Improving Tesla valve shape within fluid diode plates for building ventilation

In natural ventilation, indoor airflow should be utilized strategically to enhance indoor air quality, wherein planning and controlling proper ventilation routes are important topics. This study explores fluid diode plates (FDPs) based on the Tesla valve, aiming for passive ventilation route control. The Tesla valve provides different airflow resistances (i.e., pressure loss) when air passes through it in forward and reverse directions. This property can be quantified by the ratio of pressure losses in those directions. First, a series of computational fluid dynamics (CFD) simulations was conducted to reveal the relationships between the pressure loss ratio and key geometric parameters of the Tesla valve. The ratio increased with increased bypass channel height and decreased with increased main channel length or slope. When the main channel length and baffle thickness were fixed, a maximum ratio was found for a slope and bypass channel height set. This maximum ratio provided by the optimal shape (Shape 2) was double that of the shape proposed in a previous study (Shape 1). Secondly, the FDPs with Shapes 1 and 2 were numerically installed in a typical building model to compare their flow control performance in a cross -ventilation scenario by three-dimensional CFD simulations. The ventilation rate differed with multidirectional FDP installations at the building's openings, and the difference was more significant with increased external wind speed. At most external wind speeds considered, Shape 2 outperformed Shape 1, providing 20-30 % more and 10-15 % less ventilation than Shape 1 in the forward and reverse directions, respectively.