Experimental study of the combustion dynamics of jet fuel droplets with additives in the absence of convection

Comprehensive study of initial diameter effects and other observations on convection-free droplet combustion in the standard atmosphere for n-heptane, n-octane, and n-decane

“…The results confirm earlier conclusions [17,29] that the burning rates of the freely floating and fiber mounted droplets were close to each other. On the other hand, the fiber support perturbed the soot structure and promoted aggregates to stick to the fiber during the burning process [49] .…”

“…Though the burning rate is predicted to be constant and independent of time and droplet size, experiments show that the burning rate decreases as the initial droplet diameter increases and that it depends on time [3,13,14,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] . This trend has not been fully explained, owing in part to the inability to model all of the important processes in droplet burning (i.e., unsteady transport, variable properties, soot formation, radiation, complex combustion chemistry).…”

Automated Data Analysis for Consecutive Images From Droplet Combustion Experiments

“…As a base case for comparison we used the package Image-Pro Plus v.6.3 as our prior droplet burning studies (Bae and Avedisian, 2004;2009;Liu and Avedisian, 2012) employed this package for image analysis. A typical procedure for manually obtaining droplet diameter measurements includes the following steps: (1) the droplet image is loaded into the software; (2) a threshold value of grayscale intensity is selected to convert the original grayscale image (with intensity values ranging from 0 to 255) into a black and white (black = 0, white = 255) binary image; (3) an elliptical "area of interest" (AOI) tool is activated and the AOI is manually placed on what is perceived to be the droplet boundary based on the assigned threshold value; (4) the pixel readings for the width W and height H of the elliptical AOI are recorded; (5) the effective droplet diameter, in units of pixels, is calculated by taking a geometric average of the width and height of the ellipse (i.e., D = (W×H) 0.5 ); and (6) the process is repeated for each frame in the sequence.…”

“…Only then can a two-dimensional description of the droplet and its flame provide sufficient information to determine their shape and size. This assumption is valid when gas phase spherical symmetry prevails, as is achieved by removing all forms of convection around the droplet, which is accomplished by burning "small" droplets in a low gravity environment (Dietrich et al, 1996;Avedisian, 2000;Bae and Avedisian, 2004;Hicks et al, 2010). Fig.…”

Observation of droplet behavior of emulsified fuel in secondary atomization in flame

“…Because of the interest in puffing and micro-explosion, many researchers have studied these using single droplet experiments (Segawa, et al, 2000;Watanabe, et al, 2009;Watanabe, et al, 2010;Suzuki, et al, 2011;Mura, et al, 2014;Califano, © 2014 The Japan Society of Mechanical Engineers [DOI: 10.1299/jtst.2014jtst0009] et al, 2014). The fiber-support technique, used to anchor the droplet (Segawa, et al, 2000;Bae and Avedisian, 2004;Yozgatligil, et al, 2007;Watanabe, et al, 2009;Watanabe, et al, 2010;Suzuki, et al, 2011;Mura, et al, 2014;Califano, et al, 2014), has been used in studies of secondary atomization because it provides considerably useful information regarding, for example, clear droplet behavior. Because nucleation on the surface of the wire used in the fiber-support technique is unavoidable, some researchers have used unsupported techniques (Warnat, et al, 1994;Jackson and Avedisian, 1998;Mikami, et al, 1998).…”