Study On The Factors Influencing The Flashover Of Ancient Wood Structure Building

China’s ancient wooden structure carrying the wisdom of the ancient working people,representing the traditional Chinese culture,but because of its structure and selection characteristics,vulnerable to fire damage,and the corresponding protection and preventive measures lack the theoretical basis,Therefore,it is of great practical significance to the fire prevention of ancient buildings and the selection of future numerical calculation parameters.In this paper,based on the law of the phenomenon of flashover as a mutation,think of the regional heat release rate begins to show a continuous,approximately linear mutation as the beginning of a flashover.In view of the characteristics of ancient architecture in China,a Ming Dynasty Taoist ancient architecture as a prototype,the building is the form of the roof double eaves hanging Hill,the main support structure for the wood,maintenance structure by the brick masonry.Based on the advantages of FDS in fire numerical simulation,the effects of fire and ventilation factors on the flashover of the building are studied,and for different fire source area,fire power,the location of the fire,the location of the vents,and the opening h o u r s o f t h e f l o o r s o f t h e w o r k i n g c o n d i t i o n s w e r e c a l c u l a t e d a n d a n a l y z e d.The results show:In the fire source factor:(1)The fire source area and the flashover time was positively correlated.(2)Fire power and flashover time in a certain range of monotonically decreasing power function relationship,and when the fire power is small,the working conditions of the flashover time difference is very small.(3)The range of combustion varies with the location of the fire.When the fire source is located outside the atrium,the first layer is the main combustion zone,the maximum heat release rate QMAX≈7.9×104 kW.When the fire source is located inside the atrium,the second floor is the main combustion zone,the maximum heat release rate QMAX≈6.2×104 kW.In terms of ventilation factors: Ventilation position and area changes,resulting in differences in indoor oxygen content,so the firing intensity,the spread of the range was significantly different,but the flashover time is about 400 s.At the same time the first floor or second floor of the opening time and the flashover time between the significant correlation:(1)When the opening time of the second floor t ≤ 350 s,the flashover time is negatively correlated with the opening time of the vent,the maximum heat release rate is QMAX≈6.2×104k W.And the opening time of 400 s ≤ t ≤ 600 s,the opening of the vent will lead to flashover,the maximum heat release rate increases with the opening time lag;(2)When the opening time of the first floor t ≤ 400 s,the flashover time is negatively correlated with the opening time of the vent,the maximum heat release rate is QMAX≈6.2×104 k W.And theopening time of 450 s ≤ t ≤ 600 s,the opening of the vent will lead to flashover,the maximum heat release rate increases with the opening time lag.