Aluminum-propane-air hybrid flames in a Hele-Shaw cell

This paper introduces a novel Hele-Shaw cell apparatus to be used for the study of propagation and stability phenomena in heterogeneous flames. In particular, the apparatus is used to experimentally examine the coupling/decoupling of dual-front flames propagating in suspensions of micron-size aluminum particles in propane-air gas mixtures at varying gas equivalence ratios and aluminum concentrations. The results show that the thermal coupling that exists between the primary propane-air flame front and the secondary aluminum flame front is a strong function of the rate of reaction, and of the temperature, of the secondary front and much less dependent on the reaction rate or temperature of the primary front. It is also shown that flame instabilities in hybrid aluminum-propane-air flames significantly increase the flame surface area, enhance the propagation rate, and can also exhibit complex interactions with front coupling. ? 2020 The Combustion Institute. Published by Elsevier Inc. All rights reserved.