A visual study on turnabout phenomenon of vortex roll-up in forced jet diffusion flames
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An experimental study on the effect of forcing amplitude in forced jet diffusion flames has been conducted. Various flow visualization techniques are employed using optical schemes, including light scattering photography, high speed imaging by motion analysis, and determination of velocity vector and vorticity fields from PIV data. Particular attenttion is focused on the turnabout mechanism around the elongated flame, which has not been reported previously, and on the inner coherent structure of the forced jet in the attached flame regime. In particular, we present a schematic diagram that aids in the understanding of the turnabout mechanism of vortex roll-up. This diagram explains why the forced flame is elongated under moderate forcing amplitudes but shortens again when the forcing amplitude is further increased.
KeywordsCoherent structure behavior Elongated flame Fluctuating velocity Forced jet flame Forcing amplitude In-burning flame Phase synchronization Turnout of vortex roll-up
- L. G. Pearson, A. Gabelli, I. G. Shepherd and N. B. Hamilton, Structure in diffusion flames an accoustic viewpoint, Joint International Conference Australia/ New Zealand and Japanese Section of the Combustion Institute, Sydney, (1989) 24.Google Scholar
- K. M. Lee, S. K. Oh and J. Park, A visual investigation of coherent structure behavior under toneexcited laminar non-premixed jet flame,J. of KSME B. 27 (2003) 275.Google Scholar
- S. G. Kim, K. T. Kim and J. Park, An experimental study on the lift-off behavior of tone-excited propane non-premixed jet flames,J. of KSME B. 28 (2004) 569.Google Scholar
- S. K. Oh, An experimental study on the structure of forced jet and jet diffusion flames, Ph. D. Thesis, KAIST, Taejeon, (2001).Google Scholar