Linear pulsating instability of the nonadiabatic heterogeneous self-propagating, high-temperature synthesis (SHS) flame is analyzed based on a premixed mode of propagation for the bulk flame supported by the non-premixed reaction of dispersed nonmetals in the liquid metal. The formulation allows for volumetric heat loss in the bulk flame and temperature-sensitive Arhenius mass diffusion in the liquid with infinitely fast surface reaction in the diffusion limit, as is the case for most SHS processes. Neutral stability boundary, which separates the regime of steady combustion from that of pulsating combustion, has been obtained by determining the critical heat-loss parameter as functions of the eldovich number, melting parameter, and melting point of the metal Results show that the instability is promoted by increasing the heat generation rate at the bulk flame and/or reducing the heat-transfer rate from the flame, particularly by increasing the mixture ratio, decreasing the degree of dilution, decreasing the size of the nonmetal particles, increasing the compact diameter, and decreasing the thermometric conductivity of the compacted mixture. The theoretical results are found to agree well with available experimental data, in trend and in approximate magnitude, indicating that the heterogeneous theory for the SHS flame propagation captures the essential features of this unstable SHS combustion process.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Fuel Technology
- Energy Engineering and Power Technology
- Mechanical Engineering
- Physical and Theoretical Chemistry
- Fluid Flow and Transfer Processes