Fires in Ducts: A review of the early research which underpins modern tunnel fire safety engineering

Much of the early research which now underpins tunnel fire safety design was carried out experimentally, using small scale ducts. This paper reviews such experiments, mostly carried out in the 1960s, 1970s, and 1980s, highlighting the assumptions and limitations of the early studies, which may have been forgotten as the equations developed have been applied in practice in the subsequent years. The review covers three primary topics; fire propagation under 'turbulent slug flow' conditions, stratification & flame spread, and backlayering & critical ventilation velocity.