Abstr:Tunnel fire
Application Area 4: Civil Construction & HVAC
Application Challenge AC4-04
Abstract
The Memorial Tunnel Fire Ventilation Test Programme consists of a series of full-scale fire tests carried out in a disused road tunnel in West Virginia in the United States from September 1993 to March 1995. The purpose of the tests was to establish the effectiveness of various forms of emergency ventilation in controlling smoke spread in the tunnel for different fire sizes. The results are summarized in an extensive database which can be used for validation purposes as well as design guidance.
A number of different ventilation arrangements were considered including fully transverse, partially transverse, longitudinal and natural. For this application challenge the longitudinal test 615B has been selected.
Over the last 10 years, CFD has become a standard tool for assessing the effectiveness of emergency ventilation for smoke control in situations where standard prescriptive codes alone may not be applicable. This includes complex buildings, e.g. those with atria, underground stations and road/rail tunnels. At the same time, a number of high-profile incidents, with tragic results, such as the fires at King’s Cross underground station in London and in the Mont Blanc road tunnel have underlined the dangers of uncontrolled fire and smoke spread in enclosed spaces.
The increasing reliance on CFD predictions of fire and smoke spread in these circumstances means that validation of these predictions becomes increasingly important. The Memorial Tunnel fire tests represent an almost unique source of fully-scale, semi-realistic data on fire and smoke spread in a road tunnel and as such present a very pertinent application challenge for CFD in the Civil Construction and HVAC sector.
The design or assessment parameters (DOAPs) relevant in this case are:
- Mass flow rate of air through tunnel
- Volume flow rate at different locations
- Critical velocity (at which back-layering of smoke in controlled)
- Time-varying velocity distributions
- Time-varying temperature distributions
- Time-varying carbon monoxide distributions
Contributors: Nicholas Waterson - Mott MacDonald Ltd