Air Flow and Heat Transfer in a Temperature-Controlled Open Top Enclosure

2012 ◽  
Author(s):  
Charlotte Barbier ◽  
Paul J. Hanson ◽  
Donald E. Todd ◽  
Damen Belcher ◽  
Eriks W. Jekabson ◽  
...  
Keyword(s):  
Wind Speed ◽  
Operating Cost ◽  
Cfd Simulations ◽  
Heating Systems ◽  
Elevated Atmospheric Co2 ◽  
Heating Efficiency ◽  
Oak Ridge ◽  
Flow And Heat Transfer ◽  
Ansys Cfx ◽  
Computational Fluid Dynamics Cfd

A large 12-meter-diameter open top enclosure (OTE) equipped with two unique belowground and above ground heating systems was built and intensively tested in Oak Ridge, TN, USA. The OTE is a prototype for use within an environmental change experiment, in which replica units will be built in Minnesota to assess the response of northern peatland ecosystems to increases in temperature and elevated atmospheric CO2. For several months, temperatures, energy, wind speed and relative humidity were monitored throughout the enclosure space to assess the enclosure performance and efficiency. In parallel, Computational Fluid Dynamics (CFD) simulations were performed with ANSYS-CFX to investigate the impacts of external wind, buoyancy, and OTE design on the temperatures achieved within the enclosure. The addition of a frustum that partially reduced the top opening was also investigated experimentally and numerically. The OTE is capable of achieving a temperature differential of at least +6°C for air using a combination of 8 electrical heaters. Differential temperatures were sustained for several months. The experimental data and the numerical results showed that the addition of a frustum dramatically decreases the operating cost of the OTE and leads to better control over the differential air temperature in the enclosure. Buoyancy forces and winds heavily impacted enclosure performance. It was also found that the heating efficiency of the OTE depends mainly on the wind speed, and that there exists a critical wind speed at which the heating efficiency is the highest.

CFD and Experimental Analysis of Centrifugal Fans With Forward Curved Blades Used in Electric Motors

2019 ◽  
Author(s):  
S. S. Borges
Keyword(s):  
Cfd Simulation ◽  
Experimental Tests ◽  
Performance Comparison ◽  
Centrifugal Fan ◽  
Electric Motors ◽  
Cfd Simulations ◽  
Interface Models ◽  
Ansys Cfx ◽  
Centrifugal Fans ◽  
Computational Fluid Dynamics Cfd

Abstract This work presents an analysis of the aerodynamic performance of a centrifugal fan with forward curved blades (Sirocco) applied to electric motors. In this analysis were carried out computational fluid dynamics (CFD) simulations and experimental tests for comparison of results. The focus of this analysis is the performance comparison among three different models of general connection interface that are required for the connection between the grids of the rotating and stationary domains of CFD simulation, considering the method adopted by the Ansys CFX, software used as computational tool. Thereby, Frozen Rotor, Stage, and Transient Rotor-Stator were the interface models evaluated. For comparison reference, the experimental data were used to evaluate the performance of each interface models for overall operating range of the fan.

Numerical and experimental analysis of rotating wheel in contact with the ground

2018 ◽  
Vol 28 (5) ◽  
pp. 1203-1217 ◽  
Author(s):  
Michal Kulak ◽  
Maciej Karczewski ◽  
Pawel Lesniewicz ◽  
Krzysztof Olasek ◽  
Bas Hoogterp ◽  
...  
Keyword(s):  
Aerodynamic Drag ◽  
Cfd Simulations ◽  
Content Type ◽  
Car Body ◽  
Aerodynamic Properties ◽  
University Of Technology ◽  
Ansys Cfx ◽  
Key Factor ◽  
Computational Fluid Dynamics Cfd ◽  
Practical Implications

Purpose This paper aims to provide the results of investigations concerning an influence of the tyre with longitudinal grooves on the car body aerodynamics. It is considered as an important aspect affecting the vehicle aerodynamic drag. Design/methodology/approach To investigate a contribution of grooved tyres to the overall vehicle drag, three wind tunnel experimental campaigns were performed (two by Peugeot Société Anonyme Peugeot Citroen, one at the Lodz University of Technology). In parallel, computational fluid dynamics (CFD) simulations were conducted with the ANSYS CFX software to enable formulation of wider conclusions. Findings The research shows that optimised tread patterns can be derived on a single tyre via a CFD study in combination with a controlled experiment to deliver designs actively lowering the overall vehicle aerodynamic drag. Practical implications A reduction in the aerodynamic drag is one of ways to decrease vehicle fuel consumption. Alternatively, it can be translated into an increase in the maximum travel velocity and the maximum distance driven (key factor in electric vehicles), as well as in a reduction of CO2 emissions. Finally, it can improve the vehicle driving and steering stability. Originality/value The tyre tread pattern analysis on isolated wheels provides an opportunity to cut costs of R&D and could be a step towards isolating aerodynamic properties of tyres, irrespective of the car body on which they are applied.

Ablation and Aero-thermodynamic Studies on Thermal Protection Systems of Sharp-Nosed Re-entry Vehicles

2006 ◽  
Vol 129 (7) ◽  
pp. 912-916 ◽  
Author(s):  
S. Rameche Candane ◽  
C. Balaji ◽  
S. P. Venkateshan
Keyword(s):  
Thermodynamic Analysis ◽  
Thermal Protection ◽  
Ablation Rate ◽  
Heat Fluxes ◽  
Zirconium Boride ◽  
Cfd Simulations ◽  
Flow And Heat Transfer ◽  
Commercial Code ◽  
Computational Fluid Dynamics Cfd ◽  
Viscous Compressible Flow

A quasi-one-dimensional ablation analysis for a sharp-nosed, reusable, re-entry vehicle that could possibly be used in an unmanned space program, has been carried out by using an in-house code. The code is based on the boundary immobilization technique and the solution has been obtained using the tri-diagonal matrix algorithm (TDMA). The heat fluxes on the spherical nose cap that are used to determine the ablation rate of a thermal coating applied over the surface of the vehicle are obtained by performing a steady state aero-thermodynamic analysis. The aero-thermodynamic analysis for the viscous, compressible flow under consideration is carried out by using FLUENT 6.2. The computational fluid dynamics (CFD) simulations are performed at three locations on the trajectory that the vehicle follows, on re-entry. These simulations yield the temperature and heat flux distributions along the surface of the vehicle and the latter are given as input to the ablation code. The shell material of the vehicle is assumed to be zirconium boride (ZrB2). The code is validated with benchmark cases and the flow and heat transfer characteristics are also discussed. In brief, the present work presents a methodology for coupling an ablation code with CFD simulations from a commercial code, to study the effect of change of the nose region on the ablation process.

Maximization of Solar Gains of an Air Collector by Simulations

2013 ◽  
Vol 284-287 ◽  
pp. 483-487 ◽  
Author(s):  
Ondrej Sikula ◽  
Vit Merka ◽  
Jiri Hirs ◽  
Josef Plášek
Keyword(s):  
Heat Transfer ◽  
Solar Energy ◽  
Solar Collector ◽  
Cfd Simulations ◽  
Ansys Fluent ◽  
Operation Conditions ◽  
Flow And Heat Transfer ◽  
Solar Air Collector ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

The paper deals with numerical simulations of the impact of design, shading, positioning and orientation of a solar air collector an efficiency of exploitation of solar energy. The solar collector is used to preheat of an air, which then is supplied into the building. There are various requirements for solar air collectors. We are focused on maximization of solar energy gain by optimizing geometry, orientation and positioning of a solar air collector. To achieve the desired objective was a combination of two methods used. The firs one is Computational Fluid Dynamics (CFD) simulations of flow and heat transfer by convection, conduction and radiation in software ANSYS Fluent. The second one is the numerical simulation of the annual operations of the collector in the software BSim. The result of this work is an optimal design and operation conditions of the air collector.

scholarly journals Numerical simulations and Arctic observations of surface wind effects on Multi-Angle Snowflake Camera measurements

2020 ◽  
Author(s):  
Kyle E. Fitch ◽  
Chaoxun Hang ◽  
Ahmad Talaei ◽  
Timothy J. Garrett
Keyword(s):  
Wind Speed ◽  
Surface Wind ◽  
Free Fall ◽  
Threshold Value ◽  
Cfd Simulations ◽  
Upward Velocity ◽  
Atmospheric Radiation Measurement ◽  
Computational Fluid Dynamics Cfd ◽  
The Mean ◽  
Fall Speed

Abstract. Ground-based measurements of frozen precipitation are heavily influenced by interactions of surface winds with gauge-shield geometry. The Multi-Angle Snowflake Camera (MASC), which photographs hydrometeors in free-fall from three different angles while simultaneously measuring their fall speed, has been used in the field at multiple mid-latitude and polar locations both with and without wind shielding. Here we show results of computational fluid dynamics (CFD) simulations of the airflow and corresponding particle trajectories around the unshielded MASC and compare these results to Arctic field observations with and without a Belfort double Alter shield. Simulations in the absence of a wind shield show a separation of flow at the upstream side of the instrument, with an upward velocity component just above the aperture, which decreases the mean particle fall speed by 55 % (74 %) for a wind speed of 5 m s−1 (10 m s−1). MASC-measured fall speeds compare well with Ka-band Atmospheric Radiation Measurement (ARM) Zenith Radar (KAZR) mean Doppler velocities only when winds are light (< 5 m s−1) and the MASC is shielded. MASC-measured fall speeds that do not match KAZR measured velocities tend to fall below a threshold value that increases approximately linearly with wind speed but is generally

scholarly journals Effect of a Support Tower on the Performance and Wake of a Tidal Current Turbine

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1059
Author(s):  
Zia Ur Rehman ◽  
Saeed Badshah ◽  
Amer Farhan Rafique ◽  
Mujahid Badshah ◽  
Sakhi Jan ◽  
...  
Keyword(s):  
Tidal Current ◽  
Tidal Energy ◽  
Coefficient Of Performance ◽  
Speed Ratio ◽  
Cfd Simulations ◽  
Ansys Cfx ◽  
Tidal Turbine ◽  
Computational Fluid Dynamics Cfd ◽  
Tidal Current Turbine ◽  
Current Turbine

Tidal energy is one of the major sources of renewable energy. To accelerate the development of tidal energy, improved designs of Tidal Current Turbine (TCT) are necessary. The effect of tower on performance and wake of TCT is investigated using Computational Fluid Dynamics (CFD) simulations. Transient analysis with transient rotor stator frame change model and shear stress transport turbulence model are utilized in ANSYS CFX. An experimentally validated numerical model with full scale tidal turbine with a blockage ratio of 14.27% and Tip Speed Ratio (TSR) 4.87 is used to simulate the effect of different tower diameters on performance and wake. The effect of different tower diameters is quantified in terms of coefficient of performance (CP). Coefficient of performance for a 3.5 m tower diameter is 0.472 which is followed by 3, 2.5 and 2 m with coefficients of performance of 0.476, 0.478 and 0.476 respectively. Similarly, the coefficient of thrust (CT) on the rotor for 3.5 m tower diameter is 0.902, for 3 m diameter 0.906 and for 2.5 and 2 m diameters are 0.908 and 0.906 respectively.

Computer Simulation and Modelling of Passive Humidification Device Cavity for Intensive Care Patient Medical Applications

2014 ◽  
Author(s):  
Mahmoud Shafik ◽  
Anne Lechevretel
Keyword(s):  
Heat Transfer ◽  
Intensive Care Patient ◽  
Care Patient ◽  
Medical Applications ◽  
Cfd Simulations ◽  
Moisture Exchange ◽  
Flow And Heat Transfer ◽  
Computational Fluid Dynamics Cfd ◽  
Heat And Moisture ◽  
Exchange Properties

This paper presents the research that has been undertaken into the passive humidification device cavity airflow structures and patterns. This was aiming to improve the device airflow, Heat and Moisture Exchange (HME) materials performance, for a greater patient care. However the objectives were to assist in understanding the optimal cavity structural geometries, generating improved airflow patterns over target HME material structures and consequently leading to improved heat and moisture exchange properties. Airflow studies of the device have been undertaken using the Computational Fluid Dynamics (CFD) interface of the ANSYS. The CFD package enables analysis of fluid flow and heat transfer. This paper presents the results of the CFD simulations carried out on different passive humidification device cavity designs and materials arrangements. An optimised design leading to enhanced airflow structures and patterns, heat and moisture properties of the device is also presented in this paper.

Numerical Simulations and Experiments on Gaseous Flow and Heat Transfer in Multiple Narrow Channels in Transition Region

2013 ◽  
Author(s):  
Yuming Chen ◽  
Christine Klein ◽  
Frederik Arbeiter ◽  
German Ibaceta
Keyword(s):  
Reynolds Number ◽  
Transition Region ◽  
Turbulence Models ◽  
Reynolds Numbers ◽  
Gamma Model ◽  
Cfd Simulations ◽  
Narrow Channels ◽  
Flow And Heat Transfer ◽  
Ansys Cfx ◽  
Test Module

The International Fusion Materials Irradiation Facility (IFMIF) is designated to generate a materials irradiation database for the future fusion reactors. The High Flux Test Module (HFTM) houses the test specimens which will be cooled with helium flows passing through several parallel narrow channels. The Reynolds numbers for individual sub-channels range from about 1000 to 8000. For most sub-channels the flow is in the transition region, which cannot be accurately predicted by using laminar or turbulence models. As a part of the HFTM validation activities, the thermo-hydraulic tests of a 1:1 single irradiation rig were carried out. The experiments also provide data for validating the CFD codes for using in the simulations of the whole HFTM. In this paper, the CFD simulations and experiments will be compared for helium flows at a Reynolds number between 3000 and 8000. The simulations were carried out with the commercial CFD code Ansys-CFX V14 using several turbulence models. It is found that, the CFX Gamma model with the transition onset Reynolds number of about 180 provides the best predictions for the transition flows.

scholarly journals Effect of Bolts on Flow and Heat Transfer in a Rotor–Stator Disk Cavity

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Sulfickerali Noor Mohamed ◽  
John W. Chew ◽  
Nicholas J. Hills
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Time Dependent ◽  
Navier Stokes ◽  
Cfd Simulations ◽  
Flow And Heat Transfer ◽  
Gap Ratio ◽  
Computational Fluid Dynamics Cfd ◽  
Dependent Flow ◽  
Insight Into

Previous studies have indicated some differences between steady computational fluid dynamics (CFD) predictions of flow in a rotor–stator disk cavity with rotating bolts compared to measurements. Recently, time-dependent CFD simulations have revealed the unsteadiness present in the flow and have given improved agreement with measurements. In this paper, unsteady Reynolds averaged Navier–Stokes (URANS) 360 deg model CFD calculations of a rotor–stator cavity with rotor bolts were performed in order to better understand the flow and heat transfer within a disk cavity previously studied experimentally by other workers. It is shown that the rotating bolts generate unsteadiness due to wake shedding which creates time-dependent flow patterns within the cavity. At low throughflow conditions, the unsteady flow significantly increases the average disk temperature. A systematic parametric study is presented giving insight into the influence of number of bolts, mass flow rate, cavity gap ratio, and the bolts-to-shroud gap ratio on the time-dependent flow within the cavity.

scholarly journals Experimental and CFD Simulations of the Aerosol Flow in the Air Ventilating the Underground Excavation in Terms of SARS-CoV-2 Transmission

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4743
Author(s):  
Tomasz Janoszek ◽  
Zbigniew Lubosik ◽  
Lucjan Świerczek ◽  
Andrzej Walentek ◽  
Jerzy Jaroszewicz
Keyword(s):  
Numerical Calculations ◽  
Mining Institute ◽  
Ventilation Network ◽  
Underground Excavation ◽  
In Situ Tests ◽  
Ansys Fluent ◽  
Aerosol Emission ◽  
Ansys Cfx ◽  
Computational Fluid Dynamics Cfd

The paper presents the results of experimental and model tests of transport of dispersed fluid droplets forming a cloud of aerosol in a stream of air ventilating a selected section of the underground excavation. The excavation selected for testing is part of the ventilation network of the Experimental Mine Barbara of the Central Mining Institute. For given environmental conditions, such as temperature, pressure, relative humidity, and velocity of air, the distribution of aerosol droplet changes in the mixture of air and water vapor along the excavation at a distance was measured at 10 m, 25 m, and 50 m from the source of its emission. The source of aerosol emission in the excavation space was a water nozzle that was located 25 m from the inlet (inlet) of the excavation. The obtained results of in situ tests were related to the results of numerical calculations using computational fluid dynamics (CFD). Numerical calculations were performed using Ansys-Fluent and Ansys-CFX software. The dimensions and geometry of the excavation under investigation are presented. The authors describe the adopted assumptions and conditions for the numerical model and discuss the results of the numerical solution.

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