Study on the effect of IJV supply terminal shape on airflow characteristics in a room with high heat load (ISHVAC2025)

In impinging jet ventilation (IJV) systems, supply terminal shape is a critical design factor. Although previous studies have shown that supply terminal shape affects indoor temperature and contaminant concentration distributions, the underlying aerodynamic mechanisms remain unclear. This numerical study investigates the mechanisms through which terminal shape influences the indoor environment. Three terminal shapes (0.75 m × 0.20 m, 1.00 m × 0.15, and 1.50 m × 0.10 m) were analysed at a supply flowrate of 600 m3/h with a single high-capacity heat source (1500 W), with particular attention to impinging-jet development and localised aerodynamics around the heat source. The results indicate that high-aspect-ratio terminals redistribute the supplied airflow and deliver greater directional momentum flux towards the heat source than low-aspect-ratio terminals. This greater momentum flux produces a broader high-velocity region and more pronounced flow separation around the heat source, generating a distinct downstream wake. The resulting regions of elevated turbulence appear to enhance ambient-air entrainment into the thermal plume and increase the plume flowrate. The increased plume flowrate reduces the stratification height and increases the average temperature and CO2 concentration. These findings provide useful insights and highlight that supply-terminal shape requires careful consideration in IJV system design.