Study of the Airflow Structure in Cross-Ventilated Rooms based on a Full-Scale Model Experiment

Cross ventilation to reduce cooling energy is one of the most important techniques for maintaining acomfortable indoor environment in hot and mild seasons. However, at present, it is difficult to design the indoor environment under cross ventilation because there is insufficient knowledge to evaluate the effect of cross ventilation quantitatively. To develop an understanding of the flow characteristics a full-scale model experiment was performed in a large wind tunnel to examine airflow properties in a cross-ventilated space.The purpose of this paper is to clarify the airflow structure in the cross-ventilated room in relation to wind direction. The key factors determining the airflow structure in the space were found to be: the main current region, rebounding and changing flow direction, deflected flow, surface flow and circulating flow. It was observed that the main air current tends to travel in a straight line until it collides with obstacles. On collision, the flow changes direction and deflected flows are formed over and/or under the main current. When there is enough space alongside the main current region, a circulating flow is formed in each room. The room mean velocity was found to be dependent on the path of the air current. When the main current is well defined, a relatively low value of mean velocity is observed. When the main current is divided, the room containing the inflow opening has a relatively high velocity.