Abstract
The characteristics and extinction of the partially-premixed diffusion flame are studied both experimentally adopting counter-flow burner system and theoretically using matched asymptotic expansion techniques. Results show that the partially-premixed diffusion flame exists at high rate of strain when the degree of partial premixing is low. The results for the practical partially premixed diffusion system indicate that the partially premixed diffusion flame plays an important role in charaterizing the turbulent flames.
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Abbreviations
- B :
-
Frequency factor
- c :
-
1−|γ|
- c p :
-
Specific heat
- D :
-
Nozzle diameter
- D i :
-
Mass diffusivity of i-th species
- D a :
-
Damkohler number (Bσ/k)
- E a :
-
Activation energy
- k :
-
Thermal conductivity
- L :
-
Nozzle distance
- Le i :
-
Lewis number(k/ϱc p D i )
- m :
-
Heat loss factor
- Q :
-
Heat of combustion per unit mass of fuel consumed
- R :
-
Universal gas constant
- T :
-
Nondimensional temperature
- T a :
-
Activation temperature(E a /R)
- T ad :
-
Adiabatic flame temperature
- V :
-
Nozzle exit velocity
- Y :
-
Mass fraction
- y r :
-
Y op /ε p L e o
- γ:
-
Heat loss parameter for diffusion flame
- δ 0 :
-
Reduced Damkohler number for diffusion flame
- ε:
-
Small parameter(T 2 f /T a )
- ζ:
-
Inner stretched coordinate
- η:
-
Similarity variable
- θ:
-
Perturbed temperature
- χ:
-
Flame stretch
- χ:
-
Partial premixing parameter
- ξ:
-
Inner stretched coordinate
- ρ:
-
Density
- σ:
-
Stoichiometric oxidizer to fuel mass ratio
- φ 1,φ 2 :
-
Defined in Eq.(1)
- ω:
-
Reaction rate
- d :
-
Diffusion flame
- E :
-
Extinction
- F :
-
Fuel
- f :
-
Flame
- i :
-
Species(i=O, F)
- m :
-
Partially-premixed diffusion flame
- N :
-
Nitrogen
- O :
-
Oxidizer
- p :
-
Premixed flame
- ±∞:
-
Boundaries
References
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Im, H.G., Chung, S.H. On the characteristics of partially-premixed diffusion flame in a strained flow field. KSME Journal 3, 139–145 (1989). https://doi.org/10.1007/BF02953599
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DOI: https://doi.org/10.1007/BF02953599