Experimental Study and CFD Modelling of Down-Reaching Flame Behaviors of Tank Fires with Large Ullage Heights

Jinlong Zhao, Zhenqi Hu, Xinjiang Li, Jie Ji, Rui Yang, Jianping Zhang, Yunfei Zhong

Research output: Contribution to journalArticlepeer-review


This paper is aimed at studying the down-reaching flame behaviors of tank fires with large ullage heights. Experiments were first conducted using a gas burner in a transparent quartz glass cylinder to simulate the large ullage and the experimental data was used to validate the computational fluid dynamics (CFD) model. Subsequently the effects of ullage height, fuel velocity and burner diameter on the flame behaviors were examined systematically. Both experimental and numerical results showed that, for lower fuel velocities, the down-reaching flame height (hdown) is restricted by the ullage height. As the fuel velocity continues to increase exceeding a critical value, independent of the ullage height, hdown starts to decrease. For a given fuel velocity, hdown increases with an increase of the burner diameter owing to enhanced air entrainment. A detailed analysis of the flow field and oxygen concentration inside the tank at the steady burning stage was also carried out. Based on the numerical results and dimensionless analysis, a piecewise function was proposed to predict the down-reaching flame height and validated against the experimental data.
Original languageEnglish
JournalFire Technology
Early online date22 Mar 2024
Publication statusPublished online - 22 Mar 2024

Bibliographical note

Publisher Copyright:
© The Author(s) 2024.


  • Flame behaviors
  • Large ullage
  • Down-reaching flame
  • Tank fire
  • CFD modelling


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