- Author
- Veldman, C. C. | Kubota, T. | Zukoski, E. E.
- Title
- Experimental Investigation of the Heat Transfer from a Buoyant Gas Plume to a Horizontal Ceiling. Part 1. Unobstructed Ceiling. Quarterly Progress. March 1975-June 1975.
- Coporate
- California Inst. of Tech., Pasadena
- Sponsor
- National Bureau of Standards, Gaithersburg, MD
- Report
- NBS GCR 77-97, 1975, 115 p.
- Distribution
- Available from National Technical Information Service
- Contract
- GRANT-59004
- Keywords
- buoyant plumes | ceilings | compartment fires | fire plumes | heat transfer | room fires | scale models
- Abstract
- This report presents an experimental investigation of the axisymmetric heat transfer from a small cable fire and resulting buoyant plume to a horizontal, unobstructed ceiling during the initial states of development. A propane-air burner yielding a heat source strength between 1.0 kW and 1.6 kW was used to simulate the fire, and measurements proved that this heat source did satisfactorily represent a source of buoyancy only. The ceiling consisted of a 1/16" steel plate of 0.91 m diameter, insulated on the upper side. The ceiling height was adjustable between 0.5 m and 0.91 m. Temperature measurements were carried out in the plume, ceiling jet, and on the ceiling. Heat transfer data were obtained by using the transient method and applying corrections for the radial conduction along the ceiling and losses through the insulation material. The ceiling heat transfer coefficient was based on the adiabatic ceiling jet temperature (recovery temperature) reached after a long time. A parameter involving the source strength Q and ceiling hight H was found to correlate measurements of this temperature and its radial variation. A similar parameter for estimating the ceiling heat transfer coefficient was confirmed by the experimental results. This investigation therefore provides reasonable estimates for the heat transfer from a buoyant gas plume to a ceiling in the axisymmetric case, for the stagnation region where such heat transfer is a maximum and for the ceiling jet region (r/H 0.7). A comparison with data from experiments which involved larger heat sources indicates that the predicted scaling of temperatures and heat transfer rates for larger scale fires is adequate.