Experimental study on flow field structure of ventilation space under colliding jets

In order to study the influence of the positions of the air supply outlet and return outlet on the indoor flow field structure, this paper builds a ventilation scale model experiment platform using multiple slots to impinge air supply, and uses the particle image velocimetry technique to study the velocity and turbulence information of the unstable airflow field in the multiple slot ventilation space under isothermal and non-isothermal conditions.The results show that under isothermal and non-isothermal conditions, the spatial distributions of flow field velocity, turbulent kinetic energy and vorticity in the air supply outlet section are similar, and the maximum values can reach 1.3 m/s, 0.1 m2/s2and 60 s-1, respectively. Two large-scale vortices are formed due to jet impingement, resulting in unstable flow field structure. In the CS4.5 section, the maximum flow field velocity, turbulent kinetic energy and vorticity can reach 0.9 m/s, 0.04 m2/s2and 30 s-1, respectively. In the CS3.5 section, the maximum velocity and vorticity appear near the wall, which are 0.42 m/s and 8 s-1, respectively, the maximum turbulent kinetic energy appears in the middle of the section, it is 0.13 m2/s2, and the large scale vortices are formed in the flow field.Under the non-isothermal condition, the medium and small scale vortices of the air supply outlet section and the CS3.5 section increase, while the large scale vortice decreases. Therefore, the thermal plume inhibits the large scale flow field structure and increases the small scale flow field structure.