Unusual Flame Gases

Abstract

Hydrogen–air mixtures containing less than about 20 per cent hydrogen when burnt at an orifice undergo two highly contrasted modes of combustion which result in flame gases of very different types. In our experiments well-mixed mixtures of hydrogen and air contained in a tank were supplied to a burner in the form of a long narrow slit, the width of which was 1/16 in. The temperatures attained by very fine platinum – rhodium wires (0.0005 in. diameter) and by quartz-covered platinum wires (0.0005 in. overall diameter) were measured at some two hundred points in the flame gases. A contour map of the platinum wire temperatures in the lower portion of the flame gases resulting from the combustion of a 14 per cent mixture is shown in Fig. 1. These results are summarized in Fig. 2 and extended to a flame height twice that shown in Fig. 1. The temperatures measured by the quartz wire were almost exactly the same as those measured by the platinum wire, except in the early stages after combustion at the sides of the combustion zone (see dotted curves, Fig. 2).