Particle streak velocimetry and CH laser-induced fluorescence diagnostics in strained, premixed, methane-air flames

We present the use of simultaneous Particle Streak Velocimetry (PSV) and CH Planar Laser Induced Fluorescence (PLIF) diagnostics in the study of planar, strained, premixed, methane-air flames, stabilized in a jet-wall stagnation flow. Both PSV and PLIF data are imaged at high spatial resolution and sufficiently high framing rates to permit an assessment of flame planarity and stability. Concurrent measurements of mixture composition, (Bernoulli) staticpressure drop, and stagnation-plate temperature provide accurate boundary conditions for numerical simulations. The new PSV implementation is characterized by very low particle loading, high accuracy, and permits short recording times. This PSV implementation and analysis methodology is validated through comparisons with previous laminar flame speed data and detailed numerical simulations. The reported diagnostic suite facilitates the investigation of strained methane-air flames, as a function of nozzle-plate separation to jet-diameter ratio, L/d, and equivalence ratio, Φ. Flames are simulated using a one-dimensional streamfunction approximation, with full chemistry (GRI-Mech 3.0), and multi-component transport. In general, we find good agreement between experiments and simulations, if boundary conditions are specified from measured velocity fields. Methane-air flame strength appears to be slightly overpredicted, with the largest disagreements for lean flames.