Numerical study of the fire-smoke temperature law in the shaft of a high-rise building under the chimney effect in winter

Abstract

Shaft structures in high-rise buildings may increase fire coverage due to chimney effects. However, few previous studies have considered the motion of the flue gas under the combined effect of the chimney effect and thermal buoyancy. So, we set a continuous gradient differential pressure opening based on the characteristics of the chimney effect in winter. The CFD method is used to simulate 12 operating conditions with different fire source locations and rates of heat release from the ignition source. We compare and analyze the temperature rise, the flue gas rise law and the variation of the thermal pressure difference between the inner and outer shafts for different fire source powers. The results show that, in the case of low-floor fires, the range of temperature appreciation and fluctuation at the local measurement point increases with the fire power and the distribution of temperature appreciation decreases with the height. The relationship between the dimensionless time and the dimensionless height of the flue gas layer is exponential for different fire position conditions. The fire causes the neutral surface to shift, and below the original neutral surface, the higher the position of the fire source, the more pronounced the shift of the neutral surface.

KEYWORDS:

• Chimney effect
• numerical simulation
• shaft
• flue gas movement
• neutral surface

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was funded by the General Program of Natural Science Foundation of Hebei Province of China [grant number E2022210069]; the National Natural Science Foundation of China [grant number 11802186]; the innovation research group project of the Natural Science Foundation of the Hebei Province of China [grant number E2022210078]; the Science and Technology Winter Olympics Special Project [grant number 21475402D]; the High-End Talents Project of the Hebei Province of China [grant number (2019) 63].