Interaction Mechanism and Trajectory Modeling of Dual Supply Jets in Graded Ventilation

Graded ventilation (GV) is an advanced air distribution for energy-efficient thermal comfort and air quality. This study investigates the interaction characteristics between the primary and secondary supply jets of GV to explain the underlying mechanisms of its high ventilation performances. The trajectories of the two supply air jests are quantified based on the two-step contour plot processing with criteria of the maximal air velocity and the lowest air temperature. Compared to the stratum ventilation, the velocity attenuation of the primary supply jet can be reduced by 3.35% - 15.29%. GV enhances energy efficiency and air quality, reducing energy consumption by 16.34% and increasing pollutant removal efficiency by 64.35%. Supply trajectory models for GV are developed. For the primary supply jet validation dataset, the developed model achieved R² values exceeding 0.90 for trajectory position, velocity, and temperature predictions, with corresponding RMSEs below 0.02 m, 0.14 m/s, and 0.42°C, respectively.