TY - JOUR
T1 - Pulsating instability in the nonadiabatic heterogeneous SHS flame
T2 - Theory and experimental comparisons
AU - Makino, Atsushi
AU - Law, Chung King
N1 - Funding Information:
AM and CKL were respectively supported by the Grant-in-Aid for Scientific Research of the Ministry of Education, Japan, and the US NASA Microgravity Program. We thank Dr. S. B. Margolis for his interests and helpful suggestions during the course of this investigation.
PY - 1996
Y1 - 1996
N2 - 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.
AB - 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.
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U2 - 10.1016/S0082-0784(96)80008-7
DO - 10.1016/S0082-0784(96)80008-7
M3 - Article
AN - SCOPUS:0030354272
SN - 0082-0784
VL - 26
SP - 1867
EP - 1874
JO - Symposium (International) on Combustion
JF - Symposium (International) on Combustion
IS - 2
ER -