Ray-tracing analysis of shadowgraph and diffuse back-illumination extinction imaging of a synthetic GDI spray

Lazzaro, Maurizio

doi:10.1007/s00348-021-03325-1

Cited by 1 publication

(1 citation statement)

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“…Previously cited research in this field, however, is largely based on diffuse back illumination (DBI) configurations, without giving due consideration to the lighting geometry. In fact, apart from the intrinsic inaccuracy of the method (Lazzaro 2021), the DBI can be assimilated to a cone beam configuration (just swap sensor and source) and, in this case, the approximate FDK algorithm should be applied (Feldkamp et al 1984;Hsieh et al 2013) to analytically backproject the extinction data, acquired in the appropriate angular interval. However, the very large size of the "source", far from being point-like, would heavily influence the results and inevitably very blurred and unfaithful images of the spray would be obtained.…”

Section: Introductionmentioning

confidence: 99%

Shadowgraph Tomography of a High Pressure GDI Spray

Lazzaro,

Alfuso,

Ianniello

2024

Preprint

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An isooctane spray from a high-pressure multi-hole GDI injector (Bosch HDEV6) was characterized by means of optical extinction tomography, relying on parallel illumination by a focused-shadowgraph setup. The tests were carried out in air at ambient conditions at an injection pressure of 300 bar. Extinction images of the spray were acquired over a 180-degree angular range in 1-degree increments. The critical issues of optical extinction tomography of sprays, related to the strong light extinction by the dense liquid core of fuel jets, were addressed. To mitigate artifacts arising from the reconstruction process, the extinction data were subjected to spatially-variant filtering steps of both the raw and post-log data, before being analytically inverted through the inverse Radon transform. This made it possible to process extinction data for very large optical depths. A nearly complete three-dimensional reconstruction of the spray was obtained, providing significant details of the spray morphology and the internal structure of the jets throughout the spray development. The different phases of the atomization process from the near-field to far-field regions of the spray were observed.

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Section: Introductionmentioning

confidence: 99%