Combustion in micro-channels with a controlled temperature gradient

• A new experimental device was developed to study combustion in micro-channels.
• An original heating method ensures uniform radial temperature distribution.
• Flame dynamics were studied for wide range of equivalence ratio (0.5–1.5).
• The different flame regimes were confirmed and oscillating flames were observed.
• A detailed characterization of the FREI regime was conducted.

In recent years many studies were undertaken in the field of micro-combustion, experimentally and numerically. In the present work, a new experimental device was developed. It consists of a micro tubular channel with an external heating provided by three hydrogen/oxygen flames positioned at the downstream side of the tube. This system ensures a uniform heating inside the channel. As described in previous studies, three distinct flame behaviors were observed: stable flames at high flow velocity, flames with repetitive extinction and ignition (FREI) in the middle flow range, and weak flames, at low flow velocity. This experimental study on the combustion of methane/air mixtures in a microchannel was undertaken to provide detailed information on flame behavior over a wide range of equivalence ratios (0.5–1.5) and flow velocities. Finally, a detailed analysis on the flame instabilities was performed. The results show a good agreement with several numerical results, and the study on FREI frequencies reveals a particular trend of instability with the change of the experimental conditions.