Experimental and large-eddy simulation study of swirling air jet: Application for the improvement of the spatial temperature homogeneity

In the present work, a swirl diffuser with a new design is proposed to be applied in the ventilation of living rooms, aiming to improve thermal comfort in an occupied area with a lower cost. For that, the effects of geometric parameters on a swirl air diffuser performance are experimentally and numerically investigated. To use an appropriate turbulence model that best reproduces the complex character of the swirl diffuser airflow for investigation, three turbulence models from the large-eddy simulation (LES) class—i.e., the Smagorinsky–Lilly (LES/S–L), the wall-adapting local eddy-viscosity (LES/WALE), and the kinetic-energy transport (LES/K–ET) turbulence models—are selected and tested. It is found that the three turbulence models are not able to predict simultaneously the thermal evolution of the flow in the entire jet domain. However, the results obtained with the LES/K–ET turbulence model are highly consistent with the experimental results. It can be concluded that the new design of the swirl air diffuser improves the spatial temperature homogeneity by spreading a significant air quantity over the room which, in turn, permits to obtain homogenized temperature in large spaces. The character of this jet type appears important and useful for the applications of heating, ventilation, and air conditioning (HVAC) systems.