Abstract: Fires under high wind speed conditions are difficult to control and tend to cause more severe losses, but there is relatively little research on such fire scenarios. In this paper, combustion experiments of small-scale n-heptane square pool fires with a side length of 8 cm were carried out behind an obstacle under high wind speed conditions ranging from 10 m/s to 25 m/s in a combustion wind tunnel, and comparisons were made with scenarios of medium and low wind speeds from 1 m/s to 10 m/s. The results show that under medium and low wind speeds, the burning rate increases rapidly with the rise of wind speed in the initial stage, followed by a gradual decrease in the growth rate. When the wind speed exceeds 10 m/s, the burning rate exhibits a relatively stable linear growth with the increase of wind speed. The flame shape presents an arched form under low wind speeds; when the wind speed exceeds 10 m/s, the flame shape gradually transforms into an upward convex arc shape. Corresponding flame lengths and inclination angles were defined according to the different flame shapes under medium-low and high wind speeds. The total flame length decreases with the increase of wind speed, and the rate of decrease accelerates when the wind speed is higher than 10 m/s. The inclination angle of the lower flame segment increases with the rise of wind speed; while the inclination angle of the upper flame segment increases with wind speed under medium and low wind conditions, but decreases with wind speed under high wind conditions. Finally, empirical prediction formulas for the burning rate, flame length and inclination angle of small-scale n-heptane pool fires varying with wind speed were established respectively. The research results can provide theoretical support for fire prevention and control under high wind speed conditions.

Key words: high wind speed, n-heptane pool fire, obstacle, flame parameters, burning rate