Two-Dimensional Analysis on Ceiling Jet Temperature Characteristics in a Semicircular Tunnel

In order to reveal the evolution of ceiling jet temperature characteristics beneath curved ceiling in two-dimensional view, experimental and theoretical studies were conducted to analyze the vertical temperature profile and longitudinal temperature attenuation beneath a curved ceiling of a semicircular tunnel. The temperature profile was first measured from experiments carried out in the model-scale semicircular tunnel. The relationship between temperature and the horizontal positions is described by an empirical model. A formula describing the thickness of the thermal boundary layer is proposed, based on the vertical distribution of smoke temperature. An engineering model for the longitudinal attenuation of the gas temperature with different fire plume types at impingement region is established in terms of conservation equations. After validation, model predictions show a good agreement with trend proposed by former literature and the relative error of prediction is found to be within 10%. Two-dimensional prediction for temperature profile beneath semicircle ceiling centerline was proposed. It was noted that two-dimensional prediction model could predict majority of measured data within 20% relative error even though some fluctuation, which could be applied to the fire protection engineering in semicircular tunnel.

Automated summary

Experimental and theoretical studies were conducted to analyze the vertical temperature profile and longitudinal temperature attenuation beneath a curved ceiling of a semicircular tunnel, and an engineering model for the gas temperature attenuation was established. The model predictions showed good agreement with literature and could predict measured data with relative error within 20%, applicable to fire protection engineering in semicircular tunnels.