Temperature Property of Ceiling Jet in an Inclined Tunnel

Abstract

The properties of a ceiling jet flow confined by the sidewall of an inclined ceiling differ from those of a flow in a horizontal tunnel and under an unconfined ceiling. However, few studies have focused on the flow property in an inclined tunnel. In this study, we conducted a series of fire tests using a 1/23.3-scale model tunnel with dimensions of 3.6 m (L) × 0.55 m (W) × 0.30 m (H) for various tunnel inclination angles of up to 20°. The model tunnel has a rectangular cross section and its aspect ratio is 1:2. Two types of fire heat release rates were used assuming vehicular fires in a passenger vehicle or a bus. The maximum temperature rise of the smoke layer near the ceiling and its position, Gaussian thermal thickness, and temperature properties from the plume impingement point along the steepest run in the upward direction were compared with the results obtained in a horizontal tunnel with longitudinal ventilation and an inclined unconfined ceiling.