Experiment and Numerical Investigation of a Novel Flap Fin Louver Windcatcher for Multidirectional Natural Ventilation and Passive Technology Integration

Natural ventilation devices such as windcatchers are incorporated into the building design to provide fresh air supply, energy consumption reduction and, in some cases, indoor thermal comfort. However, unfavourable weather conditions limit the operation period of windcatchers, and researchers have explored the integration of passive/low-energy heating, cooling and dehumidification technologies to address this issue. While previous works have addressed the cooling or pre-heating of the supply air, most have not investigated the impact of changing wind conditions which, in some cases, render the windcatcher ineffective. Thus, a novel windcatcher with inlet openings equipped with flap fins was proposed to provide a fresh air supply irrespective of the wind direction and allow for passive/low-energy technology integration. Inspired by the check valve device, the flap fin mechanism allows wind to flow only one way into the windcatcher's supply channel. Hence, changing wind directions would not affect the ventilation rate and the location of the supply and return channels, so passive technologies can be applied effectively. The lightweight flap fin operates via gravity and takes advantage of the wind pressure around the openings to control the airflow. An open wind tunnel and test room were developed to experimentally evaluate the ventilation performance of the proposed windcatcher prototype, and a validated Computational Fluid Dynamic (CFD) model was developed. The results showed that the ventilation performance of the flap fin louver windcatcher was independent of the wind direction in the field test and wind tunnel experiment, and the use of lighter and longer fins would enhance the ventilation rate.