OCR Text |
Show Droplet size is determined from the visibility of the Doppler burst where the visibility is determined as: v = !MAX - *MIN *MAX + *MIN where IMAX and IMI[yJ are as shown in Figure 1. Based on scalar diffraction theory, the relationship between particle size and visibility can be written as: 2 J, (TT D/6) V = i u D/6 where: D = particle diameter 6 = 2 sin 0/2 = interference fringe spacing This relationship, shown in Figure 2, is monotonic up to a D/6 value of about 1.0 and gives a maximum measurement range of about 10:1. Subsequent to Farmer's work, several authors (2)(3)(4) showed the sensitivities of the visibility technique to the collection optics criteria and recommendations established in these studies were followed in the present investigation. Application of PSI to CWS Sprays During the course of coal-water combustion studies, it was found that for some combinations of fuel and air mass flow ratios, atomization of the slurry was poor. As a result, a large fraction of the slurry mass failed to burn and was either deposited on the combustor floor or carried up the stack as unburned coal. This observation indicated a radical change in the number of large particles with atomization conditions. Since the capabilities of the PSI technique only extend |