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Hot surface ignition of n-hexane in air

Menon, Shyam K. and Boettcher, Philipp A. and Ventura, Brian and Blanquart, Guillaume (2016) Hot surface ignition of n-hexane in air. Combustion and Flame, 163 . pp. 42-53. ISSN 0010-2180. http://resolver.caltech.edu/CaltechAUTHORS:20151019-143526927

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Abstract

An experimental investigation is conducted to analyze hot-surface ignition of n-hexane-air mixtures. The experimental setup, equipped with temperature diagnostics and schlieren imaging, utilizes a glow plug to initiate ignition in a flammable mixture. The hot-surface temperature at the point of ignition is measured for equivalence ratios ranging from 0.6 to 3 and chamber pressures varying from 25 to 100 kPa. The hot-surface temperature resulting in ignition is found to be weakly sensitive to equivalence ratio with a mean value of 980 K for mixtures with equivalence ratios between 0.75 and 3 at 100 kPa. Chamber pressure has a stronger influence with ignition temperature increasing to about 1140 K at 25 kPa. The experimental trends were reproduced in numerical simulations utilizing detailed chemistry of n-heptane as a surrogate for n-hexane given their similar ignition and flame propagation characteristics. The simulations further predict a two-stage ignition process resulting from an initial breakdown of the fuel with a small increase in temperature followed by a main ignition event accompanied by fuel depletion. Reaction rate analysis of the sequence of events leading to ignition conducted using a reduced order kinetic model suggests that the second-stage ignition event is caused primarily by the decomposition of hydrogen peroxide which occurs at temperatures above 900 K. The two-stage ignition process observed here is significantly different from that observed in previous studies due to the presence of convective and diffusive processes as well as the continuous increase in hot-surface temperature. These arguments are used to explain the insensitivity of ignition temperature to equivalence ratio, its decrease with increasing chamber pressure, and the location of the ignition kernel observed in experiments and simulations.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.combustflame.2015.08.011DOIArticle
http://www.sciencedirect.com/science/article/pii/S0010218015002722PublisherArticle
ORCID:
AuthorORCID
Blanquart, Guillaume0000-0002-5074-9728
Additional Information:© 2015 The Combustion Institute. Published by Elsevier Inc. Received 6 February 2015, Revised 19 August 2015, Accepted 19 August 2015, Available online 11 October 2015. The authors gratefully acknowledge funding for this research by the Boeing Company through a Strategic Research and Development Relationship Agreement CT-BA-GTA-1. The authors would also like to thank Prof. Joseph Shepherd for valuable discussions throughout the project.
Funders:
Funding AgencyGrant Number
Boeing Company Strategic Research and Development Relationship CT-BA-GTA-1
Subject Keywords:Hot-surface ignition; Two-stage ignition; Detailed chemistry; Hexane; Heptane
Record Number:CaltechAUTHORS:20151019-143526927
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20151019-143526927
Official Citation:Shyam K. Menon, Philipp A. Boettcher, Brian Ventura, Guillaume Blanquart, Hot surface ignition of n-hexane in air, Combustion and Flame, Volume 163, January 2016, Pages 42-53, ISSN 0010-2180, http://dx.doi.org/10.1016/j.combustflame.2015.08.011. (http://www.sciencedirect.com/science/article/pii/S0010218015002722)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:61287
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:19 Oct 2015 21:54
Last Modified:13 Jan 2016 23:19

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