The use of two simplified models was demonstrated in this study, the box and momentum methods, in order to simulate complex diffusers in room airflow modelling by CFD. Additional flow information is needed by the two methods, which is not available from product catalogues of diffuser manufacturers - the information required includes the distribution of discharge air velocity, box size and flow direction. A test method was developed on how to obtain the additional information with minimal effort under ASHRAE standard 70-1991.
Presents CFD simulations and field experiments on ventilation efficiency in an underground car park with natural ventilation. A series of experiments were carried out to validate the results of the CFD calculation, looking at the decay of the concentration of tracer gas (SF6) in the area studied. A long/linear analysis of concentration with time was used to deduce the air change rate. It was found that experimental data were in good agreement with the CFD simulation result.
The application of Computational Fluid Dynamics (CFD) for ventilation research and design of ventilation systems has increased during the recent years. This paper provides an investigation of direct description of boundary conditions for a complex inlet diffuser and a heated surface. A series of full-scale experiments in a room ventilated by the mixing principle have been performed for validation of the models. The experimental results include measurements of temperature as well as measurements of velocity and turbulence by Laser Doppler Anemometry (LDA).
Results of a CFD simulation of the wind-assisted stack ventilation of a single-storey enclosure with high and low-level ventilation openings are presented and compared with both the laboratory measurements and the analytical model of the flow and thermal stratification developed by Hunt and Linden (2001). Comparisons show that close quantitative agreement is obtained between the thermal stratification predicted by the CFD and the analytical model and experimental measurements.
The results of numerical simulation on the effects of solar chimney for ventilation in the new building of Faculty of International Environmental Engineering Kitakyushu University, Japan are described. The air velocity and pressure within the solar chimney were estimated by simplified methods and CFD calculation and both results agreed quite well. It was found that the air flow rates would depend on the inside wall temperatures and section ratio of solar chimney with the same section area.
Describes a simplified numerical model, POMA (Pressurized zOnal Model with Air-diffuser, intended to predict the airflow pattern and thermal distributions within a room. The authors introduced jet characteristic equations into the model to make its application general for mechanically ventilated buildings. The models prediction was compared with experimental results and with that of another zonal model and a CFD model. Both natural and forced ventilation were considered. States that the findings show that the POMA model is a practical tool for ventilation system design.
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