Time Domain Analysis of the Temperatures in an Electrical Auxiliary Building Room

2009 ◽  
Author(s):  
Andron Creary ◽  
Matthew F. King ◽  
Matthew Langston ◽  
Cable Kurwitz ◽  
Paul Nelson ◽  
...  
Keyword(s):  
Air Temperature ◽  
Model Experiment ◽  
Time Domain Analysis ◽  
Lumped Parameter Model ◽  
Scale Model ◽  
Small Scale ◽  
Cfd Model ◽  
Air Temperatures ◽  
Lumped Parameter ◽  
Computational Fluid Dynamics Cfd

A computational fluid dynamics (CFD) model has been developed to predict air temperatures within the switchgear room environment of a nuclear plant’s Electronics Auxiliary Building (EAB). In order to validate the CFD model output, a scale model experiment has been developed using an analytical model to properly scale important EAB room parameters to allow small scale experiments to be performed for validation of the CFD model. The focus of this paper is the development of the methodology used to accurately predict the bulk air temperature or the EAB room. The CFD model is compared to a simple lumped parameter model as well as a scale model experiment. The scaling approach matches the eigenvalues of the lumped parameter model. An experiment based on this scaling approach was performed and compared with CFD output. The time predicted by the CFD model of the Electrical Auxiliary Building room for the average air temperature to increase from 17.7 °C (64 °F) to 40 °C (104 °F) is 23.5 minutes. The lumped parameter analytic solution produces a mean time of 22 minutes. The heat up time for the experiment matches the CFD model providing confidence in the fidelity of the CFD model.

scholarly journals Opening Size Effects on Airflow Pattern and Airflow Rate of a Naturally Ventilated Dairy Building—A CFD Study

2020 ◽  
Vol 10 (17) ◽  
pp. 6054
Author(s):  
Chayan Kumer Saha ◽  
Qianying Yi ◽  
David Janke ◽  
Sabrina Hempel ◽  
Barbara Amon ◽  
...  
Keyword(s):  
Size Effects ◽  
Scale Model ◽  
Airflow Rate ◽  
Gaseous Emissions ◽  
Cfd Model ◽  
Measuring Techniques ◽  
Transient Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Model Geometry ◽  
Cow Comfort

Airflow inside naturally ventilated dairy (NVD) buildings is highly variable and difficult to understand due to the lack of precious measuring techniques with the existing methods. Computational fluid dynamics (CFD) was applied to investigate the effect of different seasonal opening combinations of an NVD building on airflow patterns and airflow rate inside the NVD building as an alternative to full scale and scale model experiments. ANSYS 2019R2 was used for creating model geometry, meshing, and simulation. Eight ventilation opening combinations and 10 different reference air velocities were used for the series of simulation. The data measured in a large boundary layer wind tunnel using a 1:100 scale model of the NVD building was used for CFD model validation. The results show that CFD using standard k-ε turbulence model was capable of simulating airflow in and outside of the NVD building. Airflow patterns were different for different opening scenarios at the same external wind speed, which may affect cow comfort and gaseous emissions. Guiding inlet air by controlling openings may ensure animal comfort and minimize emissions. Non-isothermal and transient simulations of NVD buildings should be carried out for better understanding of airflow patterns.

scholarly journals Experimental verification of a CFD model for the closed plant factory under artificial lighting

2020 ◽  
Vol 213 ◽  
pp. 03013
Author(s):  
Wei Lu ◽  
Yiwen Hu ◽  
Shenghan Zhou ◽  
Xin Zhang ◽  
Quan Yuan ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Air Temperature ◽  
Experimental Verification ◽  
Cfd Model ◽  
Air Velocity ◽  
Artificial Lighting ◽  
Mean Relative Error ◽  
Plant Factory ◽  
Computational Fluid Dynamics Cfd ◽  
The Mean

A computational fluid dynamics (CFD) model for the closed plant factory under artificial lighting has been developed in this study, the experimental verification of CFD model with the air velocity value was compared with the measured air temperature value. The results showed that the mean relative error of validation with the air velocity was 15%, and comparable with experimentally observed air temperature profile inside the plant factory with RMSE of 3% which show the utility of CFD to study plant factory microclimatic parameters.

scholarly journals The Effect of Tree-Planting Patterns on the Microclimate within a Courtyard

2019 ◽  
Vol 11 (6) ◽  
pp. 1665 ◽  
Author(s):  
Junying Li ◽  
Jiying Liu ◽  
Jelena Srebric ◽  
Yuanman Hu ◽  
Miao Liu ◽  
...  
Keyword(s):  
Air Temperature ◽  
Local Heat Transfer ◽  
Field Measurements ◽  
Weather Conditions ◽  
Local Heat ◽  
Tree Planting ◽  
Cfd Model ◽  
Planting Pattern ◽  
Wind Velocities ◽  
Computational Fluid Dynamics Cfd

Current landscape design within a courtyard usually does not take into account the influence of the tree-planting pattern, which has an important influence on the outdoor microclimate and occupants’ thermal comfort. At present, the extent of the influence on the microclimate has not yet been made clear. Computational Fluid Dynamics (CFD) was employed to run this model under hot summer weather conditions. Field measurements validated the performance of the CFD model. This study conducted numerical simulations for five different tree-planting patterns, including (i) focused tree-planting (F), (ii) cornered tree-planting (C), (iii) multi-row tree-planting (R), (iv) surround tree-planting (S) and (v) no tree-planting (N). Our study found that the tree-planting pattern affects both the distribution of air temperature and the degree of local heat transfer. Specifically, the C, S and N patterns allow for higher ventilation in the studied courtyard, while the F and R patterns cause lower wind velocities and associated courtyard ventilation. The average air temperature for the C pattern is lower during summer afternoons than the other patterns. The wind flow pattern in the studied courtyard does not vary significantly with different tree-planting patterns. Nevertheless, the general relative humidity in the courtyard does not vary significantly with different tree-planting patterns, except for the N pattern. A future analysis is needed to investigate the mechanisms of the phenomenon.

Multiphase Computation of Cavitation Breakdown in Model and Prototype Scale Francis Turbines

2015 ◽  
Author(s):  
Daniel J. Leonard ◽  
Jules W. Lindau
Keyword(s):  
Large Scale ◽  
Scale Model ◽  
Cfd Model ◽  
Cfd Simulations ◽  
Qualitative And Quantitative ◽  
Machine Performance ◽  
Computational Fluid Dynamics Cfd ◽  
Stage Analysis ◽  
Reduced Scale ◽  
Francis Hydroturbine

Steady-periodic multiphase Computational Fluid Dynamics (CFD) simulations were conducted to capture cavitation breakdown in a Francis hydroturbine due to large-scale vaporous structures. A reduced-scale model and a full-scale prototype were investigated to display differences in vapor content and machine performance caused by lack of Reynolds and Froude similarity. The model scale efficiencies compared favorably (within 3%) to the experimental cavitation tests. The CFD model and prototype displayed distinct qualitative and quantitative differences as σ was reduced. A stage-by-stage analysis was conducted to assess the effect of cavitation on loss distribution throughout the machine. Furthermore, a formal mesh refinement study was conducted on efficiency and volume of vapor, with three mesh levels and Richardson extrapolation, to ensure convergence.

scholarly journals Modelling and Validation of Cavitating Orifice Flow in Hydraulic Systems

2021 ◽  
Vol 13 (13) ◽  
pp. 7239
Author(s):  
Paolo Casoli ◽  
Fabio Scolari ◽  
Massimo Rundo
Keyword(s):  
Lumped Parameter Model ◽  
Hydraulic Systems ◽  
Vena Contracta ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Orifice Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Set Up ◽  
Cfd Method ◽  
Hydraulic Valves

Cavitation can occur at the inlet of hydraulic pumps or in hydraulic valves; this phenomenon should be always avoided because it can generate abnormal wear and noise in fluid power components. Numerical modeling of the cavitation is widely used in research, and it allows the regions where it occurs more to be predicted. For this reason, two different approaches to the study of gas and vapor cavitation were presented in this paper. In particular, a model was developed using the computational fluid dynamics (CFD) method with particular attention to the dynamic modeling of both gaseous and vapor cavitation. A further lumped parameter model was made, where the fluid density varies as the pressure decreases due to the release of air and the formation of vapor. Furthermore, the lumped parameter model highlights the need to also know the speed of sound in the vena contracta, since it is essential for the correct calculation of the mass flow during vaporization. A test bench for the study of cavitation with an orifice was set up; cavitation was induced by increasing the speed of the fluid on the restricted section thanks to a pump located downstream of the orifice. The experimental data were compared with those predicted by CFD and lumped parameter models.

Cluster of High-Powered Racks Within a Raised-Floor Computer Data Center: Effect of Perforated Tile Flow Distribution on Rack Inlet Air Temperatures

2004 ◽  
Vol 126 (4) ◽  
pp. 510-518 ◽  
Author(s):  
Roger Schmidt ◽  
Ethan Cruz
Keyword(s):  
Data Center ◽  
Control Volume ◽  
Flow Distribution ◽  
Computer Code ◽  
Cfd Model ◽  
Computer Data ◽  
Air Temperatures ◽  
Finite Control ◽  
Computational Fluid Dynamics Cfd ◽  
Tile Flow

This paper focuses on the effect on rack inlet air temperatures as a result of maldistribution of airflows exiting the perforated tiles located adjacent to the fronts of the racks. The flow distribution exiting the perforated tiles was generated from a computational fluid dynamics (CFD) tool called Tileflow (trademark of Innovative Research, Inc.). Both raised floor heights and perforated tile-free areas were varied in order to explore the effect on rack inlet temperatures. The flow distribution exiting the perforated tiles was used as boundary conditions to the above-floor CFD model. A CFD model was generated for the room with electronic equipment installed on a raised floor. Forty racks of data processing (DP) equipment were arranged in rows in a data center cooled by chilled air exhausting from perforated floor tiles. The chilled air was provided by four A/C units placed inside a room 12.1 m wide×13.4 m long. Because the arrangement of the racks in the data center was symmetric, only half of the data center was modeled. The numerical modeling for the area above the raised floor was performed using a commercially available finite control volume computer code called Flotherm (trademark of Flomerics, Inc.). The flow was modeled using the k-e turbulence model. Results are displayed to provide some guidance on the design and layout of a data center.

Effect of Continuous Arterial Blood Flow of Intra-Aorta Pump on the Aorta - A Computational Study

2013 ◽  
Vol 275-277 ◽  
pp. 672-676 ◽  
Author(s):  
Yan Jiao Xuan ◽  
Yu Chang ◽  
Bin Gao ◽  
Kai Yun Gu
Keyword(s):  
Blood Flow ◽  
Computational Study ◽  
Lumped Parameter Model ◽  
Arterial Blood Flow ◽  
Human Aorta ◽  
Arterial Blood ◽  
Lumped Parameter ◽  
Inlet Flow Rate ◽  
Time Patterns ◽  
Computational Fluid Dynamics Cfd

In this study, a computational fluid dynamics (CFD) study based on a finite element method (FEM) was performed for the human aorta with four different flow time patterns (healthy to full intra-aorta pump support). Fully coupled fluid-solid interaction (FSI) simulation was used to investigate the flow profiles in the aortic arch and its branches where the maximum disturbed and non-uniform flow patterns, and the wall shear stress profiles on the same areas. The blood flow was assumed as a homogeneous, incompressible, and Newtonian fluid flow. Flow across four inlets of aortas was derived from a lumped parameter model (LPM). The inlet flow rate waveforms were divided by different blood assist index (BAI), and were calculated with the physiological information of a heart failure patient.

Cluster of High Powered Racks Within a Raised Floor Computer Data Center: Effect of Perforated Tile Flow Distribution on Rack Inlet Air Temperatures

2003 ◽  
Author(s):  
Roger Schmidt ◽  
Ethan Cruz
Keyword(s):  
Data Center ◽  
Control Volume ◽  
Flow Distribution ◽  
Computer Code ◽  
Cfd Model ◽  
Computer Data ◽  
Air Temperatures ◽  
Finite Control ◽  
Computational Fluid Dynamics Cfd ◽  
Tile Flow

This paper focuses on the effect on inlet rack air temperatures as a result of maldistribution of airflows exiting the perforated tiles located adjacent to the fronts of the racks. The flow distribution exiting the perforated tiles was generated from a computational fluid dynamics (CFD) tool called Tileflow (Trademark of Innovative Research, Inc.). Both raised floor heights and perforated tile free area were varied in order to explore the effect on rack inlet temperatures. The flow distribution exiting the perforated tiles was used as boundary conditions to the above floor CFD model. A CFD model was generated for the room with electronic equipment installed on a raised floor. Fourty racks of data processing (DP) equipment were arranged in rows in a data center cooled by chilled air exhausting from perforated floor tiles. The chilled air was provided by four A/C units placed inside a room 12.1 m wide × 13.4 m long. Since the arrangement of the racks in the data center was symmetric only one-half of the data center was modeled. The numerical modeling for above the raised floor was performed using a commercially available finite control volume computer code called Flotherm (Trademark of Flomerics, Inc.). The flow was modeled using the k-e turbulence model. Results are displayed to provide some guidance on the design and layout of a data center.

Understanding Tire Acoustics Through Computational Fluid Dynamics (CFD) of Grooves With Deforming Walls

2015 ◽  
Author(s):  
Prashanta Gautam ◽  
Abhilash J. Chandy
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Stokes Equations ◽  
Road Traffic ◽  
Small Scale ◽  
Road Traffic Noise ◽  
Noise Generation ◽  
Cfd Model ◽  
Computational Fluid Dynamics Cfd ◽  
Generation Mechanisms

Reducing tire noise has been a topic of increased focus in the recent years in industrial countries in order to decrease road traffic noise. Computational fluid dynamics (CFD) simulations conducted using ANSYS FLUENT are presented here to provide a better understanding of the small-scale noise generation mechanisms due to air-pumping at the tire-road interface. The CFD model employs a large eddy simulation (LES) turbulence modeling approach, where the filtered compressible Navier-Stokes equations are solved for simple groove geometries with a moving bottom wall that represents the deformation due to the tire movement along the road surface. A horizontally moving wall is used to represent the motion of the tire groove in and out of the contact patch while the deformation of the groove is prescribed. Temporal and spatially accurate pressure fluctuations are utilized to determine sound pressure levels and dominant frequencies. In addition to an understanding of noise generation mechanisms in such grooves, the CFD model developed here can potentially provide a series of control parameters that can help optimize the tire performance in terms of tire acoustics.

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