Maximum temperature of thermal plume beneath an unconfined ceiling with different inclination angles induced by rectangular fire sources

Highlights: • Experiments are carried out to measure the maximum temperature of inclined ceiling jet. • The maximum temperature increase along with the increasing of ceiling inclination angle. • The maximum temperature is proportional to that of free thermal plumes at ceiling level. • A new global correlation for the maximum temperature of weak impinging flow is established. - Abstract: The maximum temperature of thermal plume beneath an unconfined ceiling with different inclination angles induced by rectangular fire sources were investigated experimentally and theoretically. The experimental results show that the maximum temperature rise at the ceiling level with different ceiling inclination angles is proportional to that of a free fire thermal plume; and the maximum temperature rise increases according to the ceiling inclination angle when other experiment conditions remain unchanged for a given fire source; A new global non-dimensional correlation combined the effects of source-ceiling height, heat release rate, source aspect ratio and especially the ceiling inclination angle are proposed to predict the maximum temperature rise. The new proposed correlation can predict the maximum temperature rise beneath the ceiling induced by axisymmetric, rectangular and line fire sources uniformly. This work provides supplementary results over previous knowledge of temperature distribution beneath the inclined ceilings. It can also provide guidance for thermal risk assessment and fire safety design of open-styled spaces.