Systematic experiments on turbulent premixed Bunsen flames including turbulent flux measurements

The existence of good experimental data for turbulent premixed flames is of interest for the development and validation of numerical models. In this paper special focus is laid on the systematic variation of either the fuel–air ratio with fixed flow rate or varied flow and turbulence with fixed composition. In total, 15 different turbulent Bunsen flames are investigated. With the planar conditioned particle image velocimetry (CPIV) technique, simultaneous access is given to the flow, turbulence, and flame position data, using PIV for flow and turbulence and the density jump at the instantaneous flame front for reaction progress variable and density. This allows the fast determination of a large amount of statistical data such as Reynolds- and Favre-averaged mean reaction progress and velocities, which are needed for the density-weighted sets of equations used in the numerical codes. Additionally, conditioned and unconditioned mean velocities and velocity fluctuations can be determined and the turbulent flux terms of the reaction progress variable can be measured directly. Thus, a comprehensive data set is presented, which can be used for validation studies. The measured turbulent flux is compared with two models, the gradient diffusion assumption and a relation proposed by Veynante et al. that accounts for the competition between gas-dynamic expansion and turbulent mixing. While the former approach fails, the latter shows reasonable agreement for the radial flux and also accounts for the trend observed for the varied flow or flame conditions. The axial turbulent flux near the tip of the flame is not fully resolved.