Numerical studies of turbulent premixed flame interaction with repeated solid obstacles

This paper presents numerical simulations of hydrogen and propane turbulent premixed flames interaction with repeated solid obstructions. The laboratory-scale combustion chamber used in this study is equipped with three solid baffles which promote the generation of turbulence and a square obstacle located downstream from the ignition source. The test cases considered have two different area blockage ratios (ABR) of 24% and 50%, respectively. The large eddy simulation (LES) turbulence modelling technique is used. The numerical simulations are carried out using an in-house computational fluid dynamics (CFD) model. Two different flow configurations are examined, both using three consecutive baffles to identify the subsequent effects and the sensitivity of each fuel to increasing the ABR. These effects are studied using the nature of the flame-obstacles interaction, generated combustion overpressure and resultant flame speed. The modelling capability is confirmed by validating the numerical results against published experimental data. Conclusions are drawn that increasing the ABR increases the combustion overpressure, rate of pressure rise and flame speed. It is also concluded that the larger obstacle has a significant effect on the propagating flame structure and that hydrogen flames are more sensitive to an increased ABR and produce a significantly higher peak overpressure.