Experimental study of thermo-acoustic instabilities in a backward-facing step stabilized methane premixed flame in high turbulence flow

摘要

Afterburners, ramjets, lean prevaporised premixed combustion sys-tems, as well as many power devices exhibit undesirable combustion instabilities under certain operating conditions. Combustion instabilities involve complex processes of gas flow, heat release and acoustic feed-back. The present study focuses on the flow field characterisation of highly turbulent premixed flames typical of industrial gas turbines. Low-frequency combustion instabilities are studied experimentally in a lean premixed model combustor of rectangular cross section. The ONERA/ LAERTE combustion facility consists of a 1.7 m long inlet duct (section of 100x65 mm~2) and of a 1.4 m long dump combustor (rearward-facing step) of 100x100 mm~2 section. The premixed methane flame