Experimental Studies On Flashover Phenomenon In Retail Shop Fire Of Terminal Hall And Smoke Control In Atrium Fire

What this thesis tries to solve are: when fires occur in retail shops of the terminal halls, flashover happens or not and what's kind of effect it will have on the smoke movement in the whole building; whether the current code about the exhaust smoke design of the atrium are reasonable or not and how to amend and make them comply with the needs in practical projects.This thesis adopts the method which combines model experiment with computer numerical calculations and studies the smoke flow in terminal halls and atria and the affecting factors. It mainly includes the following aspects and arrives at corresponding conclusions: An experimental reduced-scale compartment, which is based on a 1/8-scale model developed by the PolyU/USTC, is established. The experiments are carried out on the conditions of flashover and its influence on the big halls during the retail shop fires. The results indicate that flashover occurs easily in small rooms; In case flashover occurs, the small room becomes a big thermal source and the produced smoke volume will then increase greatly and the smoke layer descends rapidly in the big hall.The field model for smoke flow has been established. The experiment adopts the model of the fire flue gas turbulence flow under the action of the buoyancy and the fire area is taken as a volumetric heat source. It applies the program PHOENICS to the numerical experiments. Then the numerical results are compared with that of the model experiments, verifying that the program is applicable. The numerical results about the fires in different shaped atria indicate that, according to the standard smoke exhaust system designed by the current code, thin-tall atria cannot usually obtain an ideal result; while the cubic or oblate atrium can generally and the atria whose volume exceeds 17000 m3 (except thin-tall atria ) can.The numerical results about the fires in thin-tall atria indicate that there exists a hot-air layer at the top commonly when fires happen; the layer will reduce the efficiency of the smoke exhaust system; when the quantity of smoke exhaust is augmented to at least 1.3 times prescribed in the standard of the existing code, the smoke exhaust system can get fine result; only adding exhaust outlets can raise the smoke layer, but not obviously; if both the quantity of smoke exhaust and the number of exhaust outlets are increased simultaneously, the efficiency of the smoke exhaust system becomes much more ideal, and it is advisable to place the added outlets on the plane of 2/3 height of the atria above the ground level.