Sidewall quenching of atmospheric laminar premixed flames studied by laser-based diagnostics

Flame-wall interactions (FWI) of laminar premixed methane-air flames at atmospheric pressure are studied using various laser diagnostic methods. Velocity fields and flame front locations are measured simultaneously by two-component particle image velocimetry (PIV) and planar laser induced fluorescence (LIF) of the OH-radical. Coherent anti-Stokes Raman spectroscopy (CARS) and two-photon LIF of the CO molecule are used to determine temperatures and CO concentrations. The FWI process is investigated using a generic burner setup with well-defined boundary conditions, where one branch of a V-shaped flame interacts with a water-cooled stainless steel wall, corresponding to a sidewall quenching (SWQ) geometry. FWI is studied for equivalence ratios of ϕ = 0.83, 1.0 and 1.2. The quenching distance of the flames is determined using two different methods. Additionally, the near wall behavior of the flame consumption speed is analyzed and compared with that of a freely propagating laminar flame. Thermochemical properties are analyzed using CO/T-state diagrams. Comparison to one-dimensional laminar flame calculations undisturbed by the presence of a wall highlights the severe impact upon thermochemical states. Comparing characteristic time scales of heat transfer processes to chemical processes indicates that diffusion rather than chemical reaction processes is the reason for these observations.