SIMPLIFIED METHOD FOR MODELING SWIRL DIFFUSERS

How to model airflow discharged from diffuser is believed to be one of the key issues in ComputationalFluid Dynamics (CFD) applications to indoor air problem. Due to the complicated geometric feature andthe vortex-type airflow induced by swirl diffuser, simulating such a kind of diffuser is claimed to be achallenge. A simplified method of defining the boundary conditions at round swirl inlets is developedand introduced in this paper. With this method a round diffuser was divided into 6 triangular sectors withequal air discharge rate, while various air throw orientation angle was assigned to each sector. CFDsimulations were performed based on thermal and airflow boundary conditions recorded in a controlledenvironment chamber, which was equipped with both ceiling and floor mounted round diffusers.Comparisons between smoke airflow visualization and CFD predictions demonstrated theeffectiveness of the current simplified modeling method of swirl diffuser. On top of this, profiles oftemperature, air velocity, and CO2 concentration from measurements were also presented to validatethe CFD simulation results.