Date of Award

12-2012

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical and Aerospace Engineering

Advisor(s)

Thong Q. Dang

Keywords

building aerodynamics, IAQ, inter-zonal airflows, natural ventilation, resistance device, wind pressure manipulation

Subject Categories

Mechanical Engineering

Abstract

This research investigates methods of manipulating building envelope wind pressure distribution for application in the natural ventilation of high-rise buildings. CFD simulations are employed to predict the wind pressure distribution around the building envelope. First, a 2-D CFD study is conducted to explore various techniques of manipulating the building envelope wind pressure distribution. This study indicates that the use of externally mounted flow-resistance devices is an effective method of manipulating the wind pressure distribution. It is demonstrated that this technique is well suited for application to buildings of streamlined cross-section (e.g. elliptical planform). Next, a 3-D CFD study is conducted in order to investigate the performance of the flow resistance device concept applied to a full-scale building. The results indicate that it is possible to significantly alter the pressure distributions at different heights of the building by utilizing continuous resistance devices. Manipulating the wind pressure distribution is shown to confer the ability to control the direction of the airflow exchange (i.e., intake v/s exhaust) in the interior zones of a building. The issue of partially polluted airflow exchange between occupied zones of a building is addressed, and a metric called ASHRAE-Equivalent Airflow is developed to assess the quality of ventilation provided under such conditions. A simple problem is formulated in order to demonstrate the application of this technique for the optimal control of natural ventilation. The results indicate that the resistance device concept may be well suited to meet the ventilation requirements in the building interior, especially when the demand for ventilation is non-uniformly distributed. This technique may be further augmented by allowing for control over the size of ventilation openings. Finally, a brief analysis of various energy consideration related to the application of natural ventilation is performed. It is seen that the energy consumption in a naturally ventilated building may be minimized by appropriately controlling the amount of airflow exchange depending on the external conditions. In addition, the use of wind turbines mounted on the building periphery could be beneficial as the flow resistance medium device may offset a significant fraction of the electrical energy consumption in the building.

Access

Open Access

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