Effect of thermo-hydrodynamic instability on structure and characteristics of filtration combustion wave of solid fuel

Abstract

Numerical modelling of flame front stability for the inverse wave (with trailing combustion front) of filtration combustion of solid fuel is performed. The problem is treated in terms of dimensionless variables and parameters. It is found that propagation of a plane combustion front becomes unstable under certain conditions. In this case the front spontaneously inclines. The thermo-hydrodynamic mechanism is supposed to be responsible for instability developing. Anisotropic effective mass diffusivity (dispersion) is also taken into account. It turns out that anisotropic diffusivity affects structure and conversion distribution of the inclined combustion front. It is shown that the key parameters determining stability of combustion wave are dimensionless gas flow rate and width of reactor. The range of these parameters corresponding to the stable plane front is determined. It is shown that stability occurs either for small reactor widths (dimensionless values <1), or low gas flow rate (below 0.2). The optimised values of considered dimensionless parameters for maximal productivity are determined.

Keywords:

• filtration combustion
• combustion instability
• thermo-hydrodynamic mechanism
• permeability
• dispersion

Disclosure statement

The authors have no financial interest in the results of this research project.

Supplemental data

Supplemental data for this article can be accessed here. Animation 1 Evolution of filtration combustion front (H = 16, no dispersion)

Notes

1. The inverse structure of the co-flow filtration-combustion wave is where initial fuel is heated to the combustion temperature whereas the burned part of porous layer is quenched by inlet gas flow to its initial temperature.

Additional information

Funding

This work was supported by the Belarusian Republican Foundation for Fundamental Research [grant number T14P-127]; Russian Foundation for Basic Research [grant number 14-03-90033].