Fluid Dynamics Code ANSYS FLUENT Research Articles

Heat transfer characteristics for multi-silicon ingots irradiation in a typical research reactor

A computational fluid dynamics (CFD) study is conducted for silicon ingot irradiation facility in a typical material testing reactor (MTR). The ingots are placed inside the irradiation device in staggered and in-line bundles. The configurations are varied according to the variations of longitudinal and transverse pitches Sl and St, respectively. For in-line bundles, Sl and St are changed in the range of 1.1, 1.2, 1.3, 1.4, and 1.5 of the ingot diameter. For staggered bundles, Sl is changed in the range of 1.1, 1.2, 1.3, 1.4, and 1.5 of the ingot diameter while St is changed in the range of 0.95, 1.0, 1.05, 1.1, and 1.15 of the ingot diameter. The silicon ingot volumetric heat generation Qv is allowed to change around its nominal value in the range of 0.25, 0.5, 0.75, 1.0, and 1.25 W/g. The effects of rotation of ingots during irradiation at velocities of 15, 30, and 60 rpm are investigated. The computational fluid dynamics code ANSYS FLUENT is employed to carry out the calculations. The temperature profile inside the silicon ingot during irradiation is of significant importance for uniform doping. Therefore, the impact of heat generation and bundle pitches on the temperature profile through the ingot is calculated and reported for all cases of this study. The results show that the maximum ingot temperature does not exceed the limits for each bundle at maximum heat generation. Two correlations for average Nusselt number for both aligned and staggered configurations are generated to describe heat transfer rates during natural convection regime. The rotation of ingots during irradiation showed considerable enhancement of heat transfer rates.

NACA0009 ve NACA4415 Kanat Profillerinin Sayısal ve İstatistiksel Aerodinamik Performans Analizi

In this numerical and statistical study, lift and drag coefficient performances of NACA-0009 and NACA-4415 airfoils were evaluated in accordance with various attack angle at constant velocity of wind. Lift and drag coefficients of airfoils was numerically determined by computational fluid dynamics code ANSYS FLUENT. Analysis design of numerical calculations was implemented using L16 orthogonal array based on Taguchi method. Angles of attack and airfoil types were considered as control factors. The optimum level and effect of each control factor on responses was statistically implemented using analyses of Signal-to-Noise ratio and variance. As a result of this study, maximum lift and minimum drag coefficient were achieved by using NACA4415 airfoil compared to NACA0009 airfoil. The increase of the angle of attack leads to the increase on the lift and drag coefficients for both airfoils.

A Novel Optimized Solar Trough Profile for Better Solar Energy Collection, Storage, and Levelized Cost

The performance of concentrated solar power plants with parabolic trough collectors (PTCs) can be enhanced by introducing troughs with an optimized mirror profile. Therefore, the present work introduces a method for achieving optimum trough profiles (TPs). Advanced numerical investigation is performed using the computational fluid dynamics code Ansys Fluent. Multi‐objective multidimensional optimization is implemented to obtain two optimum profiles; namely OTP1 and OTP2. Results show that these profiles improve the overall efficiency by 8.3% and 7.1% under different operating conditions and incidence angles compared to a PTC with the same aperture area. Moreover, the surface areas of OTP1 and OTP2 are less than that of the PTC by 12.3% and 10.7%, respectively. This reduces the mirror cost, required amount of wash water, and wash time. Analysis of the levelized cost of energy (LCOE) without thermal energy storage (TES) shows that the implementation of OTP1 and OTP2 reduces the LCOE compared to that of the PTC by 2.6% and 2.3%, respectively. Moreover, a significant reduction in the LCOE is achieved by applying TES under typical Egyptian operating conditions. Implementing 6 h of TES reduces the LCOE compared to the case without TES by 34.5%, 35.3%, and 35.1% for the PTC, OTP1, and OTP2, respectively.

Analysis of viscous wave generation at low Ursell number in an optimal numerical wave tank using inlet velocity method

The present study analyzes the viscous wave generation at a low Ursell number in an optimal numerical wave tank. Commercial computational fluid dynamics code ANSYS FLUENT software is used in a two-dimensional numerical wave tank in this model. The finite volume method is a discretization technique to solve the Reynolds-average Navier–Stokes equations. The inlet velocity method is used to generate the desired waves. The standard k–ε turbulent model is used for the verification. Viscous models were tested at a constant water depth ( d) under 12 cases to complete the analysis. Surface elevation, wave velocities, velocity contour, and streamlined motions are important studies in this problem. Simulating result shows that the wave velocities ( u, w) at the free surface ( z = 0) increase with the wave steepness ( H/L) at a particular time period ( T) and gradually decrease from the free surface ( z = 0) toward the bottom of the water ( z = − d). Many practical systems, such as wave energy converters, offshore marine constructions, and other ocean engineering challenges, may benefit significantly from this research's realistic wave creation. This analysis of different periods gives the knowledge of flow behavior which provides the previous test of the scale model.

Thermal hydraulic characteristics of silicon irradiation in a typical MTR reactor

Abstract In this work, a three-dimensional study is conducted for silicon ingot irradiation facility in a typical MTR reactor. The silicon ingot heat generation is allowed to change around its nominal value in the range of 0.25, 0.5, 0.75, 1.0, and 1.25 W/g. The dimensionless clearance ratio ζ between the ingot and the outer casing is changed for values of 0.01, 0.05, 0.1, 0.15, and 0.2. The computational fluid dynamics code ANSYS FLUENT is employed to carry out these calculations. The temperature profile inside the silicon ingot during irradiation is of significant importance for uniform doping. Therefore, the impact of Rayleigh number and dimensionless clearance ratio ζ on the radial and axial temperature profiles through the ingot is reported. A best estimate correlation for the silicon irradiation facility global Nusselt number in terms of Rayleigh and dimensionless clearance ratio is presented. The dimensionless clearance ratio ζ value of 0.05 gives the best thermal hydraulic performance. Comparison with the available experimental correlations in the literature shows good agreement.

Influence of the Curvature Correction on Turbulence Models for the Prediction of the Aerodynamic Coefficients of the S809 Airfoil

Using the appropriate procedure, Computational Fluid Dynamics allows predicting many things in several fields, and especially in the field of renewable energies, which has become a promising research axis. The present study aims at highlighting the influence of the curvature correction on turbulence models for the prediction of the aerodynamic coefficients of the S809 airfoil using the Computational Fluid Dynamics code ANSYS Fluent 17.2. Three turbulence models are used: Spalart-Allmaras, Shear Stress Transport k-ω and Transition SST. Experimental results of the 1.8 m × 1.25 m low-turbulence wind tunnel at the Delft University of Technology are used in this work for comparison with the numerical results for a Reynolds number of 106. The results show that the use of the curvature correction improves the prediction of the aerodynamic coefficients for all the turbulence models used. A comparison of the three models is also made using curvature correction since it gave better results. The Transition SST model is the one that gives the best results for the lift coefficient, followed by the Shear Stress Transport kω model, and finally the Spalart-Allmaras model. For the drag coefficient, Transition SST model is the best, followed by the Spalart-Allmaras model, and finally the Shear Stress Transport kω model.

An Efficient Scheme for Coupling OpenMC and FLUENT with Adaptive Load Balancing

This paper develops a multi-physics interface code MC-FLUENT to couple the Monte Carlo code OpenMC with the commercial computational fluid dynamics code ANSYS FLUENT. The implementations and parallel performances of block Gauss–Seidel-type and block Jacobi-type Picard iterative algorithms have been investigated. In addition, this paper introduces two adaptive load-balancing algorithms into the neutronics and thermal-hydraulics coupled simulation to reduce the time cost of computation. Considering that the different scalability of OpenMC and FLUENT limits the performance of block Gauss–Seidel algorithm, an adaptive load-balancing algorithm that can increase the number of nodes dynamically is proposed to improve its efficiency. Moreover, with the natural parallelism of block Jacobi algorithm, another adaptive load-balancing algorithm is proposed to improve its performance. A 3 x 3 PWR fuel pin model and a 1000 MWt ABR metallic benchmark core were used to compare the performances of the two algorithms and verify the effectiveness of the two adaptive load-balancing algorithms. The results show that the adaptive load-balancing algorithms proposed in this paper can greatly improve the computing efficiency of block Jacobi algorithm and improve the performance of block Gauss–Seidel algorithm when the number of nodes is large. In addition, the adaptive load-balancing algorithms are especially effective when a case demands different computational power of OpenMC and FLUENT.

Modeling of Transonic Transitional Three-Dimensional Flows for Aerodynamic Applications

The paper describes a technology designed for computing three-dimensional transonic laminar–turbulent flows at various aerodynamic configurations with the use of the general-purpose computational fluid dynamics code ANSYS Fluent and an integrated special module of computing the laminar–turbulent transition position created on the basis of the autonomous software package LOTRAN 3, developed previously by the authors. Within the framework of this technology, computations with a prolate spheroid and engine nacelle are performed for different Mach numbers ( Reynolds numbers ), and angles of attack ( to ). New results are obtained on the position of the laminar–turbulent transition in boundary layers in transonic flow regimes, and the problem of the dominating transition mechanism is considered. The results obtained in the present study are demonstrated to be in good agreement with experimental data on the position of the laminar–turbulent transition available in the literature.

Effects of Vertical Glottal Duct Length on Intraglottal Pressures in the Convergent Glottis

In a previous study, the vertical glottal duct length was examined for its influence on intraglottal pressures and other aerodynamic parameters in the uniform glottis [J Voice 32, 8–22 (2018)]. This study extends that work for convergent glottal angles, the shape of the glottis during the glottal opening phase of vocal fold vibration. The computational fluid dynamics code ANSYS Fluent 6.3 was used to obtain the pressure distributions and other aerodynamic parameters for laminar, incompressible, two-dimensional flow in a static vocal fold model. Four typical vertical glottal duct lengths (0.108, 0.308, 0.608, 0.908 cm) were selected for three minimal diameters (0.01, 0.04, 0.16 cm), three transglottal pressures (500, 1000, 1500 Pa), and three convergent glottal angles (−5°, −10°, −20°). The results suggest that a longer vertical glottal duct length increases the intraglottal pressures, decreases the glottal entrance loss coefficient, increases the transglottal pressure coefficient, causes a lower gradient of both the intraglottal flow velocity and the wall shear stress along the glottal wall—especially for low flows and small glottal minimal diameters—and has little effect on the exit pressure coefficient and volume flow. The vertical glottal duct length in the convergent glottis has important effects on phonation and should be well specified when building computational and physical models of the vocal folds.

Numerical simulation of lignocellulosic biomass gasification in concentric tube entrained flow gasifier through computational fluid dynamics

Thermochemical conversion of biomass is an encouraging way for the production of syngas. In the present research, four different biomass materials were used for gasification which includes rice husk, cotton stalks, sugarcane bagasse, and sawdust. These biomass sources were selected because they are common Pakistani feedstocks. Gasification of selected biomasses was performed using concentric tube entrained flow gasifier. Three-dimensional computational fluid dynamics model was used to investigate the impacts of kinetic rate and diffusion rate on the gasification performance. The Euler–Lagrange method was used for the development of entrained flow biomass gasifier using commercial computational fluid dynamics code ANSYS FLUENT®14. Discrete phase model was used to predict the movement of particles, whereas the gas phase was treated as the continuous phase with a standard k–ε turbulent model to predict the behavior of gas phase flow. Finite rate/Eddy dissipation model was applied for the calculation of homogenous and heterogeneous reaction rates. Oxygen was used as a gasifying agent. Cotton stalks and sugarcane bagasse produced higher mole fractions of hydrogen (H2) and carbon monoxide (CO) than sawdust and rice husk. Regarding carbon conversion efficiency, cold gas efficiency, and higher heating value cotton stalks and sugarcane bagasse produced better syngas quality as compared to sawdust and rice husk. The oxygen/fuel (O/F) ratio is a key operating parameter in the field of gasification and combustion. The O/F ratio above 0.42 favored combustion reactions and increased mole fraction of water vapor (H2O) and carbon dioxide (CO2) in syngas composition, whereas gasification reactions dominated below 0.42 O/F ratio, resulting increased mole fraction of H2 and CO in syngas composition.

Influence of Perforated Fin on Flow Characteristics and Thermal Performance in Spiral Finned-Tube Heat Exchanger

The present study conducts the numerical investigation of flow characteristics and thermal performance of spiral finned-tube heat exchangers. The effects of location of perforations (90°, 120°, and 150°) on heat transfer and pressure drop are analyzed for the air-side. The commercial computational fluid dynamics code ANSYS Fluent (V.17.0) is used for simulations with the RNG k-ε model based on the Reynolds-averaged Navier–Stokes equations. The velocity field, Colburn j-factor, and friction factor are analyzed to evaluate the heat transfer and pressure drop characteristics. Because of the flow through the perforations, the boundary layers on the fin surfaces are interrupted. This results in increased flow disturbances close to the fin, and the heat transfer performance increases compared to the reference case. The pressure drop, which is one of the disadvantages of spiral finned tubes comparing to plate or circular fins, decreases with perforations on the fin. Overall, the cases with perforated fin exhibit greater performance of area goodness factor considering the relationship between the heat transfer and the pressure drop.

The Influence of Shaping Air Pressure of Pneumatic Spray Gun

The shaping air pressure is a very important parameter in the application of pneumatic spray gun, and studying its influence on spray flow field and film thickness distribution has practical values. In this paper, Euler-Lagrangian method is adopted to describe the two-phase spray flow of pneumatic painting process, and the air flow fields, spray patterns and dynamic film thickness distributions were obtained with the help of the computational fluid dynamics code—ANSYS Fluent. Results show that with the increase of the shaping air pressure, the air phase flow field spreads in the plane perpendicular to the shaping air hole plane, the spray pattern becomes narrower and flatter, and the width of the dynamic film increases with the reduced maximum value of the film thickness. But the film thickness distribution seems to change little with the shaping air pressure decreasing from 0.6bar to 0.9bar.

Optimal Design of Novel Drill Bit to Control Dust in Down-the-Hole Hammer Reverse Circulation Drilling

In pneumatic down-the-hole hammer drilling with reverse circulation, dusty air often escapes from the borehole due to the adverse effects of reverse circulation, which not only pollutes the surrounding environment, but also affects workers’ health. In order to address this issue, a new type of drill bit, designed with a swirling generator, has been developed. The computational fluid dynamics code ANSYS Fluent was used to simulate the swirling flow phenomena inside the drill bit, and the simulation results indicate that a stronger swirling flow field can be formed in the drill bit’s center passage. This swirling flow has a high entrainment effect, so that negative pressure is generated in the nearest area, which is helpful for improving the reverse circulation effects. Furthermore, a series of experiments were carried out to test the actual performance of the drill bit, and the experimental results exhibit reasonable agreement with the simulation data. The maximum error between the simulated and experimental results is only 9.05%. The mass flow rate of the sucked air increases with an increase in air supply, regardless of whether flushing nozzles are designed for the drill bit. Moreover, the amount of air sucked into the swirling drill bit is greater than that sucked into the annular drill bit under the same conditions; therefore, the swirling drill bit exhibits superior performance.

CFD Modeling of Legionella's Atmospheric Dispersion in the Explosive Outbreak in Murcia, Spain

ABSTRACTCooling towers, among other equipment, could have an important atmospheric impact, becoming a source of pollutants or biological agents. The most important, due to its frequency and importance of the outbreaks, is Legionella. Since its discovery in 1976 in Philadelphia, PA, several outbreaks have been reported causing tens of deaths. The most important one took place in the city of Murcia, Spain, in 2001, with more than 600 cases. In the present work, a validated numerical model using the computational fluid dynamics code ANSYS Fluent is employed to simulate the dispersion of the drift from the cooling tower causative of the outbreak in the urban environment of Murcia in the days of highest emissions. The results of the model are compared with the results of the epidemiological investigation carried out by the Epidemiology Service (Consejería de Sanidad, Murcia, Spain). The main objective of this model is to predict a cooling tower influence area, and what will help to reduce environmental and personal impact in case of an infection of its water or to improve the resources used to find the focus of infection after an outbreak has taken place. The model was previously validated using data from an experimental cooling tower installation.

CFD Modeling of Syngas Combustion and Emissions for Marine Gas Turbine Applications

Abstract Strong restrictions on emissions from marine power plants will probably be adopted in the near future. One of the measures which can be considered to reduce exhaust gases emissions is the use of alternative fuels. Synthesis gases are considered competitive renewable gaseous fuels which can be used in marine gas turbines for both propulsion and electric power generation on ships. The paper analyses combustion and emission characteristics of syngas fuel in marine gas turbines. Syngas fuel is burned in a gas turbine can combustor. The gas turbine can combustor with swirl is designed to burn the fuel efficiently and reduce the emissions. The analysis is performed numerically using the computational fluid dynamics code ANSYS FLUENT. Different operating conditions are considered within the numerical runs. The obtained numerical results are compared with experimental data and satisfactory agreement is obtained. The effect of syngas fuel composition and the swirl number values on temperature contours, and exhaust gas species concentrations are presented in this paper. The results show an increase of peak flame temperature for the syngas compared to natural gas fuel combustion at the same operating conditions while the NO emission becomes lower. In addition, lower CO2 emissions and increased CO emissions at the combustor exit are obtained for the syngas, compared to the natural gas fuel.

Numerical simulation of transient temperature profiles for canned apple puree in semi-rigid aluminum based packaging during pasteurization.

Pasteurization of canned apple puree was simulated for a 3-D geometry in a semi-rigid aluminum based container which was heated from all sides at 378K. The computational fluid dynamics code Ansys Fluent 14.0 was used and the governing equations for energy, momentum, and continuity were computed using a finite volume method. The food model was assumed to have temperature-dependent properties. To validate the simulation, the apple puree was pasteurized in a water cascading retort. The effect of the mesh structures was studied for the temperature profiles during thermal processing. The experimental temperature in the slowest heating zone in the container was compared with the temperature predicted by the model and the difference was not significant. The study also investigated the impact of head space (water-vapor) on heat transfer.