Measurement and Prediction of Infrared Radiation Extinction by Water Sprays
J F. Widmann
The optical extinction of infrared radiation by a water spray has been investigated both experimentally and theoretically. A theoretical analysis based upon Mie theory for spatially inhomogeneous, polydisperse droplet ensembles was used to predict the extinction of radiation propagating through the spray. The analysis resulted in extinction values over the range of wavelengths from 1 micrometers to 10 micrometers, which constitutes an important range for radiative heat transfer calculations in fires. Phase Doppler interferometry was used to measure the droplet size distributions and spatial variation of droplet number density within the spray. The predictions were validated with transmission measurements obtained as a function of wavelength and position using a blackbody as a radiation source and an infrared spectrograph as the detector.
International Journal of Heat and Mass Transfer
fire dynamics, Mie theory, phase Doppler interferometry, radiation extinction, thermal attenuation, water droplets, water sprays