Air assisted atomization and spray density characterization of ethanol and a range of biodiesels

► PDA and microscopic imaging have been used to assess the atomization characteristics of different biodiesels and ethanol. ► Two image processing techniques are suggested to characterize sprays with a large proportion of deformed droplets. ► The biodiesels are more difficult to atomize, however, the majority of break-up for all liquids occurs by x/D = 5. ► An increase in Weber number results in a reduction in the probability of long and short ligaments appearing.