Turbulent consumption speed via local dilatation rate measurements in a premixed bunsen jet

The mean local reaction rate related to the average expansion across the front and computed from the mean velocity divergence is evaluated in this work. Measurements are carried out in a air/methane pre-mixed jet flame by combined PIV/LIF acquisitions. The procedure serves the purpose of obtaining values of a turbulent flame speed, namely the local turbulent consumption speed S-LC, as a function of the position along the bunsen flame. With the further position that the flamelet assumption provides a proportionality between turbulent burning speed normalized with the laminar unstretched one and the turbulent to average flame surface ratio, the proportionality constant, i.e., the stretching factor becomes available. The results achieved so far show the existence of a wide region along which the bunsen flame front has a constant stretching factor which apparently depends only on the ratio between turbulent fluctuations and laminar flame speed and on the jet Reynolds number. (C) 2013 The Combustion Institute. Published by Elsevier Inc. All rights reserved.