Paper Conference

Proceedings of BauSim Conference 2020: 8th Conference of IBPSA-Germany and Austria

     

COMPARISON OF STATIONARY AND TRANSIENT RANS MODELLING TO PREDICT THE SPATIAL VELOCITY FIELD OF A CEILING INTEGRATED FAN

O. Glahn, T. Voß, K. Voss, S. Schwickert

DOI: https://doi.org/10.3217/978-3-85125-786-1-11
Abstract: Ceiling fans allow an increase of the local air velocity on the human body. The associated heat transfer increases user’s temperature tolerance in warm environments. In the presented study, the differences in the application statistical turbulence models (RANS) for modelling the air flow induced by a ceiling integrated fan is outlined with particular focus on comparing steady and transient simulations. Results of a CFD simulation (Fluent) are shown and compared with measured data of the horizontal velocity distribution. The study shows that especially the transient simulation using the Realizable k-ε model follows the flow pattern described in literature. But at 1.1 m above the floor, the mean absolute error in the center of the jet is at least five times larger than the measurement uncertainty and 41 % higher than the measured values. The stationary model using the Multiple Reference Frame (MRF) approach instead, shows the smallest mean absolute error, exceeding the measured values in the center of the jet by 16%. But in the immediate vicinity of the fan an unrealistic velocity distribution can be observed, if the moving zone needs to be small due to obstacles. For a freely suspended ceiling fan, the moving zone can be adjusted accordingly and the flow pattern can be improved. But modelling a ceiling integrated fan with a fan housing and obstacles in the near region, transient simulations using rigid body motion are required for accurate results.
Pages: 104 - 111
Paper:
bausim2020_11