Fluid Dynamics Software ANSYS Fluent Research Articles

Numerical study on the energy-harvesting performance of a semi-activated coupled-pitching hydrofoil in shear flows

A two-dimensional numerical model of a semi-activated coupled-pitching hydrofoil was established using the computational fluid dynamics software ANSYS Fluent. The kinematic response, hydrodynamic characteristics, and energy-harvesting performance of the hydrofoil in shear flow were investigated. The coupled-pitching hydrofoil achieved a stable limited-cycle passive-pitching motion and efficient energy harvesting in shear flows under various shear rates, pitching amplitudes, and reduced frequencies. The flow structures, pressure distributions, and hydrodynamic torque were analyzed to reveal the mechanism of the stable passive-pitching motion of the coupled-pitching hydrofoil in shear flow. The stable passive-pitching motion was dominated by the hydrodynamic torque, which was equivalent during the upward and downward strokes. Shear flow has a certain degree of influence on energy-harvesting efficiency. The energy-harvesting efficiency decreased with increasing shear rate. When the activated-pitching amplitude is small, the effect of shear rate on energy-harvesting performance was limited. The effect of shear rate was enhanced as the activated-pitching amplitude increased. The average relative difference in the energy-harvesting efficiency in the uniform and shear flows was 15 %, when the activated-pitching amplitude was 70° and the shear rate was 1.0. The peak value of the efficiency can reach 19.8 % when the shear rate was 1.0. The coupled-pitching hydrofoil is adaptable to shear flows. The results of this study provide valuable information for the application of coupled-pitching hydrofoils under real tidal flow conditions.

Investigation of Taylor bubble dynamics in annular conduits with counter-current flow

This study numerically investigates counter-current slug flow by considering the motion of a Taylor bubble in annular conduits with downward-flowing liquids using the Volume-of-Fluid method implemented in the commercial computational fluid dynamics software ANSYS Fluent (Release 19.2). The translational velocity of a counter-current ascending or co-current descending Taylor bubble in vertical concentric annuli and the corresponding distribution parameter (C0) are analyzed. The latter is correlated in terms of Eötvös number (Eo) and inverse viscosity number (Nf) within the range of Eo between 40 and 400 and Nf between 40 and 320. The proposed correlation provides an accurate fit to the numerical data with an average error of 2.64%, and is successfully compared with published numerical findings. In general, the smooth and stable shape of the bubble is disrupted as the counter-current flow velocity (Frl) increases above a critical value, leading to the formation of surface waves and the displacement of the bubble tip away from the annular gap center and towards the outer pipe. C0 increases with Eo and Nf, plateauing at high values of Eo. The effects of annulus inclination (θ) and eccentricity (ε) on bubble rise velocity are examined within the common range of θ and ε encountered during the drilling of oil, gas, or geothermal wells, i.e. 0° ≤ θ ≤ 60° and 0 ≤ ε ≤ 0.7, and their impact on the C0. The increasing Frl and θ lead to a streamlined bubble with pointed nose and thus a reduction in the wrap angle (θwrap), ultimately leading to reduced drag compared to the vertical annulus case and a decrease in C0. As the ε increases, which is accompanied by an increase in the degree of bubble eccentricity, the corresponding C0 decreases. For a constant Eo = 100 and Nf = 160 with inclination angle of θ = 40°and eccentricity of ε = 0.5, the C0 < 1 is observed.

Analysis of the aerodynamic characteristics of an ejection seat system using computational fluid dynamics

In the present work, an investigation of the aerodynamic characteristics of an ejection seat occupant is carried out using the commercially available computational fluid dynamics software ANSYS Fluent. 3D Reynolds-averaged Navier–Stokes equations are solved to obtain the aerodynamic coefficients of the ejection seat system. For this analysis, an unstructured grid is generated for the ejection seat occupant using ANSYS meshing. Validation is carried out and the performance of three different turbulence models is analyzed at Mach 0.6. Based on the most suitable turbulence model, further analysis of the aerodynamic coefficients of the ejection seat occupant is calculated at Mach numbers of 0.35, 0.45, 0.55, 0.65, and 0.75. For all values of Mach, the angle of attack is varied from −15° to 15° in 5° increments and the yaw angle is varied from 0° to 60° in 10° increments. Based on the results, it is observed that the magnitude of the axial force decreases with increasing angle of attack and yaw angle. Similarly, the normal force coefficient and pitching moment coefficient decrease with increasing angle of attack. Finally, the side force coefficient, yawing moment, and rolling moment coefficients increase with increasing yaw angle.

Design of a high counting efficiency sensor for 1.0 cubic feet per minute laser particle counter.

Based on the theory of Mie scattering, an optical sensor for a 1.0 cubic feet per minute laser particle counter is developed in this paper. First, an illumination optical path relying on aspherical lens and cylindrical lens for laser shaping was designed, and a narrow optical spot with the illumination in the vertical direction of the photosensitive area approximately distributed as a flat top was obtained. Second, the scattering light path was designed by using the theory of Mie scattering and geometric optics method. Then, the structure of the sampling air path was designed with reference to the principle of Laval nozzle, and the particle flow trajectory was verified by simulation using the fluid dynamics software Ansys Fluent. Finally, the performance of the optical sensor was measured with polystyrene latex (PSL) particles, and the results showed that the counting efficiency of the 0.3μm particle size channel met the requirement of 50% ± 20% and the 0.5μm particle size channel met the requirement of 100% ± 10%, which complied with the ISO 21501-4 standard.

A J-Type Air-Cooled Battery Thermal Management System Design and Optimization Based on the Electro-Thermal Coupled Model

Air-cooled battery thermal management system (BTMS) is a widely adopted temperature control strategy for lithium-ion batteries. However, a battery pack with this type of BTMS typically suffers from high temperatures and large temperature differences (∆T). To address this issue, this study conducted an electro-thermal coupled model to optimize the flow channel structure for reducing the maximum temperature (Tmax) and ∆T in a battery pack for a “J-type” air-cooled BTMS. The parameters required to predict battery heat generation were obtained from a single battery testing experiment. The flow and heat transfer model in a battery pack that had 24 18650 batteries was established by the Computational Fluid Dynamics software ANSYS Fluent 2020R2. The simulation results were validated by the measurement from the battery testing experiment. Using the proposed model, parameter analysis has been implemented. The flow channel structure was optimized in terms of the duct size, battery spacing, and battery arrangement for the air-cooled BTMS. The original BTMS was optimized to reduce Tmax and ∆T by 1.57 K and 0.80 K, respectively. This study may provide a valuable reference for designing air-cooled BTMS.

Efficient Cooling System for Lithium-Ion Battery Cells by Using Different Concentrations of Nanoparticles of SiO2-Water: A Numerical Investigation

The performance, safety, and cycle life of lithium-ion batteries (LiBs) are all known to be greatly influenced by temperature. In this work, an innovative cooling system is employed with a Reynolds number range of 15,000 to 30,000 to minimize the temperature of LiB cells. The continuity, momentum, and energy equations are solved using the Finite Volume Method (FVM). The computational fluid dynamics software ANSYS Fluent is applied to calculate the flow and temperature fields and to analyze the thermal management system for 52 LiB cells. The arrangement of batteries leads to symmetrical flow and temperature distribution occurring in the upper and lower halves of the battery pack. The impacts of SiO2 distributed in a base fluid (water) are investigated. The results show that SiO2 nanofluid with the highest volume fractions of 5% has the lowest average temperature values at all investigated Reynolds numbers. The innovative cooling system highlights the enhancement of the cooling process by increasing the SiO2 concentrations, leading to the recommendation of the concentration of 5 vol% due to better thermal diffusion resulting from the enhanced effective thermal conductivity. The flow turbulence is increased by increasing the Reynolds number, which significantly enhances the heat transfer process. It is shown that increasing the Re from 15,000 to 22,500 and 30,000 causes increases in the Nu value of roughly 32% and 65%, respectively.

CFD Simulation on Aerodynamic Performance of Hyperloop Vehicle

Aerodynamic drag is one of the most opposing factors for ground vehicle. This becomes even more difficult while travelling through a tunnel. The Evacuated- Tube Trains (ETTs) or Hyperloop’s are a new concept of ground transportation presently being developed by many different companies. The main purpose of an Hyperloop can be displayed as a cheaper medium of ground transport, which could allow its consumers to propagate to different places at a cheaper and faster rate compared to the present day locomotives and road transport. Passengers can travel at over 700 mph in floating capsules that swoop along within gigantic low-pressure tubes that are either below or above surface. This study analyses the Hyperloop designs using Computational Fluid Dynamics software ANSYS FLUENT. The effects of operating speed, Capsule shape and internal tube pressure have been studied in this paper. The flow inside the tube is considered as turbulent and incompressible. The software simulation results show the significant effects of inside pressure and operating speed on the aerodynamic drag of the capsule. Study with different shapes for the Capsule’s front and rear end suggest the most optimum shape for least aerodynamic drag.

Flow Structure Characteristics of the Simplified Compact Car Exposed to Crosswind Effects using CFD

Aerodynamic characteristics of a car are important in reducing car accidents caused by wind loading and in lowering fuel economy, continuing to be a major topic of interest. The restrictions of wind tunnel tests and the rising trend of numerical methods have been complied with by past researchers to investigate vehicle aerodynamics computationally. This research aims to analyze comprehensively the effect of crosswinds on a moving vehicle in terms of aerodynamic loadings and flow structures using commercial fluid dynamic software ANSYS FLUENT. This paper will focus on the CFD-based simplified compact car body developed in CATIA V5 by neglecting the external parts such as side mirrors and underbody.

Numerical study on the thermodynamic performance of a packed bed cryogenic energy storage system

• Developed a 3-D porous media model for cryogenic energy storage in a packed bed. • Studied the influence of key factors on cold charging performance of the packed bed. • Operating conditions of cryogenic gas charged packed bed were analyzed. Cold energy storage devices improve the round-trip efficiency of cryogenic energy storage systems, where a solid packed bed for cold energy storage (PBCES) is widely utilized. In this study, a three-dimensional transient porous media packed bed model was developed using computational fluid dynamics software ANSYS Fluent 2020 to study the thermodynamic characteristics of a solid PBCES system with cryogenic nitrogen as the working medium during the cold charging process. The effects of the superficial mass flow rate ( G in ), inlet temperature of nitrogen, packing materials, porosity on the packed bed temperature distribution, pressure drop, cold storage efficiency ( η s ), and cold exergy efficiency ( η Ex ) were investigated carefully. The results showed that the axial temperature distribution is a typical thermocline. The system performance is predominantly affected by the criterion of the complete charging (the minimum temperature difference between Face-2 and Face-1, Δ T F2-F1,min ) and the G in . The thermocline thickness decreased with a decrease in the G in . The η s and η Ex increased significantly with an increase in the Δ T F2-F1,min . The maximum η s and η Ex were 77.69% and 75.21% at the G in was 0.1 kg/(m 2 ·s) when the Δ T F2-F1,min was 100 K. The change in porosity had a limited influence on the cryogenic storage performance but considerably influenced the pressure drop; Basalt was recommended as the optimal packing material in the present study. The superficial mass flow rate of working medium and the complete charging indicator (Δ T F2-F1,min ) should be carefully determined to achieve high performance in a practical CES system. The developed simulation model would be promising and useful for the design and optimization of a practical packed bed for CES systems.

Multiphase simulation and parametric study of direct vapor generation for a solar organic Rankine Cycle

Parabolic trough collectors coupled with Organic Rankine Cycles are an attractive option for decentralized power generation. This work is dedicated to the parametric study of a parabolic trough collector system filled with benzene under solar irradiation for use in an Organic Rankine Cycle; the Computational Fluid Dynamics software ANSYS FLUENT was used in the study. Different inlet temperatures (465, 475 and 485 K), mass fluxes (168, 336 and 504 kg/m2s), and solar-concentrated heat fluxes (15.1, 18.5 and 22.2 kW/m2) are used in the simulations. The numerical model is validated with experimental data to a good concordance (maximum measured error for outlet equilibrium vapor quality and temperature is about 6 % and 0.01 %, respectively). The results indicate that (1) the inlet temperature does not have an effect in the fluid boiling behavior, (2) increasing the mass flow rate decreases the fluid evaporation rate, (3) the fluid evaporation rate is directly affected by the solar heat flux and (4) the mass flux affects the point where evaporation begins occurring (tube lengths of 10, 15 and 25 m for mass fluxes of 168, 336 and 504 kg/m2s, to 15.1 kW/m2, respectively.) Results also show that an excessive heat flux can result in large thermal gradients inside the collector (hence, overheating), and an excessive mass flow will delay the net vapor generation point.

A CFD Energetic study of the influence of the panel orientation in Open Joint Ventilated Façades

The arrangement of the panels in Open Joint Ventilated Façades (OJVF) is a potential factor in improving the energy efficiency of this building system. The distribution of joints in the façade influences the behaviour of the air flow in the channel which in turn could affect the overall heat exchanges with the envelope and thus the internal conditions of the building. Tiling panels can be installed on ventilated façades with different arrangement patterns according to the layout of the joints: lined up, staggered, stepped, diagonal or random, although manufacturers recommend a façade layout with in-line gaps to avoid costly façade maintenance. Thus, landscape and portrait layout with continuous joints are the most frequent arrangement in ventilated façades. This research assesses the benefit of the installation of OJVF panels in both layouts in order to reduce the cooling loads. Two real OJVFs with different panel arrangements, landscape and portrait, are analysed. Also, they are compared with a conventional façade with a sealed air cavity. All solutions are modelled and simulated using the commercial computational fluid dynamics software ANSYS FLUENT to evaluate the fluid-dynamic and thermal behaviour of the façades in summer and winter conditions. The energy performance of these solutions is evaluated, analysing different parameters such as panel’s temperature, mean air velocity inside the cavity, fluid pathlines through the open joints and thermal flux in the air cavity and to the room. The airflow inside the cavity is mainly driven by thermal buoyancy in all façades but differs from bi-dimensional convective loops in conventional façades to three-dimensional complex and asymmetrical airflows in OJVFs. The results obtained show that both OJVF configurations perform much better than the conventional sealed façade, reducing the heat transfer into the room by 30% in the summer period. In any case, the landscape OJVF façade reduces the transfer in the same period to a minimum value of 7.3 W/m2, which is 3% less than the flux transferred through the vertical one. This small difference in the energy performance of OJVFs makes the choice of panel orientation more based on other criteria such as aesthetics.

Numerical Investigation of a Drag Reduction Device Applied to the Ahmed Body

In this paper, a new technique of drag reduction around a simplified car body called the Ahmed body is introduced. A conduit has been perforated in this body. The purpose of this conduit is bringing part of airflow from the body’s front to be injected in its rear end where the recirculation occurs. In this study, a numerical model of a turbulent flow around a two–dimensional then three–dimensional body has been developed. Numerical simulations have been performed using the computational fluid dynamics software ANSYS Fluent. For the 2D case, series of numerical simulations have been performed. In these simulations, the conduit position relative to the body’s lower slant edge has been modified. For the position with minimum drag, the effect of narrowing the conduit exit has been tested. Finally, the effect of narrowing the conduit exit has been studied. For the 3D case, the effect of changing dimensions of a rectangular conduit and its position from the body’s lower slant edge have been studied. For the position with lower drag, the effect of narrowing the conduit exit has been studied. The 2D and 3D results show that in some conduit configurations, drag could be reduced.

Nature inspired design modification of fluidic diode for wave energy harvesting device

Abstract A fluidic diode (FD) coupled with the unidirectional turbine (UT) can improve its flow rectification operating in a bi-directional airflow. However, the shape of the FD is not standardized like other fluidic components, and they are usually problem-specific. The performance of the FD is given by diodicity, which is the ratio of pressure drop for the reverse to forward direction. This article aims to improve the performance of the FD proposed for wave energy application by modifying its shape, which is inspired by the bud of the lotus flower. The modified model is numerically studied by solving three-dimensional steady-state Reynolds Averaged Navier Stokes equations using the commercial computational fluid dynamics software ANSYS FLUENT 16.2. The proposed modification had a lesser pressure drop in both directions compared to the base model. The detailed flow physics and performance analysis of the modified FD are presented.

Investigation of the direct-flow burners and nozzles arrangement at the direct-flow-vortex coal combustion in a furnace with solid slag removal

The paper presents results of the furnace aerodynamics investigation using direct-flow burners and air nozzles (DFBAN) with solid slag removal (SSR). The studies were performed using the computational fluid dynamics software ANSYS Fluent. The paper includes recommendations for the development of effective solid fuel combustion schemes with DFBAN, methods for researching and optimization of the combustion aerodynamics with the use of DFBAN, optimization criteria, initial data for the study. The scheme for burning Kuznetsk lean coal with the use of DFBAN and SSR was developed. Several series of calculations were performed for the developed scheme. In these calculations, the dependencies of the indicators of efficiency, furnace ecological safety and reliability on the nozzles and burners positions, which are located in the first zone of the scheme, were found. The first stage of the optimization of the developed scheme burning solid fuel with the SSR was made.

Investigation of helical strut attached vena cava filter hemodynamic performanc

Hemodynamic performance of the Celect Platinum vena cava filter and the revised forms of it with helical flow inducer strut were studied with computational fluid dynamic software Ansys Fluent 18. The central velocity and shear stress increased but overall flow disturbance has been observed minimal level. Central velocity increases to 9.72% with Celect filter, by the single helical flow inducer strut the rate reaches to 14.69%, and with doubled form it reaches to 19.73%. The filter surface shear rate increases to 8.29% with the single helical flow inducer strut and increases 13.31% with doubled attachment. Increased velocity and shear stress on the filter may eliminate short term thrombus build-up problems by breaking the big size particulates with the high shearing forces. The new struts may also contribute to the ability of the filter to capture smaller clots, as well as to dissolve them from being bigger. Shear stress in the vein wall increases approximately 6.63% with the filter placement. It raises to 8.06% and 9.45% with single and double helical flow inducer strut attachment. Increased vein wall shear may reduce the recirculation and clotting in the vein wall and it may prevent the accumulation of clots. The increased shear stress on the filter may cause the migration problem, design improvements can minimize this risk. Helical flow inducer strut attachment can cause efficacy increase, and the flow are normalized.

Analysis of Blockage Accident of Lead-Based Fast Reactor Single-Box Fuel Assembly Based on CFD

The corrosion products produced during the operation of the lead-based reactor may be deposited in the reactor, resulting in the occurrence of flow plugging accident. Based on the computational fluid dynamics software Ansys Fluent, the effects of different blockage area, thickness, type and position on the deterioration of heat transfer and the properties of flow field in current plugging accident are analyzed. The results show that the increasing of blockage area will increase the reflux area, which makes the temperature fall more slowly and the heat transfer worsen obviously; the increasing of the blockage thickness will lead to the increasing of the maximum temperature of coolant and cladding, which can easily lead to cladding damage; the coolant in the porous medium blockage passes at a lower flow rate, which alleviates the influence of blockage and does less harm than the solid blockage. The local warming caused by the blockage located in the middle of the active area is more obvious and more harmful than that caused by the blockage in the entrance and exit of the active area.

Large eddy simulation of Taylor-Couette turbulent flow under transverse magnetic field

By the large eddy simulation method, the turbulent Taylor-Couette flow of conducting fluid under a homogenous transverse magnetic field is investigated through using the computational fluid dynamic software ANSYS Fluent 17.0. The flow is confined between two infinitely long cylinders, thus a periodic boundary condition is imposed in the axial direction. The inner cylinder rotates while the outer one is at rest, and their radius ratio is 1/2. Two Reynolds numbers of 3000 and 5000 are considered in the simulations, and the Hartmann number is varied from 0 to 50. In the present study, we assume a lower magnetic Reynolds number &lt;inline-formula&gt;&lt;tex-math id="Z-20210904222045"&gt;\begin{document}$Re_{\rm m} \ll 1$\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="18-20210389_Z-20210904222045.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="18-20210389_Z-20210904222045.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;, i.e., the influence of the induced magnetic field on the flow is negligible in comparison with the imposed magnetic field. The evolution of Taylor vortices, velocity profile of mean flow, and turbulent kinetic energy distribution under the transverse magnetic field are analyzed and compared with the results of the axial magnetic field counterpart. It shows that the imposed magnetic field has a significant damping effect on the Taylor-Couette flow. The twisted Taylor vortices break into small-scale vortex structures under the transverse magnetic field and they arrange themselves along the magnetic field. The fluctuations which are perpendicular to the magnetic field are suppressed effectively, while the one which is parallel to the magnetic field is nearly uninfluenced, resulting in quasi-two-dimensional elongated structure in the flow field. As anticipated, in a sufficiently strong magnetic field, the turbulent Taylor-Couette flow may eventually decay to a Couette laminar flow. In the outer cylinder and the area perpendicular to the direction of the magnetic field, the suppression effect is even stronger than those in any other places and fewer vortices are observed in the simulations. The turbulent kinetic energy is transferred firstly from large eddies to intermediate eddies, then to small eddies, and finally dissipated due to the viscous and Joule effect. As the Reynolds number increases, the suppression effect of the magnetic field weakens, and the flow behaves divergently in different areas of the apparatus. Compared with the axial magnetic field, the transverse magnetic field has a weak suppression effect on the flow field, and the profiles of related variables are obviously anisotropic.

Solid fuel combustion processes modelling in the furnace in terms of the boiler K-50-14-250

The paper presents the numerical simulation results of furnace of the boiler K-50-14-250 for three operation modes with computational fluid dynamics software ANSYS Fluent. The boiler is located at industrial heating boiler house in Tashtagol town. The selection of models for the boiler furnace operation simulation is given. A study of simulation results independence on the mesh size was conducted, based on which a computational mesh was selected for further research. The numerical simulation results of three modes furnace operation were compared with the results of the field tests (flue gas temperature at the furnace outlet, combustible losses, heat absorption of the furnace heating surfaces, the nitrogen oxides concentration in the exhaust gases at excess air ratio α = 1.4). Besides, a slagging process numerical simulation of the furnace waterwalls performed. The numerical simulation results of the near nominal load furnace operation are compared with the results of physical isothermal modelling by matching the streamlines from the burners and air nozzles of the boiler. The paper summary is the verification of numerical models of the solid fuel combustion in the furnace, in terms of the boiler K-50-14-250.

Experimental and computational investigation of engine characteristics in a compression ignition engine using mahua oil

Many research works have been carried out worldwide for finding a suitable substitute for diesel which is predominantly used for Heavy Vehicles, and creating a validated numerical model which will be useful for effective performance predictions. A lot of experimental work has been carried out using Pure Mahua oil as an alternative to diesel. But an extensive numerical analysis for the same has not been carried out so far. In this research, combustion and emission characteristics of pure Mahua oil as an alternative to diesel running at 40%, 80% and 100% load has been carried out experimentally and theoretically using Computational Fluid Dynamics software ANSYS Fluent ICE. An extensive CFD simulation analysis was carried out using the dimensions of the Compression Ignition engine used for the experiment by considering a cylindrical domain in which a 60 degrees Sector of combustion chamber taken for analysis. Transient Computational Fluid Dynamics (CFD) analysis has been carried out by using injection profile and other engine data as input for the combustion simulation. The simulated combustion parameters that were considered for interpretation includes the Pressure-Crank Angle (P-ϴ), Temperature Crank Angle (T-ϴ) and Apparent heat release rate. The experimental and simulation results presented in this article justifies Mahua Oil as a potential alternative for Diesel. From this research work we conclude that though the combustion and performance characteristics of Mahua Oil is less compared to that of Diesel, the lesser Nox emissions and cost of the fuel makes it as an attractive alternative for diesel.

Parametric analysis and design optimisation of PCM thermal energy storage system for space cooling of buildings

The paper presents a parametric analysis and design optimisation of an active PCM thermal energy storage system for space cooling of nearly zero-energy buildings. The design for a new space cooling system proposes a TES system composed of stand-alone PCM storage units incorporated into the building interior under the ceiling slab. Active control of the thermal energy storage is realized by night cooling of a phase change material by means of cold water flowing within a capillary pipe system. The objective of the study is to examine the effect of the system’s main parameters such as PCM layer thickness, number of parallel pipes, diameter of pipes, night cooling duration, cooling water inlet temperature and velocity under Baltic summer weather conditions. Parametric analysis is performed by using computational fluid dynamics software Ansys Fluent. Optimisation of the main parameters is carried out to determine the best combination of their values ensuring the system is able to absorb the daily thermal loads within the room and operates with minimum energy consumption for the night cooling of PCM.