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7.4. COMPARISON WITH EXPERIMENTAL RESULTS 219
It is also impossible here to estimate which fraction of the intensity given by (7.28)
will actually turn into turbulence in each case.
7.4 Comparison with experimental results
As aforesaid the available experimental evidence is not sufficient to establish either
one of the proposed theories in a definite way precluding the others. We owe the most
complete set of experiments to Bollinger and Williams [2] and to Wohl and Shores [7]
referred to herein. Some of the results obtained show laws of variation of u t which
approach those predicted by Karlovitz and by Scurlock and Grover. However, their
effects appear which are either not predicted by theory or in contradiction with it. An
example of effects not predicted is the influence of the mixture’s composition, since
it is verified that the effect of turbulence is not the same for rich mixtures than for
poor ones, even when operating under identical conditions and with the same laminar
propagation velocity. This is especially true for certain combustibles (like butane) and
this fact cannot be explained with any of the proposed theories. Wohl believes this
effect to be due to the different laminar stability in poor and rich mixtures. An example
of effects appearing in contradiction with theory is the influence of the scale of
turbulence, which after Scurlock’s predictions, should be considerable and which according
to experimental results is very small. Consequently it is necessary to increase
experimental evidence before final decision may be reached.
References
[1] Mallard, F. and Le Chatelier, H.: Ann. de Mines. Vol. 8, Sev. 4, 1884, p. 274.
[2] Damköhler, G.: The Effect of Turbulence on the Flame Velocity in Gas Mixtures.
NACA Tech. Mem. No. 1112, 1947.
[3] Bollinger L. M. and Williams, D. T.: Effect of Reynolds Number in the Turbulent-
Flow Range on Flame Speeds of Bunsen-Burner Flames. NACA Tech. Note
No. 1707, Sept. 1948.
[4] Scurlock, A. C.: Flame Stabilization and Propagation in High Velocity Gas
Streams. Meteor Report No. 19, July 1948.
[5] Williams, G. C., Hottel, H. C. and Scurlock, A. C.: Flame Stabilization and
Propagation in High Velocity Gas Streams. Third Symposium (International)
on Combustion, Williams and Wilkins Co., Baltimore, 1949, pp. 21-40.
[6] Karlovitz, B. Denniston, D. W. and Wells, F. E.: Investigation of Turbulent
Flames. Journal of Chemical Physics, Vol. 19, No. 5, May 1951.