Experimental investigation of a premixed laminar flame stabilized on a cylindrical rod confined in a rectangular duct

Laminar flames, in which the effect of turbulent diffusion is non-present, are widely used in the literature to study the flame structure, combustion chemistry and flame behavior under acoustic fluctuations. In this study a laminar flame stabilized on a cylindrical rod confined in a rectangular duct is investigated experimentally by utilizing CH* emission photographs; which is found to be a good representation of the qualitative heat release in hydrocarbon flames, to obtain the position of the flame and PIV measurements to acquire the velocity field prior to the flame and in a part of the chamber which can be accessed by the field of view of the camera for non-reacting cases. Also, open source CFD software OpenFOAM and AVBP CFD code developed by CERFACS (Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique) has been utilized to simulate the flow to be compared to the experiments for the assessment of the degree of agreement. These measurements and calculations are then be used to study the flame stabilization mechanism on the rod. The CFD calculations for the non-reacting cases and the experiments have been used to study the Karman vortex shedding phenomenon and the location of the boundary layer separation points. When the rod is actuated, the effect of the speed of rotation of the rod on the vortex shedding mechanism and the lift coefficient has been investigated. As the flame quenching distance is depending on the wall temperature of the rod, combustion chemistry and the effects of strain, the flame root position will be greatly affected by the composition of the mixture and the wall temperature of the rod. This study also includes non-stretched and stretched laminar flame speed, auto ignition delay time and equilibrium calculations for different conditions performed by open source chemistry solver CANTERA using different chemical mechanisms. As it is considered to be a good alternative to fossil fuels, there is specific interest on the effects of hydrogen addition to the primary fuel which is methane and the effects of hydrogen addition on flame speeds, extinction strain rates and equilibrium temperatures have been investigated. For the methane/air and hydrogen enriched methane air flames that have the same freely propagating flame speeds stretched flame speeds and CFD calculations of the experimental setup has been performed to assess the effect of hydrogen on stretched flame speeds and the flame stabilization mechanism on the rod.