Numerical Simulation and Analysis of the Two-Sided Windcatcher Inlet\Outlet Effect on Ventilation Flow Through a Three Dimensional Room

2014 ◽  
Author(s):  
Amirreza Niktash ◽  
B. P. Huynh
Keyword(s):  
Flow Velocity ◽  
Flow Pattern ◽  
Natural Ventilation ◽  
Three Dimensional ◽  
Interior Space ◽  
Different Types ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Cfd Method ◽  
Living Area

A windcatcher is a structure placed on the roof of a building for providing natural ventilation for interior space working by wind power. It draws out the inside stale air to the outside and supplies the outside fresh air for the building’s interior space. In this paper, the effect of different types of windcatcher’s inlet\outlet on the air flow, flow velocity and flowrate through a three-dimensional room fitted with a two-sided windcatcher is observed numerically, using a commercial computational fluid dynamics (CFD) software package. The standard RANS K-ε CFD method is used in the simulations. The flow pattern, flow velocity and flowrate of the inside ventilation flow is considered for the six different types of a two-sided windcatcher’s inlet\outlet. It is found that the shape of the inlet\outlet of windcatcher strongly affects flow pattern, flow velocity and flowrate and the performance of square windcatcher is higher than the circular one specially in ventilating the living area (lower part) of a room.

scholarly journals ICCM2015: A Comparison of RANS and LES Computational Methods in Analyzing Ventilation Flow Through a Room Fitted with a Two-Sided Windcatcher

2017 ◽  
Vol 14 (03) ◽  
pp. 1750021 ◽  
Author(s):  
A. Niktash ◽  
B. P. Huynh
Keyword(s):  
Natural Ventilation ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Interior Space ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Cfd Method ◽  
Good Agreement

A windcatcher is a structure for providing natural ventilation using wind power; it is usually fitted on the roof of a building to exhaust the inside stale air to the outside and supplies the outside fresh air into the building interior space working by pressure difference between outside and inside of the building. In this paper, the behavior of free wind flow through a three-dimensional room fitted with a centered position two-canal bottom shape windcatcher model is investigated numerically, using a commercial computational fluid dynamics (CFD) software package and LES (Large Eddy Simulation) CFD method. The results have been compared with the obtained results for the same model but using RANS (Reynolds Averaged Navier–Stokes) CFD method. The model with its surrounded space has been considered in both method. It is found that the achieved results for the model from LES method are in good agreement with RANS method’s results for the same model.

Numerical Study of Ventilation Flow Through a Two Dimensional Room Fitted With a Windcatcher

2011 ◽  
Author(s):  
A. R. Niktash ◽  
B. P. Huynh
Keyword(s):  
Flow Velocity ◽  
Flow Pattern ◽  
Software Package ◽  
Natural Ventilation ◽  
Numerical Study ◽  
Two Dimensional ◽  
Inlet Velocity ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Living Area

A windcatcher is a natural ventilation device fitted on the roof of a building and divided internally into two halves to deliver fresh outside air into the building’s interior, and induce the stale air to the outside, working by pressure difference between outside and inside of the building. In this work, air flow through a two-dimensional but real-sized room fitted with a windcatcher is investigated numerically, using a commercial computational fluid dynamics (CFD) software package. The standard K-ε turbulence model is used. Flow pattern and flow velocity are considered in terms of the windcatcher’s location, inlet velocity, the shape of the windcatcher’s bottom and the length of the windcatcher’s bottom. It is found that when inlet velocity is not too low, the windcatcher’s shape at its bottom strongly affects flow pattern and flow velocity in the room. This leads to a way of improving the windcatcher’s effectiveness in ventilating the living area (lower part) of a room.

IMPROVEMENT OF THERMAL COMFORT INSIDE A MOSQUE BUILDING

2016 ◽  
Vol 78 (8-4) ◽  
Author(s):  
Fawaz Ghaleb Noman ◽  
Nazri Kamsah ◽  
Haslinda Mohamed Kamar
Keyword(s):  
Thermal Comfort ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Side Wall ◽  
The West ◽  
Cfd Simulations ◽  
Interior Space ◽  
Flow Simulations ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

A combined natural ventilation and mechanical fans are commonly used to cool the interior space inside the mosques in Malaysia. This article presents a study on thermal comfort in the Al-Jawahir Mosque, located in Johor Bahru, Malaysia. The objective is to assess the thermal comfort inside the mosque under the present ventilation system by determining the Predicted Mean Vote (PMV) and the Predicted Percentage of Dissatisfied (PPD). These values were then compared to the limits stated in the ASHRAE Standard-55. It was found that the PMV varies from 1.68 to 2.26 while the PPD varies from 61% to 87%. These show that the condition inside the mosque is quite warm. Computational fluid dynamics (CFD) method was used to carry out flow simulations, to identify a suitable strategy to improve the thermal comfort inside the mosque. Results of CFD simulations show that installing four exhaust fans above the windows on the west-side wall of the mosque is the most effective strategy to improve the thermal comfort inside the mosque. Both the PMV and PPD values can potentially be reduced by more than 60%.

Simulation Study on Ventilation & Cooling for an Indoor Substation

2014 ◽  
Vol 672-674 ◽  
pp. 1700-1707 ◽  
Author(s):  
Rui Xu ◽  
Zhong Min Mei ◽  
Ting Fang Yu
Keyword(s):  
Natural Ventilation ◽  
Three Dimensional ◽  
Organization Design ◽  
Temperature Fields ◽  
Design Parameters ◽  
Air Distribution ◽  
Safety And Reliability ◽  
Computational Fluid Dynamics Cfd ◽  
Dimensional Simulation ◽  
Cfd Method

— Based on natural ventilation design scheme for an indoor substation, different air distribution schemes were obtained by changing height and size of air inlets and outlets. For indoor substation, three-dimensional simulation of air distribution was conducted by using Computational Fluid Dynamics (CFD) method. Ventilation & cooling effect of different indoor ventilation schemes were simulated with software (Fluent). By analyzing velocity fields and temperature fields, influences of different design parameters on safety and reliability of main transformer room of indoor substation were compared and analyzed in details. Additionally, characteristics and change rules of air distribution with different parameter variations were concluded. Considerations of ventilation organization design for main transformer room of indoor substation and recommendation for better air distribution schemes were provided. The research results also offered some guidance for design and renovation of ventilation & cooling projects of indoor substation.

Numerical Simulation of the Impact of Both Air Conditioning System and Train’s Movement on Platform Air Temperature Distribution

2008 ◽  
Author(s):  
Hui Yang ◽  
Li Jia ◽  
Lixin Yang
Keyword(s):  
Air Temperature ◽  
Air Conditioning ◽  
Natural Ventilation ◽  
Three Dimensional ◽  
Ventilation Mode ◽  
Piston Effect ◽  
Air Conditioning System ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
The Impact

The three dimensional air temperature distributions on subway platform under both natural ventilation mode and over-platform supply/ under-platform exhaust (OSUE) air conditioning system were simulated during a single train entering, staying and departing processes by using Computational Fluid Dynamics (CFD) method. On basis of the simulation, the comprehensive influences of both the train’s piston effect and the air conditioning mode on the air environment in different part of the platform were analyzed.

The Effect of Bench Arrangements on the Natural Ventilation of a Multispan Greenhouse

2013 ◽  
Author(s):  
Sunita Kruger ◽  
Leon Pretorius
Keyword(s):  
Fluid Dynamics ◽  
Natural Ventilation ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Low Velocity ◽  
Lower Velocity ◽  
Cfd Models ◽  
Temperature Distributions ◽  
Computational Fluid Dynamics Cfd ◽  
Plant Level

In this paper, the influence of various bench arrangements on the microclimate inside a two-span greenhouse is numerically investigated using three-dimensional Computational Fluid Dynamics (CFD) models. Longitudinal and peninsular arrangements are investigated for both leeward and windward opened roof ventilators. The velocity and temperature distributions at plant level (1m) were of particular interest. The research in this paper is an extension of two-dimensional work conducted previously [1]. Results indicate that bench layouts inside the greenhouse have a significant effect on the microclimate at plant level. It was found that vent opening direction (leeward or windward) influences the velocity and temperature distributions at plant level noticeably. Results also indicated that in general, the leeward facing greenhouses containing either type of bench arrangement exhibit a lower velocity distribution at plant level compared to windward facing greenhouses. The latter type of greenhouses has regions with relatively high velocities at plant level which could cause some concern. The scalar plots indicate that more stagnant areas of low velocity appear for the leeward facing greenhouses. The windward facing greenhouses also display more heterogeneity at plant level as far as temperature is concerned.

scholarly journals A computational investigation of the hydrodynamics of the Badush dam in northern Iraq

2018 ◽  
Vol 240 ◽  
pp. 04009
Author(s):  
Younis Saida Saeedrashed ◽  
Ali Cemal Benim
Keyword(s):  
Three Dimensional ◽  
Free Surface Flow ◽  
Surface Flow ◽  
Dam Failure ◽  
Northern Iraq ◽  
Digital Elevation ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Through ◽  
Elevation Model ◽  
Bottom Outlets

A computational analysis of the hydrodynamics of the Badush dam in Iraq is presented, which is planned to be reconstructed as a repulse dam, to prevent the Mosul city, in case of a failure of the Mosul dam. Computational Fluid Dynamics (CFD) is applied in combination with Geometric Information System (GIS) and Digital Elevation Model (DEM). In the first part of the study, a hydrologic study of a possible Mosul dam failure is performed, predicting the important parameters for a possible flooding of Mosul city. Here, a two-dimensional, depth-averaged shallow water equations are used to formulate the flow. Based on GIS and DEM, the required reservoir size and the water level of the Badush dam are predicted, for its acting as a repulse dam. Subsequently, a computational model of the reconstructed Badush dam is developed, combining the proposed construction with the local geographic topology to achieve a perfect fit. Finally, the water flow through the bottom outlets and stilling basin of the proposed dam is calculated by an unsteady, three-dimensional CFD analysis of the turbulent, free-surface flow. The CFD model is validated by comparing the predictions with measurements obtained on a physical model, where a quite satisfactory agreement is observed.

scholarly journals Feasible Concept of an Air-Driven Fan with a Tip Turbine for a High-Bypass Propulsion System

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3350 ◽  
Author(s):  
Guoping Huang ◽  
Xin Xiang ◽  
Chen Xia ◽  
Weiyu Lu ◽  
Lei Li
Keyword(s):  
Fluid Dynamics ◽  
Carbon Dioxide Emissions ◽  
Three Dimensional ◽  
Propulsion System ◽  
Navier Stokes ◽  
Three Dimensional Flow ◽  
Low Pressure Turbine ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Bypass Ratio

The reduction in specific fuel consumption (SFC) is crucial for small/mid-size cost-controllable aircraft, which is very conducive to reducing cost and carbon dioxide emissions. To decrease the SFC, increasing the bypass ratio (BPR) is an important way. Conventional high-BPR engines have several limitations, especially the conflicting spool-speed requirements of a fan and a low-pressure turbine. This research proposes an air-driven fan with a tip turbine (ADFTT) as a potential device for a high-bypass propulsion system. Moreover, a possible application of this ADFTT is introduced. Thermodynamic analysis results show that an ADFTT can improve thrust from a prototype turbofan. As a demonstration, we selected a typical small-thrust turbofan as the prototype and applied the ADFTT concept to improve this model. Three-dimensional flow fields were numerically simulated through a Reynolds averaged Navier-Stokes (RANS)-based computational fluid dynamics (CFD) method. The performance of this ADFTT has the possibility of amplifying the BPR more than four times and increasing the thrust by approximately 84% in comparison with the prototype turbofan.

Numerical Simulation of the Laminar Flow Field in Stirred Tank with Double Layer Combined Impeller Stirring Eccentrically

2015 ◽  
Vol 779 ◽  
pp. 125-132
Author(s):  
Ying Na Liang
Keyword(s):  
Flow Field ◽  
Double Layer ◽  
Three Dimensional ◽  
Stirred Tank ◽  
Flow Structures ◽  
Practical Application ◽  
Three Dimensional Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Multiple Reference

Computational fluid dynamics (CFD) method was applied to study the flow field in cylindrical stirred tank mixing non-Newtonian fluid with double layer combined impeller of upper-straight-blade and lower-inclined-blade. The laminar model and the multiple reference frame (MRF) were employed to simulate the three-dimensional flow field in stirred tank with double layer combined impeller rotating at a constant speed of 200 r/min mixing the mixture of glycerin and water centrally、eccentrically and relative eccentrically, and three different flow structures in stirred tank were obtained. Analyzing the velocity vectors, the velocity contours and the axial、radial and tangent velocity distribution curves, the rule of velocity field with the blade combined form and the stirring structure was discussed. The research provided the valuable reference for the design and practical application of the laminar stirred tank.

Modeling of Buoyancy-Driven Natural Ventilation in Workshop: Optimization of Distance between Heat Source and Ground

2012 ◽  
Vol 170-173 ◽  
pp. 2579-2582 ◽  
Author(s):  
Ya Xin Su ◽  
A Long Su ◽  
Xin Wan
Keyword(s):  
Heat Source ◽  
Indoor Air ◽  
Energy Cost ◽  
Lower Energy ◽  
Natural Ventilation ◽  
Waste Heat ◽  
Heat Sources ◽  
Hot Air ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method

Natural ventilation is suitable for application to workshops with heat sources to keep good indoor air quality at lower energy cost. In this paper, the authors numerically investigated the buoyancy-driven natural ventilation in a workshop with heat source based on computational fluid dynamics (CFD) method. The effect of the distance between heat source and ground on the air flow and temperature distribution was examined. Results showed that the average air temperature at operation zone could be effectively reduced when the distance between heat source and ground increased. The temperature field in the upper zone of the workshop was improved by diminishing the hot air zone near the ceiling and the waste heat directly going into the operation zone decreased when the distance between heat source and ground increased.

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