An experimental study on the evaluation of natural ventilation performance of a two-sided wind-catcher for various wind angles

Natural ventilation performance of a two-sided wind-catcher is investigated for various wind angles (α = 0°–90°) and wind speeds by experimental wind tunnel and smoke flow visualization. A 1:50 scale model of a real wind-catcher in the city of Yazd (Iran) is employed. The pressure coefficient as well as velocity are measured by pressure taps and hot-wire anemometer, respectively. The hot-wire results are used to evaluate the induced airflow rate and turbulence intensity. Smoke flow visualization techniques are employed to study the flow structure and patterns inside and outside of the wind-catcher. The results indicate that the wind direction has a large influence on the wind-catcher performance and the induced airflow rate increases with increasing the wind speed. The hot-wire results show that the transition angles of the house window and windward opening for all wind speeds occur at the wind angles of 39° and 55°, respectively. An excellent agreement is also found for these transition angles when they are determined by measured pressure coefficients. Based on measured quantities, it is found that the wind-catcher acts as a chimney for the wind angle larger than the windward transition angle (α = 55°) and the highest ventilation rate occurs at the wind angle of 90°.