Abstract: In order to explore the influence of ambient wind speed on horizontal downstream fire spread of polyurethane foam, several groups of comparative experiments were carried out to analyze the influence of different lateral wind speeds on typical characteristic parameters of fire spread (flame shape, mass loss, near-field temperature and radiation). The experimental results showed that lateral wind speed can shorten the formation time of preheating angle of pyrolysis front, and the preheating angle is negatively correlated with wind speed. The reduction of preheating angle will increase the heat feedback area of flame front to preheating area and increase the fire spread speed. The flame front is affected by air entrainment under the direction of lateral wind speed stretching effect, and the melting dripping frequency increases during the fire spreading process, which increases the risk of secondary fire. At the same time, the mass loss rate of materials increases with the increase of wind speed in the process of fire spread. The cooling effect of wind speed is dominant in the early stage of fire spread, but it will still promote the fire spread speed, and the radiation peak difference between the up and low sides of the horizontal plate gradually increases.

Key words: ambient wind speed, Polyurethane foam, fire spread, combustion characteristic parameter, building fire