Affiliations: Dip. Meccanica e Aeronautica, Università Di
Roma "La Sapienza," Via Eudossiana 18, 00184 Rome, Italy | Dip. Ingegneria Meccanica e Industriale,
Università Di Roma Tre, Via Della Vasca Navale 79, 00146 Rome,
Italy
Abstract: This paper presents visualizations of reacting, round jets of the
premixed and nonpremixed type realized by using interferometry and,
complementarily, direct photography. The available interferometer, proposed by
Carlomagno (1986), employs low-cost components and is flexible and robust to
geometrical misalignments, allowing the drawbacks limiting the application of
traditional interferometric systems to be overcome. Several flames are produced
by varying the non-dimensional, governing parameters (Reynolds number,
equivalence ratio, Grashof number). The results discussion is organized
considering laminar, transitional and turbulent flows. In the steady, laminar
case, in view of the radial symmetry of the fringes pattern, the temperature
field is reconstructed by the interferograms. The structure of the transitional
and turbulent combusting jets, primarily determined by shear layer
destabilization mechanisms and large-scale vortices formation due to buoyancy,
is analyzed and differences with isothermal flows are pointed out. In turbulent
regime, studied only for premixed combustion case, qualitative insights into
the structure of the reaction zone as a function of the equivalence ratio and
turbulence properties in the incoming fresh mixture are also deduced.
