Flame brush thickness

If the turbulent flame is ever proven to have asymptotically a constant flame brush thickness and constant speed in constant, i.e., nondecaying, turbulence, then the aforementioned turbulent flame speed and the flame brush thickness (5 give a well-defined sufficient characterization of the flame in its asymptotic behavior. However, it is not proven up to now that the studied experimental devices have been large enough to ensure that this asymptotic state can be reached. Besides, the correct definitions for the turbulent flame speed or flame brush thickness, as given above, are far from... 

Temporal evolution of the flame brush thickness for the previously described mixtures of hydrogen, methane, and propane with air. (Reproduced from Renou, B. and Boukhalfa, M., Combust. Set. Technol., 162, 342 2001. With permission. Figure 2, p. 353, copyright Gordon Breach Science Publishers (Taylor and Francis editions).)... 

In this instance, the flame is produced by a line of sparks located in a square cross-section combustion chamber equipped with quartz windows after it has been filled through a perforated plate. Figure 7.1.3a shows the image obtained by the direct shadowgraphy the light crosses the entire 10 cm wide vessel and both the apparent thickness of the flame and the turbulent flame brush can thus be directly estimated. 

The most suitable wires for this purpose are pure lead, indium and gold. The Pb and In wires should be between 0.1 and 0.4 mm thick, the Au ca. 0.05 to 0.1 mm. Under presure, these metals are deformed plastically and adapt themselves to the contour of the joint. There will momentarily be the greatest pressure at the point at which the ends cross over and thus the greatest deformation will occur there until a uniform thickness is attained. If such a joint resists dismantling, it can usually be freed by heating it gently with a brush flame or hot air gun. 

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