Flow pattern in ventilated rooms with large depth and width.

In many buildings, for instance tunnels, underground, parking areas and industrial halls, the L/H is so large that the flow pattern induced by a two dimensional supply air jet along the ceiling can be completely different from that in rooms of normal sizes. Earlier model experiments indicate that, in this case, the supply jet will have a limited penetration length (Ire) because the entrainment generates a backward flow in the lower part of the ventilated space which at a given distance will disperse or deflect the jet. In this study both model experiments and Computational Fluid Dynamics (CFD) are employed to study the isothermal flow pattern in a ventilated room with different L/H and inlet velocities. The maximum size of the model is 1.4* 0.72*0.0714m and the measurement is made with a Laser Doppler anemometer. The CFD simulation is carried out by Flovent code with a k-e model. Although some discrepancies occur it is clear that the simulation correctly represents the general features of the measurements. Both measurements and CFD simulations show the tendency that lre/H may be independent of Will when W/H >5. The velocity decay of the wall jet and the maximum velocity in occupied area are also studied in this paper.