Experiments and Numerical Simulations of Vertical Flame Spread on Charring Materials at Different Ambient Temperatures

A new experimental apparatus for measuring flame spread rates at different ambient temperatures is presented. The 2 m long sample is pre-heated with air to the desired temperature, ignited from below with a small propane burner, and flame spread is monitored with thermocouples at the surface of the sample. The rate of vertical concurrent flame spread as a function of ambient temperature is determined on cylindrical Birch rod samples and on polyvinylchloride cable samples. Corresponding flame spread scenarios are numerically simulated using an axi-symmetric solution of the flow field and a pyrolysis model with parameters estimated from thermogravimetric and cone calorimeter experiments. The simulation model was able to predict the flame spread rates within the uncertainties associated with the experiments and postsimulation analysis of the spread rate.