Comparison of results from large-scale and small-scale tunnel experiments

Abstract

A series of 1:20 small-scale tunnel experiments have been carried out as a scaled down representation of a previously undertaken large-scale heavy goods vehicle (HGV) cargo load tunnel fire experiment. The small-scale tunnel has dimensions of 0.365 m (W) × 0.260 m (H) × 11.9 m (L) and a maximum forced ventilation velocity of 0.68 m/s is adopted corresponding to the velocity of 3 m/s used at large-scale. A gas burner and cribs constructed of medium density fireboard (MDF) have been used as the fuel sources with temperatures, heat release rate (HRR) and velocity data recorded in the small-scale tunnel experiments. A scaled down HRR curve derived from the large-scale experiment was reproduced by the gas burner. Temperatures in the small-scale gas burner experiment can effectively represent those at large-scale during the fire growth and decay stages although measurements at the fully developed stage are lower than the results from the large-scale tunnel experiment. In the small-scale tunnel experiments using the cribs time delays are applied to correct the recorded data in order to obtain the instantaneous HRR. Temperature profile comparisons between the small-scale crib and large-scale HGV cargo load experiments are not applicable since the HRR curves from the crib experiments only approximately reproduce the large-scale HRR profile.