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Title: The role of shock-flame interactions on flame acceleration in an obstacle laden channel

Abstract

Flame acceleration was investigated in an obstructed, square-cross-section channel. Flame acceleration was promoted by an array of top and bottom surface mounted obstacles that were distributed along the entire channel length at an equal spacing corresponding to one channel height. This work is based on a previous investigation of the effects of blockage ratio on the early stage of flame acceleration. This study is focused on the later stage of flame acceleration when compression waves, and eventually a shock wave, form ahead of the flame. The objective of the study is to investigate the effect of obstacle blockage on the rate of flame acceleration and on the final quasi-steady flame-tip velocity. Schlieren photography was used to track the development of the shock-flame complex. It was determined that the interaction between the flame front and the reflected shock waves produced from contact of the lead shock wave with the channel top, channel bottom, and obstacle surfaces govern the late stage of flame acceleration process. The shock-flame interactions produce oscillations in the flame-tip velocity similar to that observed in the early stage of flame acceleration, but only much larger in magnitude. Eventually the flame achieves a globally quasi-steady velocity. For the lowestmore » blockage obstacles, the velocity approaches the speed of sound of the combustion products. The final quasi-steady flame velocity was lower in tests with the higher obstacle blockage. In the quasi-steady propagation regime with the lowest blockage obstacles, burning pockets of gas extended only a few obstacles back from the flame-tip, whereas burning pockets were observed further back in tests with the higher obstacle blockage. (author)« less

Authors:
; ;  [1]
  1. Mechanical and Materials Engineering, Queen's University, Kingston, Ontario (Canada)
Publication Date:
OSTI Identifier:
21379819
Resource Type:
Journal Article
Journal Name:
Combustion and Flame
Additional Journal Information:
Journal Volume: 157; Journal Issue: 11; Other Information: Elsevier Ltd. All rights reserved; Journal ID: ISSN 0010-2180
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; FLAMES; ACCELERATION; VELOCITY; FLAME PROPAGATION; SHOCK WAVES; COMBUSTION PRODUCTS; BAFFLES; SOUND WAVES; COMPRESSION; OSCILLATIONS; SCHLIEREN METHOD; DUCTS; Flame acceleration; Shock-flame interactions

Citation Formats

Ciccarelli, Gaby, Johansen, Craig T, and Parravani, Michael. The role of shock-flame interactions on flame acceleration in an obstacle laden channel. United States: N. p., 2010. Web. doi:10.1016/J.COMBUSTFLAME.2010.05.003.
Ciccarelli, Gaby, Johansen, Craig T, & Parravani, Michael. The role of shock-flame interactions on flame acceleration in an obstacle laden channel. United States. https://doi.org/10.1016/J.COMBUSTFLAME.2010.05.003
Ciccarelli, Gaby, Johansen, Craig T, and Parravani, Michael. 2010. "The role of shock-flame interactions on flame acceleration in an obstacle laden channel". United States. https://doi.org/10.1016/J.COMBUSTFLAME.2010.05.003.
@article{osti_21379819,
title = {The role of shock-flame interactions on flame acceleration in an obstacle laden channel},
author = {Ciccarelli, Gaby and Johansen, Craig T and Parravani, Michael},
abstractNote = {Flame acceleration was investigated in an obstructed, square-cross-section channel. Flame acceleration was promoted by an array of top and bottom surface mounted obstacles that were distributed along the entire channel length at an equal spacing corresponding to one channel height. This work is based on a previous investigation of the effects of blockage ratio on the early stage of flame acceleration. This study is focused on the later stage of flame acceleration when compression waves, and eventually a shock wave, form ahead of the flame. The objective of the study is to investigate the effect of obstacle blockage on the rate of flame acceleration and on the final quasi-steady flame-tip velocity. Schlieren photography was used to track the development of the shock-flame complex. It was determined that the interaction between the flame front and the reflected shock waves produced from contact of the lead shock wave with the channel top, channel bottom, and obstacle surfaces govern the late stage of flame acceleration process. The shock-flame interactions produce oscillations in the flame-tip velocity similar to that observed in the early stage of flame acceleration, but only much larger in magnitude. Eventually the flame achieves a globally quasi-steady velocity. For the lowest blockage obstacles, the velocity approaches the speed of sound of the combustion products. The final quasi-steady flame velocity was lower in tests with the higher obstacle blockage. In the quasi-steady propagation regime with the lowest blockage obstacles, burning pockets of gas extended only a few obstacles back from the flame-tip, whereas burning pockets were observed further back in tests with the higher obstacle blockage. (author)},
doi = {10.1016/J.COMBUSTFLAME.2010.05.003},
url = {https://www.osti.gov/biblio/21379819}, journal = {Combustion and Flame},
issn = {0010-2180},
number = 11,
volume = 157,
place = {United States},
year = {Mon Nov 15 00:00:00 EST 2010},
month = {Mon Nov 15 00:00:00 EST 2010}
}