CaltechAUTHORS
  A Caltech Library Service

Ignition of fuel–air mixtures from a hot circular cylinder

Boeck, Lorenz R. and Meijers, Maxime and Kink, Andreas and Mével, Rémy and Shepherd, Joseph E. (2017) Ignition of fuel–air mixtures from a hot circular cylinder. Combustion and Flame, 185 . pp. 265-277. ISSN 0010-2180. http://resolver.caltech.edu/CaltechAUTHORS:20170809-090456062

[img] PDF - Published Version
See Usage Policy.

3356Kb

Use this Persistent URL to link to this item: http://resolver.caltech.edu/CaltechAUTHORS:20170809-090456062

Abstract

Ignition of hydrogen–air, ethylene–air and n-hexane–air mixtures from a horizontally and vertically oriented heated circular cylinder was studied experimentally in a wide range of equivalence ratio. Initial pressure and temperature were 101.3 kPa and 296 K, respectively. The cylinder with outer diameter 10 mm and heated length 10 mm was designed for high temperature uniformity. Two-color pyrometry measured the surface temperature; Time-resolved Mach–Zehnder interferometry acquired ignition dynamics, gas temperature fields and heat transfer characteristics. Ignition from the horizontal cylinder occurred at temperatures between 960 K and 1100 K for hydrogen, between 1060 K and 1110 K for ethylene, and between 1150 K and 1190 K for n-hexane. Vertical cylinder orientation increased ignition thresholds by 50–110 K for ethylene and n-hexane, whereas only little variation was observed for hydrogen. Infinite-fringe interferograms visualized the ignition dynamics and identified the most favorable ignition locations, which coincided with locations of lowest wall heat flux (largest thermal boundary layer thickness) and long residence time. Gas temperature fields were obtained by post-processing the interferograms, resolving the temporal and spatial development of thermal boundary layers and enabling local heat transfer analysis. The convective pattern around a horizontal cylinder features distinctly shallow temperature gradients, i.e., low heat flux, at the cylinder top due to thermal plume formation, which promotes ignition compared to the vertical cylinder. An analytical scaling model for ignition from hot surfaces was evaluated to determine the sensitivity of ignition threshold to heat transfer variations, and to reveal the influence of chemical mixture properties. This analysis predicts a particularly low sensitivity for hydrogen–air mixtures at temperatures near the extended second explosion limit, and a larger sensitivity of ethylene–air and n-hexane–air mixtures, which is in accordance with the experiments.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1016/j.combustflame.2017.07.007DOIArticle
http://www.sciencedirect.com/science/article/pii/S0010218017302523PublisherArticle
ORCID:
AuthorORCID
Shepherd, Joseph E.0000-0003-3181-9310
Additional Information:© 2017 The Combustion Institute. Published by Elsevier Inc. Received 15 March 2017, Revised 10 July 2017, Accepted 10 July 2017, Available online 9 August 2017. The present work was carried out in the Explosion Dynamics Laboratory of the California Institute of Technology and was supported by The Boeing Company through a Strategic Research and Development Relationship Agreement CT-BA-GTA-1. The authors thank Dr. Stephanie Coronel for her contributions to the Fourier analysis of interferograms.
Funders:
Funding AgencyGrant Number
Boeing Company Strategic Research and Development Relationship CT-BA-GTA-1
Subject Keywords:Hot surface ignition; Cylinder; Interferometry; Heat transfer
Record Number:CaltechAUTHORS:20170809-090456062
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20170809-090456062
Official Citation:Lorenz R. Boeck, Maxime Meijers, Andreas Kink, Remy Mével, Joseph E. Shepherd, Ignition of fuel–air mixtures from a hot circular cylinder, Combustion and Flame, Volume 185, November 2017, Pages 265-277, ISSN 0010-2180, https://doi.org/10.1016/j.combustflame.2017.07.007. (http://www.sciencedirect.com/science/article/pii/S0010218017302523)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:79998
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:09 Aug 2017 16:21
Last Modified:09 Aug 2017 16:21

Repository Staff Only: item control page