Fire Safety Science Digital Archive

Many theoretically and/or experimentally derived correlations have been proposed for predicting the temperature rise, velocity and optical smoke concentration at given radial positions in the ceiling jet that is generated by both a steady and time-dependent fire and flowed under the flat and horizontal ceiling. Some previous studies have also reported on the ceiling jet flow generated by a steady fire below an inclined smooth ceiling. This study especially focuses on the ceiling jet that is generated from a comparatively large fire source, namely flame touching the ceiling, with varying ceiling inclination angle of up to 40°. An experimental approach was employed to clarify the effect of inclination angle of a smooth ceiling. Temperature and velocity distributions in ceiling jet were measured in detail using thermocouple rake and PIV system. Velocity was also measured bi-directional flow probe. Based on these data, the decrease in temperature rise and velocity along the steepest run in the upward direction, horizontal distribution of temperature in the spanwise direction and the Gaussian momentum and thermal thickness were discussed. Empirical formulae for these parameters are presented.