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Prediction of premixed, n-heptane and iso-octane unopposed jet flames using a reduced kinetic model based on constituents and light species

Harstad, Kenneth and Bellan, Josette (2013) Prediction of premixed, n-heptane and iso-octane unopposed jet flames using a reduced kinetic model based on constituents and light species. Combustion and Flame, 160 (11). pp. 2404-2421. ISSN 0010-2180. http://resolver.caltech.edu/CaltechAUTHORS:20131003-081047378

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Abstract

A model of steady, quasi one-dimensional premixed laminar jet flame developing unopposed into a uniform flow has been formulated using a previously successful reduced chemical-kinetics model [10] and [11]. A detailed derivation of the steady quasi one-dimensional conservation equations revealed that it is only under very restrictive conditions – probably very difficult to achieve experimentally and the validity of which is not reported in detail in experimental studies – that the quasi one-dimensional concept is meaningful. The governing equations have been mathematically manipulated to be consistent with the framework of the reduced chemical-kinetics model which relied on constituents representing the heavy species, and on quasi-steady light species and unsteady light species. The flame model includes accurate transport property calculation for high-pressure conditions and a real-gas equation of state. Based on a found self-similarity [10] and [11] which deteriorates at increasingly rich conditions, the chemistry model consists of tables of kinetic rates, quasi-steady species molar fractions and the heavy species mean molar mass extracted from the LLNL model in the framework of the reduced kinetics. The progress variables are only the mass fractions of the unsteady light species and the temperature. The values of the dependent variables are specified at the inflow location and null gradients are specified at the outflow. Simulations were performed for both n-heptane and iso-octane air oxidation over a wide range of pressures and equivalence ratios. The limited documentation of experimental conditions not specifying the inflow velocity (or flux) made it impossible to use this data for detailed comparison. In the one case where the inflow velocity was available for a burner experiment, those conditions were adopted for the simulation and the configuration was changed to a constant-area jet to approach the burner configuration. Results from this simulation compared favorably with the data, considering the different configurations. Results from parametric studies not associated with experimental data showed that at stoichiometric conditions the flame temperature, flame velocity and strain rate are not sensitive to the pressure, although flames become increasingly thinner with increasing pressure and the yield of the unsteady light species is different. Computations conducted at 40 bar for various equivalence ratios and for velocities differing with the equivalence ratio showed that the maximum flame velocity, flame strain and flame temperature were obtained at stoichometric conditions. Finally, we discuss the limitations of utilizing a priori obtained reduced chemical-kinetic models in flames calculations.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.combustflame.2013.06.005 DOIArticle
http://www.sciencedirect.com/science/article/pii/S0010218013002174PublisherArticle
Additional Information:© 2013 The Combustion Institute. Published by Elsevier Inc. Received 17 January 2013; Received in revised form 17 April 2013; Accepted 1 June 2013; Available online 29 June 2013. This study was conducted at the California Institute of Technology, Jet Propulsion Laboratory (JPL), and was sponsored by the Army Research Office, with Dr. Ralph Anthenien as Program Manager. Computations were performed using the JPL Supercomputing facility.
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Funding AgencyGrant Number
Army Research Office (ARO)UNSPECIFIED
Subject Keywords:Premixed laminar flame prediction using reduced kinetics
Record Number:CaltechAUTHORS:20131003-081047378
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20131003-081047378
Official Citation:Kenneth Harstad, Josette Bellan, Prediction of premixed, n-heptane and iso-octane unopposed jet flames using a reduced kinetic model based on constituents and light species, Combustion and Flame, Volume 160, Issue 11, November 2013, Pages 2404-2421, ISSN 0010-2180, http://dx.doi.org/10.1016/j.combustflame.2013.06.005. (http://www.sciencedirect.com/science/article/pii/S0010218013002174)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:41646
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:03 Oct 2013 16:24
Last Modified:03 Oct 2013 16:24

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