Experimental Study Of The Stability Of Co-flow Laminar Difussion Flames

In recent years,the destruction of the environment caused by the large-scale use of fossil fuels has attracted more and more attention.The productions of fuel combustion,such as soot,polycyclic aromatic hydrocarbons(PAH)and NOX,are polluted to the atmosphere and seriously threaten human health.Soot particles are the primary cause of haze weather in northern China.In order to reduce soot emissions,it is necessary to study the soot formation mechanism and flame combustion characteristics.The flame characteristics of fuel combustion at elevated pressure have always been a hot topic of research.The burning of liquid fuel at elevated pressure conditions is very likely to cause flame instability and hinder the progress of subsequent experiments.In addition,for industrial combustion devices,maintaining stable flame combustion can reduce damage to parts and components and reduce potential safety hazards.In order to explore the influence of various factors at elevated pressure on the stability of liquid fuel flame,this paper uses gas fuel methane and liquid fuel nheptane as experimental fuels,and obtains the Co-flow laminar diffusion flame image of fuel under different working conditions through ICCD camera.Image processing methods were used to analyze the effect of pressure,co-flow air and fuel flow rate,the initial temperature of fuel on flame stability.Experimental analysis shows that as the pressure increases,the degree of flame instability increases;As the flow rate of co-flow air and fuel increases,the flame tends to be stable,and the flame stability is best when the speeds of the two are similar;The flame tends to be stable at elevated fuel initial temperature.In addition,the thesis also explores the effect of the burner structure—the shape of the honeycomb of co-flow air outlet and the diameter of the nozzle on the flame stability.The results show that the flame is most stable when the honeycomb shape of the co-flow air outlet is evenly distributed,and the flame stability is better than that of the larger diameter when the nozzle diameter is smaller.Increasing the flow rate of Co-flow air and the initial temperature of the fuel in Co-flow laminar diffusion flame can help improve the flame stability,while other factors can decrease the flame stability.The paper explores the effects of various factors on flame stability,and the relevant conclusions provide a basis for the stable combustion parameter setting of liquid fuels.