Validation of simulated velocity distribution in isothermal mixing ventilation cases with particle streak tracking

Abstract

This is a validation study for the velocity distribution in mixing ventilation. Two different supply air diffusers a slot and a swirl diffuser form two different room airflows. For the swirl diffuser two different and for the slot diffuser five different exhaust positioning are tested numerically and experimentally. A comparison of the flow structure shows good agreement between simulation and experiment for six air changes per hour, but not for the lower air change rate of 1.5 per hour. The velocity deviations between experiment and simulation are higher for the swirl diffuser. These exist partly due to the experimental methodology, but also due to an overestimation of the supply air momentum. Thus, further sensitivity investigations are carried out for the swirl diffuser. The overestimation of the supply air momentum depends mainly on a geometric model error in the computational fluid dynamics simulation. A comparison of different turbulence models confirms the advantages of the RST elliptic blending turbulence model over the k-epsilon realizable model for the swirl diffuser case.