Measurement and characterization of fully transient diesel fuel jet processes in an optical engine with production injectors

Evolving one-dimensional transient jet modeling by integrating jet breakup physics

“…The resultant jet-tip penetration as a function of time was compared to recently acquired optical measurements. 14 The model results and associated experimental data are shown in Figure 3.…”

“…6,44 Several mathematical profiles were tested for the increase in overall jet boundary and subsequent decrease in liquid core diameter and compared to the experimental results of jet penetration from the literature. 14 As explained in that paper, a modified Otsu 45 statistical technique was employed to determine the jet boundary from the optical images. The jet penetration is determined at the head of the jet, the point of the image that has the highest contrast ratio with the background of the entire jet (as compared to the sides).…”

“…6 Having to slightly tune the final dispersion angle from measured values to match experimental penetration data has been accepted in the literature 48 for these simplified models, especially since the uncertainty in optically determined dispersion angles is much higher than that for determining penetration distances. This is due to the steep gradient in signal at the leading edge of the jet as opposed to a gradual decrease in signal seen on the sides of the jet when using optical techniques such as Schlieren and shadowgraphy, as evident in images from Kostas et al 7 The final spreading angle used in the model had to be modified from the measured results; 14 larger spreading angles were needed in the model to match the penetration results from the data. A similar modification was built into the correlations by Hiroyasu and Naber 23,36 as the tuning constant 'a', and commented on by the developers and users of the Sandia 1-D model.…”

“…13 This paper details the development of a new 1-D modeling approach to transient jets aimed at more accurately representing the physical processes observed in recently acquired optical measurements of transient jets. 14 The focus of this work is on the accelerating transient associated with the ramp-up period of the injection process. The ramp-up period is of significant importance for combustion performance and emissions as it determines the initial mixing rates and penetration of the jet which impact the ignition process and potential interaction of the jet with the piston bowl.…”

Macroscopic and microscopic characterization of non-reacting diesel sprays at low and very high injection pressures

“…The diesel spray formation includes complex and heterogeneous processes, including high-velocity jet flow, liquid droplet break-up, atomization, and evaporation of a dense liquid spray in a turbulent flow environment. To ensure a good mixture between the air and the fuel, the spray must penetrate into the combustion chamber and atomize [71,120,126,160,197,222]. The small temporal and spatial scales resulted from these processes makes the study of the diesel spray evolution a complicated problem.…”