Measurement and prediction of the indoor airflow in a room ventilated with a commercial wind tower

• CFD and wind tunnel tools were used to perform full analysis of the indoor airflow.
• Good agreement was found between CFD and experimental data with average error of 10%.
• CFD code could be useful for the prediction of the MAA in buildings with wind towers.
• MAA analysis indicated that more mixing was present at higher external wind speeds.
• Values of the ACE in the space were generally close to 1.0 meaning good mixing.

This paper introduces a method for a full assessment of the internal air movement characteristics in a room ventilated with a commercial wind tower using scaled wind tunnel and computational fluid dynamics (CFD) analysis. An accurate geometrical representation of the experimental situation was recreated in the CFD simulation. The experimental investigation was carried out using a closed-loop low speed wind tunnel and the indoor air flow distribution was measured and compared with the CFD analysis. Good correlation between the numerical and experimental results was observed (10% average error). Flow visualisation was also conducted to further analyse the airflow structure within the room. The work assessed several ventilation parameters to describe the indoor airflow characteristics such as the mean age of air (MAA), air change rate, and air change effectiveness (ACE). The MAA was calculated using the steady-state method, by solving an additional partial differential equation describing the transport of the scalar “age of air”. The numerical analysis of the MAA allowed to detect less or insufficiently ventilated areas. The CFD code could be useful for the calculation of the MAA and ACE, allowing reduction in time and cost in the evaluation of indoor air quality in buildings ventilated with wind tower or similar device.

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