Thermal and flow structures of a porous burner flame and an array of micro flame burners: Implications to simulate large scale mass fires and fire whirls in laboratory

Ahmad A. Salaimeh, Taro Hirasawa, Manabu Fuchihata, Nelson Akafuah, Kozo Saito

Research output: Contribution to conferencePaperpeer-review

Abstract

This paper addresses thermal and fluid dynamic structures of diffusion flames created by a 6.86 cm diameter porous burner and a micro flame burner array consisting of 56 of a 1 mm diameter micro flame burner which are equal distantly arranged in a hexagonal shape. Propane was issued from each burner to establish diffusion flames under different fuel flow rates. Flame height and a 2-D side view of flame shape were measured by a high speed camera and an Infrared thermography camera at 100 frames/s rate, and transient 3-D numerical simulation was conducted using rhoReactingBuoyantFoam of OpenFOAM2.3.0 to calculate flow structures around the flame. Temperature and fluid dynamic structures of the porous burner flames resembled pool fires, while those structures of the array of micro flames were different, particularly in their flame base and flame share. This difference was more obvious when circulation was imposed to each flame: the porous burner flames increased flame height with an increase in circulation, while the array of micro flames decreased. This difference is explained by the 3-D numerical model calculation, and suggests the array of micro flames to be closer to the structure of large scale mass fires where the flame height was first increased with an imposed circulation, then decreased with an increase in circulation. This result is indicating the use of the array of micro flames for simulating large scale mass fire behavior, contrary to the traditional pool fires.

Original languageEnglish
StatePublished - 2017
Event10th U.S. National Combustion Meeting - College Park, United States
Duration: Apr 23 2017Apr 26 2017

Conference

Conference10th U.S. National Combustion Meeting
Country/TerritoryUnited States
CityCollege Park
Period4/23/174/26/17

Bibliographical note

Funding Information:
Our numerical simulation showed that the observed difference in the swirl effect on the flame height is due to the difference in circulation and velocity structures of PBF and MBF. With swirl, PBF can extend the tangential velocity to the upper flame location due to no airflow into the flame core, while MBF has sufficient airflow into the flame core so that the imposed swirl can promote combustion rate making the total flame height short. MBF exhibited more similar flame characteristics to large scale mass fires than PBF flames. Further studies are needed to quantify the scaling between MBF and large scale mass fires. 5. Acknowledgements This study was partially funded by USDA Forest Service in Missoula, MT 6. References [1] K. Saito and F.A. Williams, in: K. Saito, A. Ito, Y. Nakamura, K. Kuwana (Eds.), Progress in Scale Modeling, Volume II, Springer Int. Pub., Cham, Switzerland, (2015), p. 1. [2] G.I. Tayler, in: W.G. Berl (Eds.), International Symposium on the use of models in fire research, US National Academy of Science, Washington D.C., (1961), p. 10. [3] H.C. Hottel, in: W.G. Berl (Eds.), International Symposium on the use of models in fire research, US National Academy of Science, Washington D.C. , (1961), p. 32. [4] D.B. Spalding, Proc. Combust. Inst. 9 (1963) 833-843. 
 [5] H.W. Emmons, in: W.G. Berl (Eds.), International Symposium on the use of models in fire research, US National Academy of Science, Washington D.C., 1961, p. 50. [6] F.A. Williams, Fire Research Abstracts and Reviews 11 (1969) 1-23. 
 [7] I. Emori, K. Saito, K. Sekimoto, Scale Models in Engineering, Third Edition, Gihodo, Tokyo, 2000. [8] M.A. Finney, J.D. Cohen, J.M. Forthofer, S.S. McAllister, M.J. Gollner, D.J. Gorham, K.

Publisher Copyright:
© 2017 Eastern States Section of the Combustion Institute. All rights reserved.

Keywords

  • Fire research
  • Fire whirls
  • Infrared thermography
  • Micro flame
  • Scaling

ASJC Scopus subject areas

  • Chemical Engineering (all)
  • Physical and Theoretical Chemistry
  • Mechanical Engineering

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