scholarly journals Assessment for the Age-Of-The-Air and Ventilation Efficiency in Confined Outdoor Spaces through Computational Fluid Dynamics Techniques

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1932 ◽  
Author(s):  
Miguel Padilla-Marcos ◽  
Meiss Alberto
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Urban Design ◽  
Considerable Improvement ◽  
Outdoor Air ◽  
Outdoor Spaces ◽  
Ventilation Efficiency ◽  
Wind Exposure ◽  
The Mean ◽  
Definition Of

An experimentally validated numerical method for evaluating the suitability of an urban design with regard to its capacity to provide the optimum air quality for its occupants through the confined outdoor spaces is proposed. Eight possible confined outdoor spaces are defined according to their position with regard to the built elements, laterally delimited by the envelope surfaces of the neighbouring buildings. This work focuses on the definition of a procedure capable of analysing outdoor air change quality according to the age-of-the-air concept. The obtained results show that the confined outdoor spaces that are exposed to the wind action are more predisposed to reduce the mean age-of-the-air that they contain. For the analysed cases, a considerable improvement of up to 78.68% in the air change quality can be obtained by taking into account wind exposure criteria in relation to its shape and urban density, which is classified for this purpose.

Efficiency limits of fans

2019 ◽  
Vol 234 (5) ◽  
pp. 739-748
Author(s):  
Konrad Bamberger ◽  
Thomas Carolus
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Geometrical Parameter ◽  
The Self ◽  
Complex Geometries ◽  
Relevant Parameter ◽  
Optimization Scheme ◽  
Loss Models ◽  
Definition Of

The purpose of this work is to identify upper efficiency limits of industrial fans such as axial rotor-only fans, axial with guide vanes, centrifugal rotor-only and centrifugal with volute. The efficiency limit is always a function of the class, the design point within the class and the definition of efficiency (total-to-static and total-to-total). The characteristic Reynolds number is another relevant parameter. First, based on analytical and empirical loss models, a theoretical efficiency limit is estimated. A set of idealizing assumptions in the loss models yields efficiencies which are assumed to be an insuperable limit but may be unrealistically high. Second, more realistic efficiency limits are estimated using a computational fluid dynamics-based optimization scheme, seeking for the best designs and hence the maximum achievable efficiencies in all classes. Given the self-imposed constraints in the geometrical parameter space considered, the thus-obtained practical efficiency limits can only be exceeded by admitting more complex geometries of the fans.

scholarly journals Analysis on Ventilation Efficiency of Standard Duck House using Computational Fluid Dynamics

2015 ◽  
Vol 57 (5) ◽  
pp. 51-60 ◽  
Author(s):  
Uk-Hyeon Yeo ◽  
Ye-Seul Jo ◽  
Kyeong-Seok Kwon ◽  
Tae-Hwan Ha ◽  
Se-Jun Park ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Ventilation Efficiency

Computational fluid dynamics evaluation of the furniture arrangement for ventilation efficiency

2018 ◽  
Vol 39 (5) ◽  
pp. 557-571 ◽  
Author(s):  
Susana Hormigos-Jimenez ◽  
Miguel Ángel Padilla-Marcos ◽  
Alberto Meiss ◽  
Roberto Alonso Gonzalez-Lezcano ◽  
Jesús Feijó-Muñoz
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Energy Efficiency ◽  
Indoor Air ◽  
Tracer Gas ◽  
Steady State Method ◽  
Air Movement ◽  
Ventilation Efficiency ◽  
State Method ◽  
Furniture Arrangement

People spend most of their time indoors; therefore, maintaining a good indoor air quality and meeting the requirements of comfort and energy efficiency are essential. One of the most widespread strategies to achieve this objective is improving ventilation efficiency; therefore, the main aim of this study was to show an optimization of the ventilation efficiency, in a specific room, considering 47 variations (case studies) in the furniture arrangement. For this purpose, a numerical analysis using computational fluid dynamics techniques, validated by the tracer gas decay technique, was used to assess the distribution of the age of air within the space. The concept of “age of air” was implemented in the computational fluid dynamics code through user-defined functions, using the steady-state method based on the resolution of a transport equation for an additional scalar. Variations up to 5.75% in the ventilation efficiency between the cases studied have been achieved. It is concluded that an improvement up to 1.65% can be obtained when the elements of the study are introduced in a way that facilitates the air movement towards the exhaust; therefore, improvement of the ventilation efficiency through specific furniture distributions is possible, although not significant, according to the outcomes.

Air Flow Simulation in High-Pressure Fan with Splitter Blade

2013 ◽  
Vol 805-806 ◽  
pp. 1730-1735
Author(s):  
Xiao Lin Wang ◽  
Ding Hua Yang ◽  
Gen Sheng Yang ◽  
Zhong Li ◽  
Jian Feng Li ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
High Pressure ◽  
Total Pressure ◽  
Unstructured Grids ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Turbulent Model ◽  
Centrifugal Blower ◽  
The Mean

In the process of fans design, splitter blades could be adopted in the middle of rotator to improve the performance of fan. In order to understand the flow pattern in the high-pressure centrifugal blower of 9-26type with splitter blade thoroughly, computational fluid dynamics Fluent is applied and the three dimensional air flows in the fan is numerically simulated and analyzed. The calculating results showed that under the same condition, the flux of the fan was improved 5%approximately and the mean total pressure at outlet of the fan was improved 10% because of the splitter blade, the length of the splitter blade affected the flux either. Standard turbulent model and unstructured grids are applied in computation. The results of calculation can good helpful for people to improve the performance of the fan.

Perspective: Validation—What Does It Mean?

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Patrick J. Roache
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Top Down ◽  
Bottom Up ◽  
Definition Of ◽  
Journal Policies

Ambiguities, inconsistencies, and recommended interpretations of the commonly cited definition of validation for computational fluid dynamics codes/models are examined. It is shown that the definition-deduction approach is prone to misinterpretation, and that bottom-up descriptions rather than top-down legalistic definitions are to be preferred for science-based engineering and journal policies, though legalistic definitions are necessary for contracts.

scholarly journals Influence of Parapets on Wave Overtopping on Mound Breakwaters with Crown Walls

2019 ◽  
Vol 11 (24) ◽  
pp. 7109 ◽  
Author(s):  
Jorge Molines ◽  
Arnau Bayon ◽  
M. Esther Gómez-Martín ◽  
Josep R. Medina
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Laboratory Tests ◽  
Cfd Model ◽  
Wave Overtopping ◽  
Numerical Tests ◽  
Computational Fluid Dynamics Cfd ◽  
The Mean

Background literature on the influence of parapets on the overtopping of mound breakwaters is limited. In this study, numerical tests were conducted using computational fluid dynamics (CFD) to analyze the influence of nine crown wall geometries (seven with parapets). The CFD model was implemented in OpenFOAM® and successfully validated with laboratory tests. A new estimator of the dimensionless mean wave-overtopping discharges (logQ) on structures with parapets is proposed. The new estimator depends on the estimation of logQ of the same structure without a parapet. The effects on wave overtopping of the parapet angle (εp), parapet width (wp), and parapet height (hp) were analyzed. Low values of εp and wp/hp ≈ 1 produced the highest parapet effectiveness to reduce the mean wave-overtopping discharges.

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