Conditional Velocity Measurements by Simultaneously Applied Laser Doppler Velocimetry and Planar Laser-Induced Fluorescence in a Swirling Natural Gas/Air Flame

摘要

By applying joint velocity/scalar measurements,conditional mean axial and radial velocity components are determined in the vicinity of the turbulent flame front of a premixed swirling natural gas/air flame.Two velocity components are measured by laser Doppler velocimetry (LDV) simultaneously with planar laser-induced fluorescence (PLIF) monitoring the hydroxyl radical (OH).The spatial OH distribution is used to tag the instantaneous position of the flame front and can be thereby used to derive conditional velocities.From these measurements the turbulent flux of the mean progress variable is determined which is an important quantity to model premixed flames.One important finding is that for this rather complex but technically realistic geometry,at some locations in the flame brush conditional axial and radial velocities show different behaviour.Thus gas expansion effects can dominate axially whereas in radial direction turbulent fluctuations determine the direction of turbulent transport.