Study On The Interaction Between Transient Flame And Wall

In confined spaces,such as engine combustion chambers,flame slamming often occurs and the process is unavoidable.The interaction between the flame and the wall has a critical influence on the evaporation and mixing of the fuel,and the diffusion of the flame,which will further affect the combustion process and the discharge process of the engine combustion chamber.At present,with the continuous development of advanced combustion technology of the engine,the wet wall phenomenon is also inevitable in the engine combustion chamber.Compared with the interaction between the flame and the wall,the interaction between the flame and the wet wall is also worthy of attention.In order to understand the interaction between flame and dry and wet wall,this paper studied the interaction between methane transient flame and dry and wet wall by high-speed schlieren method and self-illumination imaging method.First,the high-speed schlieren method was used to record and analyze the flame morphology development process and the influencing factors during the interaction between the methane transient flame and the wet and dry walls.The influence of flame extension radius and flame thickness during the interaction between flame and wall is mainly explored.It was found that the wall height,fuel flow rate,and wall wet and dry conditions all have certain effects on the flame extension radius and flame thickness during the flame-wall interaction process.Afterwards,the self-luminous and OH~* radical self-luminous conditions of the flame were photographed using an ICCD camera.The wall height,fuel flow rate and dry and wet conditions of the wall were used to investigate the self-luminous brightness and OH~* distribution during the interaction between the methane transient flame and the wall surface.The results show that:(1)The self-illumination intensity of the flame is affected by the wall height,the fuel flow rate and wall conditions.When the wall height is increased,the flame self-illumination brightness is significantly reduced during the interaction between the flame and the wall surface,and the bright portion of the flame is reduced and moved toward the wall surface.When the flow rate changes,the self-illumination brightness increases and moves downward.Changes in the dry and wet conditions of the wall also affect the self-illuminating brightness of the flame.Compared with the dry wall surface,the flame brightness has a significant improvement under wet wall conditions,and different wet wall conditions have different effects on the flame self-illumination brightness.(2)The distribution of OH~* radicals is affected by wall height,fuel flow rate and wall wet and dry conditions.As the wall height increases,the peak of OH radicals moves toward the wall.At the flame front,the fuel burns sufficiently,the degree of combustion is higher,and the OH~* radicals are more distributed.The increase in the flow rate enables the OH~* radical distribution to move toward the wall surface while the concentration increases.The effect of dry and wet conditions on the distribution of OH~* radicals is mainly reflected in the distribution of near-wall regions,and the thickness and type of oil film also have an effect on the distribution of OH~*.Finally,the flame quenching distance was investigated when the flame interacted with the wall under different wall heights,fuel flow rates and wall conditions.It is found that the flame quenching distance is affected by the wall height and other factors.The flame quenching distance is positively correlated with the fuel flow rate.Wall conditions have an effect on flame quenching distance.The difference in oil film thickness also affects the flame quenching distance,but the effect of different oil film types in the same thickness is close.