A multi-directional flap fin louver windcatcher: Experiment, numerical and field test investigations

Windcatchers, as natural ventilation apparatuses, are integrated into architectural designs to facilitate fresh air circulation, minimize energy expenditure, and occasionally, enhance indoor thermal comfort. However, their operational efficacy is often compromised by adverse meteorological conditions. To circumvent this limitation, researchers have been exploring the amalgamation of passive and low-energy heating, cooling, and dehumidification technologies. Despite these advancements, the majority of existing studies have not adequately addressed the impact of fluctuating wind conditions, which can potentially render windcatchers ineffective. In response to this gap, we propose an innovative windcatcher design equipped with flap fins at the inlet openings. This design ensures a consistent supply of fresh air, irrespective of wind direction, and facilitates the integration of passive and low-energy technologies. Drawing inspiration from the check valve mechanism, the flap fin design permits unidirectional wind flow into the windcatcher's supply channel, thereby ensuring that changes in wind direction do not affect the ventilation rate or the positioning of the supply and return channels. This, in turn, allows for the effective application of passive technologies. The flap fin, which operates via gravity and leverages wind pressure around the openings to regulate airflow, is lightweight. We developed an open wind tunnel and test room to experimentally assess the ventilation performance of the proposed windcatcher prototype. Additionally, a validated Computational Fluid Dynamics (CFD) model was constructed. Preliminary findings indicate that the ventilation performance of the flap fin louver windcatcher is independent of wind direction, as observed in both field tests and wind tunnel experiments. Furthermore, the use of lighter and longer fins appears to enhance the ventilation rate.