New Perspectives on the Critical Velocity for Smoke Control

Published: 19 April, 2010

This paper presents new analytical solutions for the critical velocity for smoke control in tunnels and cross-passages. These analytical solutions for the critical velocity dispense with the need to solve for two coupled non-linear equations, and avoid the drawbacks associated with iterative approaches to solving for such equations. The paper also discusses the use of the critical velocity concept in road, rail and metro tunnels, both as a design objective and also as a target for emergency operations. It concludes that there are significant drawbacks in the generation of tunnel air velocities in excess of the critical velocity, due to the increased risks of fire growth and the destruction of any smoke stratification. The importance of tunnel ventilation control in emergency scenarios is therefore emphasised.

File: 420-427_New Perspectives.pdf (872k)

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