Numerical simulation of a modified trapped vortex combustor

Abstract

Analysing the flow inside the combustor is important for determining the performance and NOx emission of the combustors. This study investigated combustion and flow characteristics inside a modified trapped vortex combustor (TVC) to enhance the performance and reduce the NOx emission. The modified TVC was characterised by a variable guide vane ratio between length of column guide vane inside cavity and height of the cavity. The effect of the incoming velocity was analysed. The Arrhenius rate of the one-step methane/air reaction mechanism was used. Validation of the study results was performed by comparing the present numerical results with the published experimental results. Numerical results demonstrated significant changes in the vortex inside the cavity after introducing the guide vane. Furthermore, variable guide vane ratio was found to have a significant effect on temperature, NOx emission, and combustion efficiency with reduction of 5, 90, and 2%, respectively, at guide vane ratio 0.75. The guide vane ratio of 0.5 was found to be the cutoff design for the current TVC model. Increasing the guide vane ratio larger than 0.5 was found to reduce the NOx emission but needed to compensate with drop of the combustion efficiency. This study has improved the understanding of the effect of the guide vane on the development of a high-efficiency low-NOx TVC.