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Atomization and Sprays

Journal of the International Institutes for Liquid Atomization and Spray Systems

ISSN for PRINT: 1045-5110

Institutional price:	$787.00
Issues per year:	8

Best Paper Award Selection - Editorial Board Site

1991, Volume1

112 pages

Issue price - $75.00

ANALYSIS OF PRE-IGNITION MECHANISMS IN A DIESEL COMBUSTION ENGINE WITH THE AID OF IMAGE PROCESSING

Antonio Cavaliere
Dipartimento di Ingegneria Chimica, Università Federico II, Naples, Italy

S. Pintus
Dipartimento di Ingegneria Chimica, Chimica Industriale e Scienza dei Materiali, Universitá di Pisa, Pisa, Italy

Leonardo Tognotti
Dipartimento di Ingegneria Chimica, Chimica Industriale e Scienza dei Materiali, Universitá di Pisa, Via Diotisalvi 2, 56100 Pisa, Italy

S. Zanelli
Dipartimento di Ingegneria Chimica, Chimica Industriale e Scienza dei Materiali, Universitá di Pisa, Pisa, Italy

ABSTRACT

Simple image processing procedures have been applied to assist the study of unsteady diesel sprays, which represents one of the most difficult two-phase flow configurations to analyze by means of a nonintrusive method such as optical diagnostics. The first problem considered is rejection of the background for easier pattern recognition, or for automatic analysis of the image, which can be required for further elaboration. Simple image elaboration procedures are shown in order to assess the possibility of obtaining clean, “purged” images, which carry information only about the investigated area. The second problem considered is the restitution of images on linear scales, so that they can be analyzed by means of false-color representation. This operation is useful mainly when the range of gray levels in the image is compressed, i.e., in those cases for which the human visual system fails to detect repeatable, slight, spatially resolved, gray-level variations. The procedures are used in the analysis of a set of pictures, obtained at different crank angles in a diesel engine, from which some peculiar pre-ignition mechanisms can be inferred. The analysis of the spray evolution demonstrates the relevance of wall impingement. Considerations of mechanisms of ignition and flame propagation are also reported.