Temperature profile and flame extension length of a ceiling impinging round jet fire in an inclined tunnel

Abstract

Abstract Ceiling jet fire may popularly occur due to gas fuel leakage caused by corrosion of the pipeline in underground galleries or other accidental factors, and usually inflict major heat hazards and related risks. So the characteristics of a ceiling impinging flow induced by a jet fire in an inclined tunnel are valuable to be investigated. Therefore, the temperature profile and flame extension length along an inclined tunnel ceiling in upward and downward directions under different initial fuel momentums and tunnel inclination angles are obtained and analysed. The results show that the flame extension length in both directions along the ceiling can be correlated with flame free height, inclination angles and height between the fire source and ceiling accounting for the non-symmetrical distribution of un-burnt fuel after impingement. Furthermore, the temperature profile of the ceiling jet is obviously affected by the source initial momentum comparing to the flames with negligible initial momentum. New correlations for predicting the temperature decay profiles are proposed considering the source Froude number and inclination angles. The results of this paper would be valuable for modelling of a ceiling jet fire in inclined tunnel or providing significant guidance/raw data for protection and risk assessment of such fire scenarios.