EFFECT OF COMBUSTOR DIAMETER ON NATURAL GAS COMBUSTION CHARACTERISTICS

Abstract

This paper represents a numerical study on the effect of combustor diameter on natural gas combustion characteristics. The numerical simulation of a non-premixed natural gas flame has been performed in a three dimensional combustor model. CFD studies were carried out using ANSYS FLUENT 14.5 code. The effect of changing the combustor diameter is studied under different operating conditions of air swirl numbers and excess air factors where two swirlers with S = 0.5 and 1.5 are used at λ = 2 and 4 at constant natural gas fuel mass flow rate of 0.4 g/s. The obtained results from the simulations are presented to clarify the effect of the studied geometrical parameter on combustion characteristics such as axial velocity distribution, reverse flow zone (RFZ), flow pathlines, vortex eye location, recirculated flow mass ratio, temperature distribution and concentration percentage of combustion products. The results show that the length of the central reverse flow zone (CRFZ) increased by increasing combustor diameter in addition to increasing the recirculated flow mass ratio while the average outlet temperatures and the average concentrations of CO and unburnt CH4 at combustor outlet are decreased.