, and hyoid bone position were analyzed. Patient-specific models were reconstructed using 3D-Doctor software. The models after converting to the stereolithography (STL) file for Ansys integrated computer engineering and manufacturing code for computational fluid dynamics (ICEM CFD), commercial software were used for calculating the geometry, pressure drop and adjusted pressure... [more]
Numerical Analyses of Heterogeneous CLC Reaction and Transport Processes in Large Oxygen Carrier Particles
Guanping Huo, Xueyan Guo
March 28, 2023 (v1)
Keywords: chemical looping combustion, Computational Fluid Dynamics, heterogeneous, intraparticle diffusion, oxygen carrier, packed bed
Heterogeneous chemical looping combustion (CLC) reactions and conjugate transports in large oxygen carrier particles were numerically investigated with computational fluid dynamics (CFD) approaches, in which a simplified noncatalytic reaction model was implemented for reducing intraparticle modelling computation. Volumic gas-solid reactions were treated as surface reactions based on the equivalent internal surface in the particle model. In large porous particles such as fixed bed CLC reactors, the heterogeneous reactions are often limited by intraparticle diffusion. Comprehensive analyses were conducted on transports across the particle surface and their influences on reactions inside the single particles. A threshold Reynolds number of external convections was found for the enhancement of intraparticle reactions. The heterogeneous reactions, intraparticle diffusions and interstitial transports in a fixed bed CLC reactor randomly packed with 597 spheres were thoroughly analysed with th... [more]
Full-Field Comparison of MRV and CFD of Gas Flow through Regular Catalytic Monolithic Structures
Mojtaba Mirdrikvand, Mehrdad Sadeghi, Georg R. Pesch, Wolfgang Dreher, Jorg Thöming
March 28, 2023 (v1)
Keywords: Computational Fluid Dynamics, dispersion, flow, gas, maldistribution, NMR, velocity
Understanding the influence of gas flow maldistribution in honeycombs can be beneficial for the process design in various technical applications. Although recent studies have investigated the effect of maldistribution by comparing the results of numerical simulations with experimental measurements, an exhaustive 3D full-field comparison is still lacking. Such full-field comparisons are required to identify and eliminate possible limitations of numerical and experimental tools. For that purpose, spatially resolved flow patterns were simulated by computational fluid dynamics (CFD) and measured experimentally by non-invasive NMR velocimetry (MRV). While the latter might suffer from a misinterpretation of artefacts, the reliability of CFD is linked to correctly chosen boundary conditions. Here, a full-field numerical and experimental analysis of the gas flow within catalytic honeycombs is presented. The velocity field of thermally polarized methane gas was measured in a regular 3D-printed... [more]
CFD Modelling of a Hydrogen/Air PEM Fuel Cell with a Serpentine Gas Distributor
Alessandro d’Adamo, Matteo Riccardi, Massimo Borghi, Stefano Fontanesi
March 28, 2023 (v1)
Keywords: Computational Fluid Dynamics, electrochemistry, Fuel Cells
Hydrogen-fueled fuel cells are considered one of the key strategies to tackle the achievement of fully-sustainable mobility. The transportation sector is paying significant attention to the development and industrialization of proton exchange membrane fuel cells (PEMFC) to be introduced alongside batteries, reaching the goal of complete de-carbonization. In this paper a multi-phase, multi-component, and non-isothermal 3D-CFD model is presented to simulate the fluid, heat, and charge transport processes developing inside a hydrogen/air PEMFC with a serpentine-type gas distributor. Model results are compared against experimental data in terms of polarization and power density curves, including an improved formulation of exchange current density at the cathode catalyst layer, improving the simulation results’ accuracy in the activation-dominated region. Then, 3D-CFD fields of reactants’ delivery to the active electrochemical surface, reaction rates, temperature distributions, and liquid w... [more]
Temperature-Dependent Viscosity Model for Silicone Oil and Its Application in Viscous Dampers
Márk Venczel, Gabriella Bognár, Árpád Veress
March 28, 2023 (v1)
Keywords: Carreau–Yasuda viscosity model, Computational Fluid Dynamics, non-Newtonian fluid, rheology, silicone oil, viscous torsional vibration damper
Silicone fluids belong to the group of pseudoplastic non-Newtonian fluids with complex rheological characteristics. They are considered in basic and applied researches and in a wide range of industrial applications due to their favorable physical and thermal properties. One of their specific field of applications in the automotive industry is the working fluid of viscous torsional vibration dampers. For numerical studies in the design and development phase of this damping product, it is essential to have thorough rheological knowledge and mathematical description about the silicone oil viscosity. In the present work, adopted rheological measurement results conducted on polydimethylsiloxane manufactured by Wacker Chemie with initial viscosity of 1000 Pas (AK 1 000 000 STAB silicone oil) are processed. As a result of the parameter identification by nonlinear regression, the temperature-dependent parameter curves of the Carreau−Yasuda non-Newtonian viscosity model are generated. By implem... [more]
Model-Based Solution for Upgrading Nitrogen Removal for a Full-Scale Municipal Wastewater Treatment Plant with CASS Process
Mengmeng Liu, Meixue Chen, Rong Qi, Dawei Yu, Min Yang, Jiaxi Zheng, Yuansong Wei, Haizhou Du
March 28, 2023 (v1)
Keywords: activated sludge model No.1 (ASM1), CASS WWTP, Computational Fluid Dynamics, full-scale, sensitivity analysis
Aiming at providing cost-effective approach for upgrading the existing municipal wastewater treatment plants in the cold region of China to meet more stringent discharge standards of nitrogen removal, a full-scale sewage treatment plant with the CASS process was selected through focusing on biological process, key equipment and hydrodynamics in bioreactors by the activated sludge model 1 (ASM1) and computational fluid dynamics (CFD) model. Influent COD fractions and the key characteristic parameters (YH and bH) of the activated sludge were determined through the respirometry at temperatures of 10 °C and 20 °C, respectively. The layout of submerged agitator installation in the bioreactor of the CASS process was optimized through CFD simulation. The calculation of the average relative deviation (less than 20%) between simulated data and the operation data, demonstrated that the ASM1 model could be reasonably used in the wastewater treatment plant simulation. The upgrade solution based on... [more]
Effect of an Inducer-Type Guide Vane on Hydraulic Losses at the Inter-Stage Flow Passage of a Multistage Centrifugal Pump
Mohamed Murshid Shamsuddeen, Sang-Bum Ma, Sung Kim, Ji-Hoon Yoon, Kwang-Hee Lee, Changjun Jung, Jin-Hyuk Kim
March 28, 2023 (v1)
Keywords: Computational Fluid Dynamics, double-suction impeller, inducer-type guide vane, multistage centrifugal pump, twin-volute
A multistage centrifugal pump was developed for high head and high flow rate applications. A double-suction impeller and a twin-volute were installed at the first stage followed by an impeller, diffuser and return vanes for the next four stages. An initial design feasibility study was conducted using three-dimensional computational fluid dynamics tools to study the performance and the hydraulic losses associated with the design. Substantial losses in head and efficiency were observed at the interface between the first stage volute and the second stage impeller. An inducer-type guide vane (ITGV) was installed at this location to mitigate the losses by reducing the circumferential velocity of the fluid exiting the volute. The ITGV regulated the pre-swirl of the fluid entering the second stage impeller. The pump with and without ITGV is compared at the design flow rate. The pump with ITGV increased the stage head by 63.28% and stage efficiency by 47.17% at the second stage. As a result, t... [more]
Numerical Study on the Aerodynamic Characteristics of the NACA 0018 Airfoil at Low Reynolds Number for Darrieus Wind Turbines Using the Transition SST Model
Krzysztof Rogowski, Grzegorz Królak, Galih Bangga
March 28, 2023 (v1)
Keywords: airfoil transition modelling, Computational Fluid Dynamics, separation bubble, transition SST, URANS, VAWT
A symmetrical NACA 0018 airfoil is often used in such applications as small-to-medium scale vertical-axis wind turbines and aerial vehicles. A review of the literature indicates a large gap in experimental studies of this airfoil at low and moderate Reynolds numbers in the previous century. This gap has limited the potential development of classical turbulence models, which in this range of Reynolds numbers predict the lift coefficients with insufficiently accurate results in comparison to contemporary experimental studies. Therefore, this paper validates the aerodynamic performance of the NACA 0018 airfoil and the characteristics of the laminar separation bubble formed on its suction side using the standard uncalibrated four-equation Transition SST turbulence model and the unsteady Reynolds-averaged Navier-Stokes (URANS) equations. A numerical study was conducted for the chord Reynolds number of 160,000, angles of attack between 0 and 11 degrees, as well as for the free-stream turbule... [more]
Mechanism of the Absent Air Column in Three Products Hydrocyclone Screen (TPHS): Experiment and Simulation
Chuanzhen Wang, Anghong Yu, Zaisheng Zhu, Haizeng Liu, Md. Shakhaoath Khan
March 28, 2023 (v1)
Keywords: air column, Computational Fluid Dynamics, high definition camera experiment, reynolds stress model, three products hydrocyclone screen
Three products hyrdrocyclone screen (TPHS) has been proposed for particle separation based on size. In TPHS, a cylindrical screen was embedded in a conventional hydrocyclone (CH) to combine the centrifugal classification and screening to particle separation based on size. The industrial application of TPHS indicates its better device performance than CH. Although, the earlier studies reveal some common understanding for TPHS, the information of the absent air column remains unknown. Hence, the combination of physical experiment and numerical simulation was considered involving a 75 mm TPHS for this knowledge gap. First, both the computational fluid dynamics (CFD) simulation with Reynolds stress mode and the physical experiment with a high-definition camera illustrate the development process details of a flow field in TPHS. That is, the water was imported along the tangential inlet into TPHS; then under the effects of the feed chamber wall and gravity, the liquid phase spiraled downward... [more]
Parametric Study on a Performance of a Small Counter-Rotating Wind Turbine
Michał Pacholczyk, Dariusz Karkosiński
March 28, 2023 (v1)
Keywords: actuator line model, Computational Fluid Dynamics, counter-rotating wind turbine, wind energy
A small Counter-Rotating Wind Turbine (CRWT) has been proposed and its performance has been investigated numerically. Results of a parametric study have been presented in this paper. As parameters, the axial distance between rotors and a tip speed ratio of each rotor have been selected. Performance parameters have been compared with reference to a Single Rotor Wind Turbine (SRWT). Simulations were carried out with Computational Fluids Dynamics (CFD) solver and a Large Eddy Scale approach to model turbulences. An Actuator Line Model has been chosen to represent rotors in the computational domain. Summing up the results of simulation tests, it can be stated that when constructing a CRWT turbine, rotors should be placed at a distance of at least 0.5 D (where D is rotor outer diameter) or more. One can then expect a noticeable power increase compared to a single rotor turbine. Placing the second rotor closer than 0.5 D guarantees a significant increase in power, but in such configurations,... [more]
Analysis of the Fire Propagation in a Sublevel Coal Mine
Florencio Fernánez-Alaiz, Ana Maria Castañón, Fernando Gómez-Fernández, Antonio Bernardo-Sánchez, Marc Bascompta
March 28, 2023 (v1)
Keywords: coal mine, computational fluid dynamic, Computational Fluid Dynamics, FDS, fire dynamics simulator, gob fire, underground mine
A fire has been analyzed in a real underground coal mine, using a sublevel method, during an entire year. The study was focused on the collapsed area, reproducing a real mixture formed by coal, waste, and air gap. The analysis was done by means of an experimental analysis, a computational fuid dynamic model (CFD), and simulations using a mine ventilation software. Three scenarios were determined and studied regarding their influence on the evolution of the fire: (a) development of the fire without taking any action, (b) sealing off the affected areas, and (c) sealing and reducing the ventilation in the affected area and surrounding drifts. The study revealed the behavior of the fire in a real mine and the effectiveness of the main fire-fighting measures over time, verifying that none of the measures taken could eliminate the fire-induced in the collapsed area.
Effects of Injector Spray Angle on Performance of an Opposed-Piston Free-Piston Engine
Qinglin Zhang, Zhaoping Xu, Shuangshuang Liu, Liang Liu
March 28, 2023 (v1)
Keywords: combustion, Computational Fluid Dynamics, free-piston engine, performance, spray angle
A free-piston engine is a novel internal combustion engine which has the advantages of a variable compression ratio and multi-fuel adaptability. This paper focuses on numerical simulation for combustion process and spray angle optimization of an opposed-piston free-piston engine. The working principle and spray-guided central combustor structure of the engine are discussed. A three-dimensional computational fluid dynamic model with moving mesh is presented based on the tested piston motion of the prototype. Calculation conditions, spray models, and combustion models were set-up according to the same prototype. The effects of spray angle on fuel evaporation rate, mixture distribution, heat release rate, in-cylinder pressure, in-cylinder temperature, and emissions were simulated and analyzed in detail. The research results indicate that the performance of the engine was very sensitive to the spray angle. The combustion efficiency and the indicated thermal efficiencies of 97.5% and 39.7%... [more]
Fast Design Procedure for Turboexpanders in Pressure Energy Recovery Applications
Gaetano Morgese, Francesco Fornarelli, Paolo Oresta, Tommaso Capurso, Michele Stefanizzi, Sergio M. Camporeale, Marco Torresi
March 27, 2023 (v1)
Keywords: Computational Fluid Dynamics, energy recovery, modelling techniques, throttling valves, turboexpander
Sustainable development can no longer neglect the growth of those technologies that look at the recovery of any energy waste in industrial processes. For example, in almost every industrial plant it happens that pressure energy is wasted in throttling devices for pressure and flow control needs. Clearly, the recovery of this wasted energy can be considered as an opportunity to reach not only a higher plant energy efficiency, but also the reduction of the plant Operating Expenditures (OpEx). In recent years, it is getting common to replace throttling valves with turbine-based systems (tuboexpander) thus getting both the pressure control and the energy recovery, for instance, producing electricity. However, the wide range of possible operating conditions, technical requirements and design constrains determine highly customized constructions of these turboexpanders. Furthermore, manufacturers are interested in tools enabling them to rapidly get the design of their products. For these reas... [more]
Unsteady Natural Convection in a Cylindrical Containment Vessel (CIGMA) With External Wall Cooling: Numerical CFD Simulation
Ari Hamdani, Satoshi Abe, Masahiro Ishigaki, Yasuteru Sibamoto, Taisuke Yonomoto
March 27, 2023 (v1)
Keywords: CIGMA, Computational Fluid Dynamics, conjugate heat transfer, containment vessel, natural convection, thermal hydraulics
In the case of a severe accident, natural convection plays an important role in the atmosphere mixing of nuclear reactor containments. In this case, the natural convection might not in the steady-state condition. Hence, instead of steady-state simulation, the transient simulation should be performed to understand natural convection in the accident scenario within a nuclear reactor containment. The present study, therefore, was aimed at the transient 3-D numerical simulations of natural convection of air around a cylindrical containment with unsteady thermal boundary conditions (BCs) at the vessel wall. For this purpose, the experiment series was done in the CIGMA facility at Japan Atomic Energy Agency (JAEA). The upper vessel or both the upper vessel and the middle jacket was cooled by subcooled water, while the lower vessel was thermally insulated. A 3-D model was simulated with OpenFOAM®, applying the unsteady Reynolds-averaged Navier−Stokes equations (URANS) model. Different turbule... [more]
Effect of Air-Ducted Blade Design on Horizontal Axis Wind Turbine Performance
Cemil Yigit
March 27, 2023 (v1)
Keywords: blade design, Computational Fluid Dynamics, horizontal axis wind turbine, power coefficient, response surface optimization
Wind turbines without pitch control are more preferable from economical point of view but aerodynamic stall affects them more and after a critical wind speed local boundary layer separation occurs. Consequently, their power production is relatively low. In this study, air ducts added on the blade and using the airflow from them the kinetic energy of the low-momentum fluid behind the surface was increased and delay of separation of the boundary layer from the surface was examined The Response Surface Optimization method was utilized in order to get the best possible design under the constraints and targets arranged for the parameters termed the diameter, slope, number and angle of attack of the air ducts. By using computational fluid dynamics analysis, optimum parameter values were obtained and air-ducted and air-duct free blade designs were compared. An improvement in power coefficient between 3.4−4.4% depending on wind speed was achieved with the new design. Due to increase in viscous... [more]
Modeling of Selected Lighting Parameters of LED Panel
Krzysztof Baran, Antoni Różowicz, Henryk Wachta, Sebastian Różowicz
March 27, 2023 (v1)
Keywords: Computational Fluid Dynamics, junction temperature, LED panel, lighting parameters, thermal modeling
Semiconductor light sources are currently the fastest growing and most energy efficient group of light sources used in lighting technology. Their lighting parameters, such as luminous flux, correlated color temperature and color rendering index depend on the value of the forward current, as well as the temperature of the junction. LED source manufacturers usually specify, in data sheets, the effect of junction temperature and forward current on the luminous flux for individual light sources. The difficulty, however, is the correct determination of temperature and then lighting parameters, by simulation methods for multi-source lighting systems. Determining the junction temperature which affects lighting parameters is particulary important in the case of LED panels and luminaires, where thermally coupled LED sources shaping the output lighting parameters are in close proximity to each other. Additionally, other factors influencing the temperature distribution of sources, such as the des... [more]
Heat Transfer through Wire Cloth Micro Heat Exchanger
Christian Walter, Sebastian Martens, Christian Zander, Carsten Mehring, Ulrich Nieken
March 27, 2023 (v1)
Keywords: Computational Fluid Dynamics, dimensioning, heat exchanger, heat transfer, micro tubes, Modelling, wire structure
The main objective of this study is to calculate and determine design parameters for a novel wire cloth micro heat exchanger. Wire cloth micro heat exchangers offer a range of promising applications in the chemical industry, plastics technology, the recycling industry and energy technology. We derived correlations to calculate the heat transfer rate, pressure drop and temperature distributions through the woven structure in order to design wire cloth heat exchangers for different applications. Computational Fluid Dynamics (CFD) simulations have been carried out to determine correlations for the dimensionless Euler and Nusselt numbers. Based on these correlations, we have developed a simplified model in which the correlations can be used to calculate temperature distributions and heat exchanger performance. This allows a wire cloth micro heat exchanger to be virtually designed for different applications.
Bio-Inspired Rotor Design Characterization of a Horizontal Axis Wind Turbine
J. Gaitan-Aroca, Fabio Sierra, Jose Ulises Castellanos Contreras
March 27, 2023 (v1)
Keywords: bio-inspired wind turbines, Computational Fluid Dynamics, wind turbine, wind turbines performance
In this paper, the performance of a biomimetic wind rotor design inspired by Petrea Volubilis seed is presented. Experimentation for this rotor is configured as a horizontal axis wind turbine (HAWT) and numerical analysis is done in order to obtain performance curves with the open-source computational fluid dynamics (CFD) software OpenFoam®. Numerical analysis and experimental results are compared for power Coefficient (Cp) and thrust coefficient (CT). The biomimetic rotor analysis is also compared with experimental results exposed by Castañeda et al. (2011), who were the first to develop those experimentations with this new rotor design. Computational fluid dynamics simulations were performed using an incompressible large Edyy simulation (LES) turbulence models with a localized sub-grid scale (SGS) dynamic one-equation eddy-viscosity. A dynamic mesh based on an arbitrary mesh interface (AMI) was used to simulate rotation and to evaluate flow around rotor blades in order to accurately... [more]
Time-Splitting Coupling of WaveDyn with OpenFOAM by Fidelity Limit Identified from a WEC in Extreme Waves
Pierre-Henri Musiedlak, Edward J. Ransley, Martyn Hann, Benjamin Child, Deborah M. Greaves
March 27, 2023 (v1)
Keywords: Computational Fluid Dynamics, cummins equation, extreme waves and responses, hybrid code, numerical limit, wave steepness
Survivability assessment is the complexity compromising Wave energy development. The present study develops a hybrid model aiming to reduce computational power while maintaining accuracy for survivability assessment of a Point-Absorber (PA) Wave Energy Converter (WEC) in extreme Wave Structure Interaction (WSI). This method couples the fast inviscid linear potential flow time-domain model WaveDyn (1.2, DNV-GL, Bristol, UK) with the fully nonlinear viscous Navier−Stokes Computational Fluid Dynamics (CFD) code OpenFOAM (4.2,, London, UK). The coupling technique enables the simulation to change between codes, depending on an indicator relating to wave steepness identified as a function of the confidence in the linear model solution. During the CFD part of the simulation, the OpenFOAM solution is returned to WaveDyn via an additional load term, thus including viscous effects. Developments ensure a satisfactory initialisation of CFD simulation to be achieved from a ‘hot-start’... [more]
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