Reaction rates in premixed turbulent flames and their relevance to the turbulent burning speed
An experimental procedure to measure the local reaction rate, /bar char/w, in premixed turbulent flames is presented. It utilizes the flame crossing frequency sub-model for the reaction rate formulated by Bray-Champion-Libby (BCL) for turbulent flames with unstrained or equally strained flamelets. The experiments involve measuring the flame crossing frequencies and the conditioned mean velocity of two components using respectively Mie scattering and two color LDA techniques. A method of analysis has also been developed to deduce the turbulent burning speed from /bar char/w. The turbulent/laminar burning speed ratio is obtained by integrating the reaction rates measured along 2D mean Lagrangian flowlines through the flame brush. The flowlines are traced automatically using feedback control for positioning the LDA probe. The method has been applied to study five v-flames and four large Bunsen type conical flames. The distributions of /bar char/w are well predicted by the BCL model. The turbulent flame speed results based on /bar char/w are in excellent agreement with those obtained by the conventional flame orientation method. The main advantage of using this method to determine the turbulent burning speed is that the uncertainties are lowered. Furthermore, it can be applied successfully to flames with complex geometries such as the flame tip region of a conical flame. 22 refs., 5 figs., 2 tabs.
- Research Organization:
- Lawrence Berkeley Lab., CA (USA)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 6908473
- Report Number(s):
- LBL-25230; CONF-880802-8; ON: DE88012021
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALKANES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMBUSTION
COMBUSTION KINETICS
FLAME PROPAGATION
FLAMES
HYDROCARBONS
KINETICS
METHANE
ORGANIC COMPOUNDS
OXIDATION
REACTION KINETICS
THERMOCHEMICAL PROCESSES
TURBULENCE