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Title: Influence of smooth temperature variation on hotspot ignition

Autoignition in thermally stratified reactive mixtures originates in localised hotspots. The ignition behaviour is often characterised using linear temperature gradients and more recently constant temperature plateaus combined with temperature gradients. Acoustic timescale characterisation of plateau regions has been successfully used to characterise the type of mechanical disturbance that will be created from a plateau core ignition. This work combines linear temperature gradients with superelliptic cores in order to more accurately account for a local temperature maximum of finite size and the smooth temperature variation contained inside realistic hotspot centres. A one-step Arrhenius reaction is used to model a H 2–air reactive mixture. Using the superelliptic approach a range of behaviours for temperature distributions are investigated by varying the temperature profile between the gradient only and plateau and gradient bounding cases. Each superelliptic case is compared to a respective plateau and gradient case where simple acoustic timescale characterisation may be performed. It is shown that hot spots equivalent with excitation-to-acoustic timescale ratios sufficiently greater than unity exhibit behaviour very similar to a simple plateau-gradient model. Furthermore, for larger hot spots with timescale ratios sufficiently less than unity the reaction behaviour is highly dependent on the smooth temperature profile contained within themore » core region.« less
Authors:
 [1] ; ORCiD logo [1]
  1. Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
LA-UR-17-28265
Journal ID: ISSN 1364-7830; TRN: US1801000
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Combustion Theory and Modelling
Additional Journal Information:
Journal Volume: 22; Journal Issue: 1; Journal ID: ISSN 1364-7830
Publisher:
Taylor & Francis
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
Universities/Institutions; USDOE
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 54 ENVIRONMENTAL SCIENCES; hotspot; acoustic timescale; thermal stratification; temperature gradient; detonation
OSTI Identifier:
1417170

Reinbacher, Fynn, and Regele, Jonathan David. Influence of smooth temperature variation on hotspot ignition. United States: N. p., Web. doi:10.1080/13647830.2017.1381347.
Reinbacher, Fynn, & Regele, Jonathan David. Influence of smooth temperature variation on hotspot ignition. United States. doi:10.1080/13647830.2017.1381347.
Reinbacher, Fynn, and Regele, Jonathan David. 2017. "Influence of smooth temperature variation on hotspot ignition". United States. doi:10.1080/13647830.2017.1381347. https://www.osti.gov/servlets/purl/1417170.
@article{osti_1417170,
title = {Influence of smooth temperature variation on hotspot ignition},
author = {Reinbacher, Fynn and Regele, Jonathan David},
abstractNote = {Autoignition in thermally stratified reactive mixtures originates in localised hotspots. The ignition behaviour is often characterised using linear temperature gradients and more recently constant temperature plateaus combined with temperature gradients. Acoustic timescale characterisation of plateau regions has been successfully used to characterise the type of mechanical disturbance that will be created from a plateau core ignition. This work combines linear temperature gradients with superelliptic cores in order to more accurately account for a local temperature maximum of finite size and the smooth temperature variation contained inside realistic hotspot centres. A one-step Arrhenius reaction is used to model a H2–air reactive mixture. Using the superelliptic approach a range of behaviours for temperature distributions are investigated by varying the temperature profile between the gradient only and plateau and gradient bounding cases. Each superelliptic case is compared to a respective plateau and gradient case where simple acoustic timescale characterisation may be performed. It is shown that hot spots equivalent with excitation-to-acoustic timescale ratios sufficiently greater than unity exhibit behaviour very similar to a simple plateau-gradient model. Furthermore, for larger hot spots with timescale ratios sufficiently less than unity the reaction behaviour is highly dependent on the smooth temperature profile contained within the core region.},
doi = {10.1080/13647830.2017.1381347},
journal = {Combustion Theory and Modelling},
number = 1,
volume = 22,
place = {United States},
year = {2017},
month = {10}
}