Aerodynamic Assessment of Periodicity and Symmetry Conditions in a Flameless Burner

Despite the significant advances achieved through the years, researchers in numerical simulation has investigated symmetry and periodicity conditions to reduce the computational time. Especially, it becomes essential this assessment in problems involving both combustion and detailed reactions mechanisms, as well as when new technologies are being evaluated. Therefore, aerothermodynamics conditions in a given periodic section, will be considered in the opposite section, assuming identical conditions in other sectors that compose the full scale domain. At this point, the definition of this representative region has been a major source of errors once the selected sector can not represent the full domain, leading to coarse approximations of the real phenomenon. In this context, this paper investigates the effects of periodicity and symmetry condition in a burner designed for flameless combustion regime. This new combustion system exhibits a strong internal recirculation and very specific characteristics that can contribute to the flow profile. Numerical simulations were performed in ANSYS FLUENT®. Based on the results, the periodicity condition in a 1/16 sector showed discordant results with those obtained in the simulations with a full scale burner and by comparing with the experimental data available. However, by employing the symmetry condition, numerical results were close to those results involving a full scale domain, reinforcing the importance of investigate carefully the use of such strategies.