Research on Flow Resistance Characteristics with Different Window/Door Opening Angles

Airflow rate through buildings can depend in part on the degree of opening of various doors and windows. A better understanding of flow resistance characteristics under different window/door opening angles can help us better predict the airflow rate in buildings. Additionally, better understanding of flow characteristics can enable better natural ventilation control strategies. We examined the discharge coefficient and loss coefficient of a window/door with differing degrees of opening through both wind tunnel testing and computational fluid dynamic (CFD) simulation. We were able to match simulated and tested pressure differences across the opening under certain airflow rates. The simulated results for discharge coefficient and loss coefficient matched well with the test data. Results showed that discharge coefficient increases with increasing degree of window/door opening, while the loss coefficient decreases. Additionally, the discharge coefficient Cd and loss coefficient ζ are all power-correlated with the window/door opening angle θ. The loss coefficient decreases sharply with the increasing of the window/door opening angle θ when θ is smaller than 30° and plateaus when θ is larger than 30°, thus showing that doors and windows do not need to be fully open for optimal natural ventilatio

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