Simultaneous measurements of gas flow and flame front movement in a turbulent premixed flame zone

Abstract

Instantaneous local flame front movement and the flow velicity of unburned mixture or burned gas near the flame front in a turbulent flame zone have been measured simultaneously by using a micro-electrostatic probe with three sensors and a dual beam LDV system. The mean gas flow was also measured to explore the flow field of the turbulent premixed burner flame. It was found that there are evident differences in the velicity and direction between the mean gas flow and the most probable flame front movement at the side of the turbulent flame zone. The flow velocity of the burned gas near the flame front was found to be generally larger than that of the unburned mixture when the flame front moves toward the burned gas side, although no appreciable difference in their flow velocities is seen when it moves toward the unburned mixture side. Based on the relation between the flame front velocity and the flow velocity of the unburned mixture near the flame front, it was estimated that the local flame velocity is equal to the vector sum of the laminar burning velocity and the flow velocity of unburned mixture near the flame front. The relation between the overall flame front movement and the instantaneous local flame front movements was discussed using a simple model of a flame front movement.