Influence of turbulent flow characteristics on flame behaviour in diffuser combustors

Abstract

The influence of turbulence on flame location in a diffuser-type combustor is the focus of this study. Two types of diffuser combustors were selected to study the influence of turbulence intensity and length scale on flame location. The first combustor was a cylindrical diffuser, and the second combustor had a conical insert. As turbulence intensity and length scale determine Taylor-scale Reynolds numbers, this parametric study also explored the effects of the latter. Flame moved towards the inlet of the diffuser with the increase in turbulence intensity and length scale in cases with and without a conical insert. At a high turbulent length scale, the flame rapidly dropped at the inlet of the diffuser with a conical insert as the turbulence intensity increased. By contrast, the flame dropped to an intermediate level for the diffuser without a conical insert. Results showed that the Taylor-scale Reynolds number is a parameter that influences flame location, as well as turbulence intensity and length scale. An increase in the Taylor-scale Reynolds number leads to the movement of flame location towards the combustor inlet. Flame drops to the inlet of the combustor at a high turbulent Taylor-scale Reynolds number.