Three-Dimensional Mass Fraction Distribution of a Spray Measured by X-Ray Computed Tomography

Abstract

In order to design a spraying system with the desired characteristics, the atomization process has to be understood in detail, including the primary breakup of the liquid core. Accurate prediction of primary breakup is a major barrier to computer-based analysis of spray combustion. The development oj^ models is hindered by the lack of validation data in a region where the fluid is dense, and optical access is therefore limited. The present experimental study is aimed at probing the spray structure by means of X-ray computed tomography (CT). A full-cone atomizer (0.79 mm oriflce diameter) spraying in air at ambient pressure is investigated as a proof of concept. A mixture of water and iodine is used as the working fluid, providing elevated X-ray absorption and therefore, improved signal-to-noise ratio. Several hundreds of X-ray projections are acquired as the spraying atomizer is rotated in front of the detector. Standard software for medical imaging is used to reconstruct the three-dimensional time-averaged distribution of liquid mass fraction in the full fleld of view, from the intact liquid core to the dilute spray region. A spatial resolution of 0.6 mm is obtained along the spraying direction, while the resolution is 0.3 mm in the other two directions. Significant asymmetries in the structure of the spray are revealed.

Numerical and experimental investigation of early stage diesel sprays

“…Steady and unsteady liquid jet flows and their breakup remain an ongoing field of investigation [1][2][3][4][5][6][7][8].…”

“…For the development of diesel engines with both optimal fuel economy and minimum pollutant emissions, it is necessary to comprehend the spray processes and then characterize the effects of different parameters and engine operating condition on fuel flow structures. This is a challenging subject to study, both experimentally and numerically [4,15,18,31,32]. In this study, the flow inside the nozzle and the liquid bulk near the nozzle exit and its fragmentation (primary atomization) are investigated.…”

“…In this study, the flow inside the nozzle and the liquid bulk near the nozzle exit and its fragmentation (primary atomization) are investigated. 4 This paper concentrates on the effect of in-nozzle turbulence. The effects of cavitation will be studied in future work.…”

Characterization of scalar mixing in dense gaseous jets using X-ray computed tomography

“…These devices were fundamentally designed to image internal structures through an optically opaque outer shell, and similar systems have already been successfully utilized to measure mean flow structures in the context of fuel sprays and multiphase flows (Chaouki et al 1997;Coletti et al 2014;Escudero and Heindel 2014;Linne 2013). The recent work of Heindel (2011) provides a detailed overview of applications of X-ray diagnostics to multiphase flows, with a substantial emphasis on tomographic methods.…”

Quantitative imaging of single-shot liquid distributions in sprays using broadband flash x-ray radiography

“…Void fraction measurements made at kHz-rates were shown by (Char et al, 1990;Woodward et al, 1995). Time-averaged three-dimensional data by (Meyer et al, 2008;Meyer et al, 2010: Balewski et al, 2010Eichner, 2013;Coletti et al, 2014;Marchitto et al, 2015) were collected. Multiple sources were employed to make time-resolved tomographic measurements by (Lim et al, 2013).…”