Unsteady CFD simulations for prediction of airflow close to a supply device for displacement ventilation
2014 (English)In: Indoor Air 2014 - 13th International Conference on Indoor Air Quality and Climate, 2014, 47-54 p.Conference paper (Refereed)
Modern diffusers applied in the field of ventilation of rooms are often complex in terms of geometry, including perforated plates, dampers, guide rails, curved surfaces and other components inside the diffuser, with the intention to create satisfying thermal comfort for the occupants. Also connecting ducts can be different for the same diffuser in different situations, affecting the supply velocity profile. It is obvious that simulation of airflow and air temperature particularly in rooms with displacement ventilation is very troublesome, particularly if the near-zone of the diffuser is of interest. Experiments commonly indicate very high turbulence intensities in the near-zone of displacement ventilation supply devices, especially close to the floor where high mean flow gradient occurs. This indicates that the air flow from inlet devices designed for displacement ventilation might be very unstable; the position of the stream leaving the diffuser and entering the room is changing with time, hence diffusion of momentum and temperature are increased. This effect is not captured in RANS simulations, since it is performed with the assumption of time-independent conditions. In this paper URANS simulations were performed for prediction of velocity and temperature distribution close to a complex air supply device in a room with displacement ventilation. The presented study show that unsteady simulations with the realizable turbulence k-ε model generates too high eddy viscosity and therefore damps out the unsteadiness of the flow especially inside the diffuser.
Place, publisher, year, edition, pages
2014. 47-54 p.
Displacement ventilation, Unsteady CFD, URANS, Air, Air quality, Computational fluid dynamics, Indoor air pollution, Inlet flow, Perforated plates, Turbulence, Mean flow gradients, Turbulence intensity, Unsteady cfd simulations, Unsteady simulations, Velocity profiles, Ventilation
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:hig:diva-19218ScopusID: 2-s2.0-84924672267OAI: oai:DiVA.org:hig-19218DiVA: diva2:806148
13th International Conference on Indoor Air Quality and Climate, Indoor Air 2014, 7-12 July 2014, Hong Kong