Numerical Modeling of an Axisymmetric Trapped Vortex Combustor

Abstract

This paper is concerned with the numerical study of the effect of injection momentum on the flow field, fuel-air distribution and temperature distribution within the cavity of an axisymmetric trapped vortex combustor (TVC) under reacting flow condition. Shear Stress Transport (SST) k-ω model was used for turbulence modeling while combustion was simulated using the Eddy Dissipation Model (EDM). The predicted velocity field and temperature profile inside the cavity matched reasonably well with the experimental results available in literature. Reacting flow studies revealed that when the cavity momentum flux ratio, MFR_c ≤ 1, the TVC exhibited similar flow features, irrespective of the relative momentum between the cavity and the mainstream flow. For these cases, a single vortex, rotating in the stream-wise was established within the cavity. The temperature distribution was also found to be similar within the cavity for these cases. However, nonuniform fuel air distribution was observed for these cases. In contrast, MFR_c > 1 cases exhibited entirely different flow pattern. For these cases, multiple vortices were observed within the cavity, with a counter streamwise vortex oriented at the bottom wall. Within this counter streamwise vortex, the temperature distribution was observed to be uniform. Hence, MFR_c is the dictating factor in determining the flow and temperature field within the TVC cavity. Beside this, by maintaining same aft- and fore-wall dimensions, a counter rotating vortex characterized by better fuel-air mixing within the entire cavity domain can be established for MFR_C > 1 cases, which needs further investigation in future.