Numerical study on flow distribution strategy of vertical multi-stage inclined slit ventilation system based on thermal buoyancy length scale

This study investigates a novel ventilation technology called vertical single-row inclined slit ventilation (VSISV). Numerical simulations were employed to analyse the effects of slit quantity, supply air flow and flow distribution strategies on indoor environment. Results show that increasing slit number improves vertical jet flow continuity but has limited effect on horizontal reach and overall temperature distribution. The VSISV system performs inadequately at low supply air flow rates, but as the supply flow increases, its performance gradually approaches that of the impinging jet ventilation (IJV) system. At high supply flow rates, its unique airflow circulation characteristics contribute to a more concentrated high-temperature distribution. By adjusting the thermal buoyancy length scale (lm) of the flow from the lowest slit to match that of the IJV system, an independent air supply flow distribution strategy for the slits in the VSISV system is proposed. This strategy significantly enhances the horizontal spread of the jet, thereby enhancing temperature uniformity, energy efficiency and indoor air quality. However, at high air supply rates, caution should be taken to prevent potential localised discomfort in the room’s front zone, such as increased draft rate (DR) and predicted mean vote (PMV) issues.