Experimental study on turbulent expanding flames of lean hydrogen/air mixtures

The aim of this paper is to report new experimental results on the effect of turbulence on the combustion properties of lean to stoichiometric H-2/air mixtures in a closed, fan-stirred, spherical vessel. To do so, a new experimental setup, spherical bomb, has been used to investigate the effect of a given and well-characterized turbulence intensity on the increase of hydrogen/air flame speed and on the combustion pressure. The initial hydrogen molar percent of H-2 in air was comprised between 16% and 28%. The initial turbulence created in the vessel prior to ignition was varied between 0.56 and 2.81 m/s for an integral length scale of around 50 mm. It was shown that the turbulent speed increases drastically when the turbulence is increased but the maximum combustion pressure remains the same. A correlation was proposed in order to the turbulent speed. The proposed turbulent flame speed correlation was able to predict not only the present data but also the results of the literature (Kitagawa et al., 2008). (C) 2016 by The Combustion Institute. Published by Elsevier Inc.