Wrinkled premixed flame

Aldredge, R. C., and F. A. Williams. 1991. Influence of wrinkled premixed-flame dynamics on large-scale, low-intensity turbulent flow. J. Fluid Mechanics 228 487-511. 

To analy2e premixed turbulent flames theoretically, two processes should be considered (/) the effects of combustion on the turbulence, and (2) the effects of turbulence on the average chemical reaction rates. In a turbulent flame, the peak time-averaged reaction rate can be orders of magnitude smaller than the corresponding rates in a laminar flame. The reason for this is the existence of turbulence-induced fluctuations in composition, temperature, density, and heat release rate within the flame, which are caused by large eddy stmctures and wrinkled laminar flame fronts. 

Thomas, A., The development of wrinkled turbulent premixed flames, Combustion and Flame, 65,291-312,1986. 

Considering the case of premixed flames, it is noted by Thomas and Williams [26] that sound radiation can be related to the rate of change of the flame surface area by assuming that the burning velocity is constant. Similarly, Ref. [35] and later Ref. [36] indicate that in the wrinkled flame regime, the rate of chemical conversion is directly linked to the flame surface area A(t). For a mixture of fresh reactants at a constant equivalence ratio, the pressure field is directly linked to the instantaneous flame surface ... 

This recent attempt differs from the previous classification where the wrinkled flamelet regime has been considered up to rj = (5l- Chen and Bilger have proposed to tentatively classify the different turbulent premixed flame structures they observed among four different regimes ... 

FIGURE 10.8. Schematic illustration of the relationship between the turbulent flame speed and the wrinkled flame area for a premixed turbulent flame consisting of a wrinkled laminar flame. 

Premixed flames may be influenced by the Darrieus-Landau hydrodynamic instability [1, 2] when the chemical heat release is sufficiently large. Hydrodynam-ically unstable premixed flames are not always observed, however, because of stabilizing influences of buoyancy and thermal diffusion. The long-wavelength flame-surface wrinkles are attenuated by buoyancy for downward propagating flames, and thermal-diffusive effects stabilize small-wavelength wrinkles when the... 

G. Searby and P. Clavin. Weakly turbulent wrinkled flames in premixed gases. Combustion Science and Technology, 46 167-193, 1986. 

Premixed turbulent combustion regime diagram proposed by Chen and Bilger. Two intermediate regimes are delineated between distributed flame front and wrinkled laminar flamelets. (Reprinted from Chen, Y.C. and Bilger, R., Combust. Flame, 131, 400, 2002. With permission. Figure 9, p. 411, copyright Elsevier editions.)... 

Mantel, T. and R. Borghi (1994). A new model of premixed wrinkled flame propagation based on a scalar dissipation equation. Combustion and Flame 96,443 157. 

For spray combustion in diesel engines and gas turbines, the flame types for premixed and non-premixed combustion fall mainly into the wrinkled and stretched flame regime in region (3), and into the distributed or perturbed flames in region (4). 

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