Performance Evaluation of H2/Air Premixed Combustion in a Suddenly Expanded Microcombustor with Wall Fin

Abstract

Herein, a 2D, axisymmetric microcombustor with a backward‐facing step and triangular wall fin is considered for enhancement of combustor performance. The outer wall temperature, combustor efficiency, and pressure characteristics of the microcombustor are numerically investigated with a detailed chemical kinetic mechanism and conjugate heat transfer. The proposed microcombustors with variable blockage ratios, wall fin shapes, and locations are analyzed with respect to flow and combustion interaction, along with heat flux exchange between the flame and combustor wall. Combustion performance is also evaluated by means of the amount of heat transferred through the combustor wall, conversion ratio of input chemical energy to exploitable heat, and OH mass fraction distributions. Standard k–ε turbulence along with 9 species and the 19‐step combustion reaction scheme is implemented using the eddy dissipation concept (EDC) model in the numerical study. The results indicate that the wall fin blockage ratio alters the reaction zone and improves combustor performance significantly at lower inlet velocities (4–20 m s−1). The fin location and shape are observed to influence the temperature distribution. However, the higher blockage ratio adversely impacts the combustion characteristics at the higher inlet velocity, that is, 48 m s−1.