Measurement of laminar burning speed at high pressures using plasma affected flame

Abstract

Measurements of a propagating flame are crucial to the understanding and verification of important flame phenomena. Specifically, laminar, unstretched flame speed is desired to verify complex flame behavior such as turbulence or chemical kinetic models. This data is also necessary as advanced and more efficient combustion devices operate at these high pressures where this data is less reliable from the onset of flame instabilities. This research provides laminar burning speed (Suo) and Markstein length (Lb) measurements utilizing a novel technique which incorporates flame propagation during and just after the ignition phase. The analysis utilizes a constant pressure technique where the expansion of a spherical flame is visually measured. Flame propagation of stoichiometric flame from 1 to 50 atm are examined up to a radius of 20 mm. The inclusion of early flame propagation improves the measurement of Suo through the addition of a larger data set than usually possible in the conventional method. The measurement method utilizes electrical data of the spark formation with a thermodynamic model to predict the kernel velocity and temperature which result from plasma formation. In addition, morphology of the early kernel at high pressure is reported as well as comparisons to the conventional Suo measurement.