DOI: 10.1615/TSFP4
AN EXPERIMENTAL APPROACH TO VORTEX-FLAME INTERACTION IN KARMAN VORTEX STREETS BEHIND A ROD-ARRAY
RESUMO
Structure and behavior of the spark-ignited propane-air pre-mixed flames established in the quasi-turbulent and quiescent wake, which is generated by quickly moving a fine rod-array vertically downward in the quiescent stoichiometric propane-air mixture, are observed and analyzed using the tomography and PTV method. It is found that the quasi-turbulent and quiescent wake proposed here is composed of Karman vortex streets with the characteristic length scale ranging 0.2~ 0.5 mm and the tangential velocity of 4.0 m/s, and that it satisfies rather small and intense turbulence conditions of ld/δL ~ 1 and νθ/SL ~ 10. Since the interface between the unburnt and burnt gases exhibits complicated and rugged appearances and consists of a continuous series of wrinkled laminar flame elements having the length scale ranging 0.2 ~ 2 mm, the turbulent flame initiated in the quasi-turbulent and quiescent wake with the moderately intense turbulence conditions of ld/δL ~ 1 and νθ/SL ~ 10 is classified into the finely wrinkled laminar flame.