Study On Combustion Characteristics Of Diffusion Flame Under Cross Wind

The traditional static fire source diffusion flame is mainly affected by the buoyancy caused by the vertical density difference,the diffuse flame in the cross wind is also subjected to a horizontal force,making the flame profile tilted,shaking,tearing or even flying,causing the transient combustion characteristics of the diffused flame to become more complicated.Study on the characteristics of diffusion flame structure under transverse wind,which has practical engineering application value and theoretical guidance significance to forecast,prevent and rescue fire,and it is helpful to enrich and perfect the theoretical system of diffuse flame combustion.In this paper,the flame image sequence under the influence of cross wind is obtained by using the linear motion diffusion fire test-bed and the diffuse flame wind tunnel experiment system.Then,the temperature range of the flame and the turbulence pulsation frequency and the combustion efficiency are calculated by MATLAB digital image processing technology.Combustion characteristics and mechanism of diffusion flame under crossing wind.These work are used to reveal the combustion characteristics and mechanism of diffused flame under crossing wind.Taking the linear motion diffusion flame of Bunsen light as the object,the transient motion image sequence of the flame under different acceleration was obtained by the linear motion fire source test bed.The flame two-dimensional temperature field reconstruction and the flame area were calculated by image processing technology,thus obtained was processed and used to study the change in the flame area and specific floor area of the flame over different temperature ranges,at the same time,the combustion process of the diffusion flame is divided into three stages by using the momentum flux ratio R of the crosswind velocity and the exit velocity.The results indicate that: In the fuel control stage with smaller wind speed,the total area of the flame increases with the increase of the moving speed,the low-temperature and specific floor areas adopt more dominant positions;the total area of the flame in the transition zone is drastically reduced,but the temperature of most of the area of the flame in this area changes from low temperature to high temperature;while in the high-speed cross-flow wind control zone,the area of the high-temperature zone and specific floor area take the dominant positions.The crossflow wind increases the high-temperature specific floor area of the fire compared to that of a stationary fire,the consumption in the moving fire also becomes correspondingly more concentrated and fierce.Based on the diffuse flame wind tunnel experiment system,the color image sequence of the oil tank flames under the action of traverse wind is obtained,through MATLAB scripts calculate the fluctuation frequency of the flame under static conditions and the fluctuation frequency of the upper edge of the flame plume under the action of the wind.The results indicate that: the fluctuation frequency of the oil pan flames under the static condition satisfies the formula f ^ 2 ?1.28/D.The dimension St = 2.31(Fr)^(-0.529)is obtained by dimensionless analysis and calculation.In the experimental wind speed range,the pulsating frequency of the flame increases first and then increases with the increase of wind speed.The combustion efficiency of the flue gas was calculated by the flue gas analyzer.The results showed that the overall trend of the flammability efficiency of the flue gas increased first and then decreased with the increase of the transverse wind speed.During the mixing phase,the combustion efficiency is not less than 95%.The work of this paper has a more comprehensive understanding and research on the combustion characteristics of diffused flame under the action of traversing wind.