Ventilation flow analysis - flow visualisation and LDA measurements in water scale models, validation of numerical results.

Within the frame of the IEA Annex 20, laboratory and numerical experiments were conducted in order to study the flow within an isothermal parallepipedic testroom (L x W x H = 4.2 m x 3.6 m x 2.5 m). The air is injected through a complex diffuser (made of 84 nozzles) near the ceiling and is evacuated through a rectangular exit just below the inlet. While other participants to the Annex 20 made measurements on aeraulic testrooms, we used a hydraulic model scaled to the sixth. The parameters were determined according to a Reynolds similitude. For the experimental approach both Laser Doppler Anemometry and flow visualizations were used. Numerical simulations were carried out using the EOL- 3d software developed at INRS. A comparison between experimental results and numerical predictions is presented. Symmetry, air diffuser modelling and low Reynolds number effects are discussed from both numerical and experimental point of views. The numerical predictions are in good agreement with the experimental results.