A Method Based on Dimensional Analysis to Estimate the Quasi‐Steady‐State Fire Heat Release Rate in a Compartment With Ceiling Vent

ABSTRACT Compartments with ceiling vents find application in commercial buildings, ship cabins and nuclear facilities. Fire development in such compartments is characterised by the accumulation of hot gases at the ceiling level. Flow through the vent is complex in nature, wherein the effects of both buoyancy and pressure‐driven flow become important. In the present work, a set of dimensionless groups is developed by the systematic application of the Buckingham Pi theorem for analysing quasi‐steady‐state fire in a ceiling‐vented compartment. The dimensionless groups are then used to develop a procedure for estimating heat release rate (HRR) and heat losses through the compartment boundaries and vent. A sample calculation is presented to show the application of the dimensionless groups. It is shown that heat losses through the compartment boundaries can be estimated without explicit knowledge of the convection and radiation heat transfer coefficients. The overall heat transfer coefficient for heat flow through the solid boundaries of the compartment is obtained as part of the calculation procedure. The estimated HRRs are compared with CFD predictions for heptane and ethanol pool fires in compartments of volume 0.75 and 17 m 3 having ceiling vents of different sizes. The results are found to agree within ±20%.