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Journal of Visualization

, Volume 3, Issue 1, pp 37–50 | Cite as

Interferometric visualization of jet flames

  • Stella A. 
  • Guj G. 
  • Mataloni A. 
Article

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.

Keywords

interferometry jet flames combustion destabilization coherent structures 

Nomenclature

D

burner diameter

F

concentration of fuel

g

modulus of gravity acceleration

Gr

Grashof number

K

Gladstone Dale coefficient

l

aspect ratio of the burner

L

length of the burner pipe

n

index of refraction

O

concentration of oxygen

p

pressure

r

radial co-ordinate of cylindrical frame of reference

Re

Reynolds number

Ri

Richardson number

S

burning velocity

T

temperature

u

local flow velocity component normal to the flame front

V

velocity

x,y,z

Cartesian co-ordinate system

Greek symbols

Δ

variation

ε

angle of divergence of the Wollaston prism

ϕ

equivalence ratio

ϕ

phase of the electromagnetic wave associated with laser ray

λ

wavelength of the laser source

μ

viscosity

ν

kinematic viscosity

ρ

density

ζ

optical path

ω

vorticity

Subscripts

ad

adiabatic

b

burnt gas state

bar

baroclinic

J

jet

L

laminar

st

stoichiometric

TIP

flame tip

u

unburnt gas state

ambient or reference condition

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Copyright information

© The Visualization Society of Japan 2000

Authors and Affiliations

  • Stella A. 
    • 1
  • Guj G. 
    • 2
  • Mataloni A. 
    • 2
  1. 1.Dip. Meccanica e AeronauticaUniversità Di Roma “La Sapienza”RomeItaly
  2. 2.Dip. Ingegneria Meccanica e IndustrialeUniversità Di Roma TreRomeItaly

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