Influence of Strouhal number on pulsating methane–air coflow jet diffusion flames

Sánchez-Sanz, Mario and Bennett, B.A.V. and Smoke, Mitchel D. and Liñán Martínez, Amable (2010). Influence of Strouhal number on pulsating methane–air coflow jet diffusion flames. "Combustion Theory and Modelling", v. 14 (n. 3); pp. 453-478. ISSN 1364-7830. https://doi.org/10.1080/13647830.2010.490048.

Description

Title: Influence of Strouhal number on pulsating methane–air coflow jet diffusion flames
Author/s:
  • Sánchez-Sanz, Mario
  • Bennett, B.A.V.
  • Smoke, Mitchel D.
  • Liñán Martínez, Amable
Item Type: Article
Título de Revista/Publicación: Combustion Theory and Modelling
Date: 2010
ISSN: 1364-7830
Volume: 14
Subjects:
Faculty: E.T.S.I. Aeronáuticos (UPM)
Department: Motopropulsión y Termofluidodinámica [hasta 2014]
Creative Commons Licenses: Recognition - No derivative works - Non commercial

Full text

[img]
Preview
PDF - Requires a PDF viewer, such as GSview, Xpdf or Adobe Acrobat Reader
Download (4MB) | Preview

Abstract

Four periodically time-varying methane–air laminar coflow jet diffusion flames, each forced by pulsating the fuel jet's exit velocity Uj sinusoidally with a different modulation frequency wj and with a 50% amplitude variation, have been computed. Combustion of methane has been modeled by using a chemical mechanism with 15 species and 42 reactions, and the solution of the unsteady Navier–Stokes equations has been obtained numerically by using a modified vorticity-velocity formulation in the limit of low Mach number. The effect of wj on temperature and chemistry has been studied in detail. Three different regimes are found depending on the flame's Strouhal number S=awj/Uj, with a denoting the fuel jet radius. For small Strouhal number (S=0.1), the modulation introduces a perturbation that travels very far downstream, and certain variables oscillate at the frequency imposed by the fuel jet modulation. As the Strouhal number grows, the nondimensional frequency approaches the natural frequency of oscillation of the flickering flame (S≃0.2). A coupling with the pulsation frequency enhances the effect of the imposed modulation and a vigorous pinch-off is observed for S=0.25 and S=0.5. Larger values of S confine the oscillation to the jet's near-exit region, and the effects of the pulsation are reduced to small wiggles in the temperature and concentration values. Temperature and species mass fractions change appreciably near the jet centerline, where variations of over 2% for the temperature and 15% and 40% for the CO and OH mass fractions, respectively, are found. Transverse to the jet movement, however, the variations almost disappear at radial distances on the order of the fuel jet radius, indicating a fast damping of the oscillation in the spanwise direction.

More information

Item ID: 32410
DC Identifier: http://oa.upm.es/32410/
OAI Identifier: oai:oa.upm.es:32410
DOI: 10.1080/13647830.2010.490048
Official URL: http://www.tandfonline.com/doi/abs/10.1080/13647830.2010.490048#.VET_4U8cQdV
Deposited by: Biblioteca ETSI Aeronauticos
Deposited on: 30 Oct 2014 13:19
Last Modified: 30 Oct 2014 13:19
  • Logo InvestigaM (UPM)
  • Logo GEOUP4
  • Logo Open Access
  • Open Access
  • Logo Sherpa/Romeo
    Check whether the anglo-saxon journal in which you have published an article allows you to also publish it under open access.
  • Logo Dulcinea
    Check whether the spanish journal in which you have published an article allows you to also publish it under open access.
  • Logo de Recolecta
  • Logo del Observatorio I+D+i UPM
  • Logo de OpenCourseWare UPM