On the morphological analysis of CH2-H2-air flame instability (Contributo in atti di convegno)

Type
Label
  • On the morphological analysis of CH2-H2-air flame instability (Contributo in atti di convegno) (literal)
Anno
  • 2012-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.4405/35proci2012.VII7 (literal)
Alternative label
  • V.Moccia, J.D'Alessio (2012)
    On the morphological analysis of CH2-H2-air flame instability
    in XXXV Meeting of the Italian Section of the Combustion Institute, Milano, Italy, 10-12 Ottobre, 2012
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • V.Moccia, J.D'Alessio (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#pagineTotali
  • 6 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • Istituto Motori - C.N.R. (literal)
Titolo
  • On the morphological analysis of CH2-H2-air flame instability (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#isbn
  • 978-88-88104-14-0 (literal)
Abstract
  • The paper deals with the assessment of the stability characteristics of gas flames, through the analysis of their morphology. The activity has been carried out in the DHARMA laboratory of Istituto Motori - C.N.R., where the burning properties of combustible gases are investigated in conditions representative of i.c. engines and gas turbines. The experimental approach is based on the analysis of spherical expanding flames, in a high-pressure, constant-volume vessel. The flame growth is recorded with a high-speed, high-resolution shadowgraph system. The results have been obtained with mixtures of CH4, H2 and air, varying the initial pressure from 3 to 18 bar, and the amount of H2 in the mixture from 0 to 30%. Initial temperature was 293÷305 K and equivalence ratio ?=1.0. The explored range of operating conditions allowed to evaluate the relative weight and mutual interaction of two key parameters: the starting pressure and the H2 percentage. As well documented in literature, the tendency of a flame to become unstable can be inferred from the so-called \"stretch analysis\", which, along with the laminar burning properties, delivers the Markstein length. The latter is a measure of flame stability. Evidence of instability, if any, eventually shows up as a series of morphological alterations of the smooth laminar surface, namely large cracks, followed by cellular structures. The appearance of these perturbations on the flame surface can be associated with two characteristic times, allowing the definition of two corresponding dimensions. Aim of the paper is to evaluate these critical radii as an effective marker of flame instability, as compared to the Markstein length. (literal)
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