Quenched limits

To examine the details of the structure of flames in channels under quenching conditions, numerical methods were used. Two-dimensional CFD simulation of a propane flame approaching a channel between parallel plates was carried out using the FLUENT code [25]. The model reproduced the geometry of the real channels investigated experimentally. Close to the quenching limit, the burning velocity, dead space, and radius of curvature of the flames were all close to the experimental values. [Pg.107]

The fact that the quenching limits of upward propagating rich limit flames are much wider in comparison with those moving downward can be explained in terms of preferential diffusion. When the molecular diffusivity of the deficient reactant is higher than the thermal diffusivity of the mixture and when the flame is stretched (upward propagating convex flames... [Pg.108]

Jarosinski, J., Podfilipski, J., and Fodemski, T., Properties of flames propagating in propane-air mixtures near flammability and quenching limits. Combust. Sci. Tech., 174 167, 2002. [Pg.110]

The line shifts of f-f transitions discussed in sect. 4.2, offer an interesting possibility to establish high pressure gauges. As mentioned in sect. 2, ruby is still the most widely used gauge for pressure determination. However, some deficiencies caused a continuous search for improved sensor materials. Especially the temperature induced broadening and quenching limits the application of ruby to below 500 °C. [Pg.552]

However, not only the contact lines themselves are beneath all the points but their slope is also too small to explain the true concentration dependence. Perhaps these difficulties stimulated Stevens to propose the original finite-sink approximation instead of the existing theory [103,250]. The inconsistency of this model is seen from the very fact that it does not discriminate between the Stem-Volmer and the steady-state constants, k and k = lim, >rXj k(t), and ascribes to the latter the concentration dependence, which is not inherent to k in principle. At the same time the model predicts the linear dependence of the results in coordinates 1/k versus c1/3, and this linearity was confirmed experimentally a number of times [6,248,250,251], According to their finite-sink model [248], the straight lines representing this dependence for different temperatures should intersect at a common point where the static quenching limit is unambiguously located. ... [Pg.362]

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