Fire spreading characteristics and prevention and control of courtyard-type ancient buildings

• In the process of fire development, the horizontal spreading speed of flame is faster than the vertical spreading speed of flame, and the horizontal spreading of flame is the direct cause of the house flashing. • The heat radiation received by the front and side facades of the fire building is positively correlated with the openness of the burning room. • Under controlled ventilation conditions, the flashover time in a fully open room is 80 s faster than that in a closed room. • After the fire, the high-temperature high-speed air flow is mainly concentrated in the combustion chamber and the atrium, so the atrium is not suitable as a temporary shelter. • After the fire, all buildings will be flashover within 5–10 min, and all firefighting measures and rescue operations must be completed before this time. The courtyard-type ancient buildings have complex layout and large flow of people, after the fire, the spread path is complicated and the heat transfer form is diverse. This study takes a courtyard-type ancient building complex as the research object to explore the impact of ventilation conditions on fire smoke spread, temperature field, concentration field, and velocity field. Research has shown that the spread pattern of fire smoke is as follows: near the fire source − longitudinal spread of the wall − horizontal spread of the roof − vertical settlement − spread along the eaves and corridors − building fires; when a fire occurs, the high-temperature airflow under various working conditions is mainly in the burning room and atrium, so the atrium is not suitable as a temporary shelter; the lateral spread of flames is the direct cause of flashover in buildings. The time for flashover to occur within a building is generally 5–10 min. Open rooms have a faster occurrence of flashover than closed rooms, but closed rooms have a higher risk of fire; the heat radiation received by the front and side facades of the burning building is positively correlated with the opening degree of the fire room. Finally, suggestions for fire prevention and personnel evacuation of courtyard-type ancient architectural complexes were proposed from both technical and management perspectives. The research results can provide scientific and effective theoretical basis for fire prediction and optimization of evacuation plans for the courtyard-type ancient architectural complex.