An air supply mode based on vortex ring structures was proposed to deliver fresh air for good indoor air quality. This study focused on the influence of air supply parameters, including formation time (T*), supply air velocity (U), and supply air temperature difference (ΔT), on the fresh air delivery performance of an air vortex ring using numerical simulations. The cross-sectional average mass fraction of fresh air (C) was proposed to evaluate the fresh air delivery performance of the air vortex ring supply. The results showed that the convective entrainment of the vortex ring resulted from the combined effect of the induced velocity generated by the rotational motion of the vortex core and the negative pressure zone. When the formation time T* < 3.5, C increases with an increase in the formation time but decreases with an increase in the formation time for T* > 3.5. The variation in C is insignificant for U < 3 m/s or U > 3 m/s but decreases with an increase in the supply air temperature difference (ΔT). Thus, the optimal air supply parameters for air vortex ring supply are identified as T* = 3.5, U = 3 m/s, ΔT = 0 °C. Compared with the traditional circular and square free air jets, within 25D (D: the diameter of air supply inlet) downstream from the air inlet, the fresh air delivery performance of the air vortex ring supply is increased by a maximum of nearly 200 %, with an average improvement of approximately 120 %.
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