Flame attachment effect on the distributions of flow, temperature and heat flux of inclined fire plume

The flame attachment behaviors over an inclined surface were investigated by a gas burner, and its effects on the temperature, heat flux, and the velocity distribution were explored by the heat flux meter, infrared thermography and particle image velocimetry (PIV) systems. The results showed that a sudden increase in flame attachment length occurred when the inclination angle of the surface increased from 15 to 20 degrees, which caused the sharp increase of the temperature, the heat flux as well as the flame spread parameter psi. Combined with PIV, it was found that a large velocity difference appeared between the upstream and downstream of the flame when the inclination angle increased from 15 to 20 degrees. The vortexes induced by the velocity difference moved upward periodically along the edge of the flame, increased the turbulence intensity and accelerated flame attachment greatly. By introducing the local Richardson number (Ri(x)) and the dimensionless local total heat flux, it was found that the plume was dominated by the momentum near the burner while dominated by the buoyancy in the distance. The turning point of the two regimes occurred at the ratio between the flame length to the burner hydraulic diameter of 0.5 and Ri(x) approximate to 10, and the local heat flux distribution of downstream fire was further obtained. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study on flame attachment over an inclined surface revealed that a sudden increase in flame attachment length occurred when the inclination angle of the surface increased to 20 degrees, leading to a sharp increase in temperature, heat flux, and flame spread parameter. Vortexes induced by velocity difference accelerated flame attachment, and local Richardson number and dimensionless local total heat flux were introduced to analyze the flame behavior.