Effect analysis on performance enhancement of a hydrogen/air non-premixed micro combustor with sudden expansion and contraction structure

Improvement of combustion stability and efficiency is still the main challenge of micro combustors. In this work, a non-premixed combustion model of the hydrogen/air in a dimensionless micro combustor with sudden expansion and contraction structure at the entrance is established. The effects of different micro combustor diameters, inlet velocities and wall materials on non-premixed combustion performance enhancement of the hydrogen/air in the micro combustor is investigated. By comparing the temperature distribution and combustion efficiency of the micro combustor, the combustion characteristics of the hydrogen/air under different influence factors are obtained. The results show that the appropriate diameter of the micro combustor and the inlet velocity are of a great influence on the stable combustion. Furthermore, the field synergy analysis between temperature gradient and velocity vector fields under different inlet velocities of hydrogen/air is carried out, and an enhanced combustion method is proposed in this work. The calculation results show that the inlet velocity decrescence of the hydrogen can significantly improve combustion stability under constant inlet velocity of air condition, which will be useful for stabilizing non-premixed combustion in the micro combustor. (c) 2021 Elsevier Ltd. All rights reserved.