Optimizing thermal performance and exergy efficiency in hydrogen-fueled meso-combustors by applying a bluff-body

Recognizing the importance of a bluff-body on the flow separation and its role in enhancing the fuel mixing, the effect of applying a bluff-body on the thermal performance and exergy efficiency in hydrogen-fueled meso-scale combustors are discussed using 3D numerical simulations involving a detailed kinetics mechanism. Key parameters including the bluff-body dimensionless axial location l and combustor configuration are evaluated to obtain the optimal geometry. It is found that the bottom wall mean temperature (BWMT) and its uniformity are significantly enhanced with a bluff-body applied, generally accompanied with a high average Nusselt number. This is mainly due to the fact that the bluff-body can create longitudinal vortices and disrupts the growth of the thermal boundary layer, leading to intensified heat transfer. There is a non-monotonic relationship between BWMT and l with the optimum position being l = 2/5. Further, the proposed Combustor A is involved with a higher and more uniform BWMT. Finally, the exergy efficiency in the bluff-body combustor is found to be higher compared to the conventional combustor, although the elevated pressure loss. This work demonstrates the feasibility of implementing a bluff-body to enhance the thermal performance, and some of the interesting findings can be also applied to power and propulsion systems utilizing the combustor wall temperature.

Automated summary

This study discusses the effects of applying a bluff-body on the thermal performance and exergy efficiency in hydrogen-fueled meso-scale combustors, with evaluations of key parameters and optimal geometry obtained through numerical simulations. The results show significant improvements in the bottom wall mean temperature and exergy efficiency with a bluff-body applied, demonstrating the feasibility of enhancing thermal performance in combustors.