Development of a hydrogen-air flame in a vertical channel with a horizontal diaphragm

The paper describes an experimental study of lean hydrogen-air flames in a 1490-mm-long closed vertical channel of a square 138×138 mm section behind a horizontal diaphragm with a diameter of 50 mm. Schlieren images of the flame in a homogeneous hydrogen-air mixture are given along with the pressure dynamics for the mixtures with 6, 8, and 16 vol.% of hydrogen. It is shown that shear instability behind the diaphragm leads to a local instability of the lateral surface of a lean hydrogen-air flame, which causes a short-wave perturbation that spreads over the flame surface and crumples it, thereby enhancing the combustion.