Turbulent Behaviour in a Low Aspect Ratio Dump Combustor at Low Swirl Number

This paper reports an experimental investigation of a non-reacting flow in a low aspect ratio dump combustor with taper exit. The separated flow reattachment length for this combustor was higher than the length of the combustor. In order to understand the flow behavior inside the combustor, the velocity measurement inside the combustor was carried out by calibrated one-dimensional hot wire probes for the same flow conditions. The turbulent intensity variation inside the combustor without swirl flow was found to be axi-symmetric. The turbulence intensity along the centre line is lower than at other radial locations because of the presence of the potential core. The intensity in the core region increases as one moves along the centerline in the axial direction, which can be attributed to the weakening of the potential core and the increase in the extent of the shear layer. The turbulence behavior significantly changed with the use of a swirler at the inlet of the combustor. The intensity variation inside the combustor is more uniform than the low swirl number SN = 0.23. The higher turbulence kinetic energy and turbulent dissipation rate was observed at this swirl number. Therefore, the effect of swirl is expected to improve the combustion through better mixing and flame stabilization.