This paper reports on the measurement and analysis of time resolved thermal radiation from combustion of methane, ethane, and propane clouds formed from laboratory scale vapor samples initially contained within a soap bubble. The time scale of the radiant heat pulse was found to be the same as that of the fluid mechanical motion (Fay and Lewis, 1976). The time-integrated radiant energy flux, expressed as a fraction of the initial fuel heating value, was between 0.09 and 0.15 for these fuels, with some dependence on initial fuel volume. The radiation was correlated by a grey gas model, which assumed a uniform time-dependent temperature in a spherical cloud and a time-independent absorption coefficient. The grey gas temperature decreased monotonically during and after the period of combustion. The absorption coefficient was found to be a function of the initial fuel volume and fuel type; it was between 10#x2212;3and 10#x2212;2cm#x2212;1and decreased slightly with increasing initial fuel volume.
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