Keywords: bluff-body slot burner, dynamic motion, flame effect, fuel effect, gaseous fuel, recirculating flow, transition, vortex structure, heat transfer, diffusion combustion, flow visualisation
Vortex structure and heat transfer in a diffusion combustion field with circulating flow
A numerical study was performed to examine the vortical structures for combusting flow from a two-dimensional bluff-body slot burner in the transitional recirculating flow. The numerical results support the flow visualisation results for C3H8 combustion by Chin and Tankin [Chin, L.P. and Tankin, R.S. (1991) 'Vortical structures in a 2-d vertical bluff-body burner', Combustion Science and Technology, Vol. 80, pp.207?229]. We identify the fuel effect on the dynamic vortical structures inside the flame for C3H8 and CH4 fuels. The Reynolds number for the inner slot fuel flow is varied from 10?250 at a fixed Reynolds number of 400 for the outer slot air flow. As a result of the study on a two-dimensional bluff-body burner, it was possible to reproduce the dynamic motions of vortical structures obtained by Chin and Tankin visualisation experiment. In the low Reynolds number region, vortex structures in the recirculating region gives large effect in the flame form. In addition, it was confirmed that independently of the fuel variety, the flow at the bluff-body aft comes into three shape varieties.