Filtration combustion

Solutions to models with different length scales may contain regions such as shocks, steep fronts and other near discontinuities. Adaptive meshing strategies, in which a spatial mesh network is adjusted dynamically so as to capture the local behavior accurately, will be described. The algorithm will be tested on an example of filtration combustion. 

The algorithm described above was successfully used for simulation of the filtration combustion process for the synthesis of nitrogen ceramics. 

We will first discuss some results obtained for a onedimensional formulation of the filtration combustion process. The initial conditions are given by... 

VHiereas the previous case revealed temperature and conversion profiles propagating with almost constant velocity ("constant-pattern profiles"), the next case shows oscillatory behavior of the filtration combustion process for parameters a = 1.0, p = 0.08, y = 0.05, 6 = 1.0, (A) = 100.0, L =50.0 and 8 = -10.0. Figure 3a... 

One-dimensional simulations provide useful information about the filtration combustion system such as values for propagation velocity under various conditions and an indication of the mode of... 

In contrast with the theory for gasless reactions (Sections IV,A and IV,B). which was adapted from classical combustion theory, filtration combustion (FC) theory was developed specifically to describe gas-solid reactions in CS (Merzhanov eta/., 1972 Aldushin ef a/., 1974). 

Fig. 27. Different types of filtration combustion (one-dimensional schemes).

A model of filtration combustion in a thin porous layer, immersed in a bath of gaseous reactant, has also been investigated (Shkadinskii et al, 1992a). In this case, only filtration of gas from the surroundings to the sample, normal to the direction of combustion propagation (cross-flow filtration), should be considered. New pulsating instabilities associated with the gas-solid chemical reaction and mass transfer of gas to the porous medium were identified. 

More recently, the cross-flow filtration combustion configuration (Fig. 29), commonly used for powder production, was investigated (Dandekar et al., 1990). Within the reactor, a rectangular container holds the solid reactant powder, and the gaseous reactant is transported from the surroundings to the front not only by longitudinal flow from above, but also by countercurrent flow from ahead of the front. The assumptions used in the model were as follows ... 

The interaction of gasless and filtration combustion has also been examined (Aldushin et al., 1994b). The competition between simultaneous gasless and gas-solid reactions... 

Aldushin, A. P., New results in the theory of filtration combustion. Combust. Flame, 94,308 (1993). 

Aldushin, A. P., Filtration combustion of metals. In Thermal Wave Propagation in Heterogeneous Media (Russ.). Nauka, Novosibirsk, 1988, p. 52. 

Aldushin, A. R, Merzhanov, A. G., and Sepliarskii, B. S., Theory of filtration combustion of metals. Combust. Explos. Shock Waves, 12,285 (1976b). 

Dandekar, H. W., Puszynski, J. A., and Hlavacek, V, TWo-dimensional numerical study of cross-flow filtration combustion. AlChE J., 36,1649 (1990). 

Ivleva, T. I., and Shkadinskii, K. G., Mathematical modeling of two-dimensional problems in filtration combustion of condensed systems. Proceedings of the Kinetics and Mechanisms of Physicochemical Processes, Chernogolovka, Russia, 74 (1981). 

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