Impacts of longitudinal air velocity and fuel flow rate on flame radiative fraction in tunnel

TitleImpacts of longitudinal air velocity and fuel flow rate on flame radiative fraction in tunnel
Publication TypeJournal Article
Year of Publication2020
AuthorsLin Xu, Honghui Guo, Chao Ding, Yi Lu, Jinghan Liu
JournalSustainable Cities and Society
Volume61
Pagination102336
Date PublishedJan-10-2020
ISSN22106707
KeywordsExperimental evidence, Fuel flow rate, Longitudinal air velocity, Radiative fraction, Tunnel fire
Abstract

Fires in tunnels have attracted special attention in recent years due to catastrophic fires, which cause huge human and economic losses. For accurate fire modelling and ventilation system design, it is critical to understand the correct radiative fraction (Xr) of the flame. Recent study has proved that Xr decreases with the increase of longitudinal air velocity in heptane pool fires. However, the impacts of longitudinal air velocity and fuel flow rate on Xr in propane or liquefied petroleum gas tunnel fires have not been studied. To fill the gap, this paper conducts two sets of fire experiments in a 1/20 reduced-scale wind tunnel using a porous burner. Unique visible flame shapes are observed and described by the ‘back-to-back conical frustum’. The geometric parameters and their variations with the momentum flux ratio are discussed. In comparison with the experimental results, the radiation model using the proposed flame shape shows an 80 % accuracy. The predictive radiative fractions of the two tests are calculated and compared with other tests from literature. The coupling effects of longitudinal air velocity and fuel flow rate on the flame radiative fraction are studied in detail. And their influences on key parameters of smoke extraction system are analyzed.

DOI10.1016/j.scs.2020.102336
Short TitleSustainable Cities and Society