Submitted by Maria.Kapsalaki on Mon, 10/28/2013 - 11:12
A model tunnel (approximately ten hydraulic diameters) with different designs of the tunnel mouth has been placed in a wind tunnel and has been subjected to the effects of external wind by varying the wind direction at the mouth of the tunnel. In the experimental oriented study pressures have been measured and the airflow has been made visible with smoke and by the sand erosion method (semolina). The relation between the flow ratio and the direction of the wind has been explored.
This document describes the designing process of a smoke management system for an atrium, using tools going from empirical equations to complex models, in order to have a safe evacuation of occupants in case of fire.
To validate the emergency operation modes of a 7 km long underground railway tunnel ventilation system, a full-scale experimental investigation has been performed. The results of the test showed that the tunnel ventilation system can successfully provide the critical air velocity necessary for a fire sized 13.6 MW. Alternatively, the large reservoir for smoke under the tunnel ceiling may give more time for escape and ought to be considered when planning for the emergency procedure. The system is now operating commercially.
In modern buildings, smoke control systems are integrated into the air supply systems. It is possible that the design of the smoke control system will dominate the design process of the air supply system. Smoke reservoir size is one of the design parameters for the smoke control system. The reservoir size has been limited to 2000-3000 m2 in both Hong Kong and UK. However, this study revealed that the smoke reservoir size should be considered in connection with the slab ceiling height of the smoke zone. The higher the slab ceiling, the larger the smoke reservoir could be.
Many buildings under construction or renovation today require a smoke-control system, either to gain building regulations approval or, to protect the building, its contents and occupants, and to offer assurance of business continuity in case of fire. Traditionally natural rather than powered smoke ventilation systems have been preferred. The article considers why this has been the case, and covers failsafe operation, self compensating, quiet operation and cost effectiveness.