Scaling the interaction of water sprays and flames

Scaling relations for (dry) compartment fires have been extended to include interactions of water sprays with the gas phase, including flames. All important interactions scale properly, except attenuation of thermal radiation by the sprays. Methods of scaling spray devices to meet requirements are discussed, including application of geometrically similar spray nozzles and, where geometric similarity cannot be assured, the application of an effective spray nozzle diameter. Extinction experiments were conducted in a large space on linear scales differing by a factor of ten, where freeburn heat release rates varied from 1.1 to 1530 kW. The results are well correlated in normalized coordinates based on the scaling theory. There is no evidence, in the extinction scenario investigated, of the improper scaling of thermal radiation attenuation, or a slight inaccuracy in the scaling of mean drop diameter to requirements.