Numerical research of premixed combustion of diluted methane in a tubular flame burner

This paper presents numerical simulations of premixed combustion of low calorific value gases (LCVGs), providing a description of the flame characteristics in a tubular flame burner. The investigated gaseous fuels were methane diluted with nitrogen, simulating LCVGs with different heat values by regulating quantity of nitrogen. The flame shape and thermal field are consistent with experimental results. It consists of two segments of different feature, the lengths of which dependent on inlet velocity. Comparative study of flow fields at cold and thermal states were carried out with an aim to gain further understanding of the flow/flame interaction in the tubular burner. Heat release from combustion diverts the main pressure gradient to axial direction, thereby tangential velocity drop tends to close with axis of swirling, and axial velocity distribution changes to be trapezoid-shaped. Changing in low heat values influences the burning positively, while the flow does not exert an apparent effect.