Empirical and Analytical Correlations of Droplet Properties

Atomization, or generally speaking droplet generation, is an extremely complex process that cannot yet be precisely predicted theoretically. The lack of general theoretical treatment of droplet processes has led to the development of numerous empirical correlations for droplet properties as a function of process parameters and material properties. In this chapter, empirical and analytical correlations for the prediction of droplet properties, such as droplet size distribution and droplet deformation characteristics will be summarized from experimental observations and theoretical analyses in available literature. 

Droplet generation is typically a random process. Droplet sizes are usually characterized by a wide spectrum. In many 

However, a monodisperse spray seldom exists in reality and is difficult to produce, although it can be defined mathematically as a spray consisting of droplets of the same size. Hence, a monodisperse spray usually refers to a spray in which droplets are very narrowly distributed. However, it is merely a relative term since a droplet size distribution that is sufficiently narrow in one application may be 

As AD is made smaller, a histogram becomes a frequency distribution curve (Fig. 4.1) that may be used to characterize droplet size distribution if samples are sufficiently large. In addition to the frequency plot, a cumulative distribution plot has also been used to represent droplet size distribution. In this graphical representation (Fig. 4.2), a percentage of the total number, total surface area, total volume, or total mass of droplets below a given size is plotted vs. droplet size. Therefore, it is essentially a plot of the integral of the frequency curve. 

Mathematical representation of droplet size distribution has been developed to describe entire droplet size distribution based on limited samples of droplet size measurements. This can overcome some drawbacks associated with the graphical representation and make the comparison and correlation of experimental results easier. A number of mathematical functions and empirical equations1423 427 for droplet size distributions have been proposed on the basis of 

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