Experimental Investigation On The Stability And Morphological Change Of The Methane/Hydrogen Non-premixed Jet Flame In Hot Coflow

Non-premixed jet flame is widely applied in the actual combustion equipment,which the flame stability affects the safe operation of combustion equipment,and the flame structure determines the size of combustion equipment.Generally,there is a hot coflow atmosphere in the combustion chamber.These characteristics have different changes in different conditions,so it has important theoretical significance and practical application value to study the stability and shape change of jet flame under different conditions.This paper experimentally studied the stability characteristics and the evolution of the geometry of methane/hydrogen jet diffusion flame.For this experiment,a heat coflow experiment system is designed and built,mainly including burner,gas system,heating system and data acquisition system.Through debugging and calibration,the accuracy of the experiment system is guaranteed,and the precisely control of temperature,coflow and the center jet was achieved.The flame image information is extracted by MATLAB software,which ensures the accuracy of the data obtained.Firstly,based on the established experimental platform,the experimental study on the flame stability of the laminar non premixed jet flame in hot coflow was carried out,and the effects of different coflow velocity and dilution on the flame stability under laminar flow conditions were studied.It is found that different coflow velocity and dilution can change the existing state of flame under laminar flow conditions.By analyzing the movement changes of the tip and base of the flame,the influence of coflow velocity and dilution on the flame stability of laminar non premixed jet is revealed.Secondly,the experimental study on the stability of turbulent non premixed jet flame under the condition of hot coflow was carried out.By changing the coflow speed,fuel ratio and diluent concentration,the changes of initial lifting speed,blowing out speed and lifting height of flame under different conditions were obtained.The causes of flame lifting and blowing out under different conditions were analyzed and discussed,and the influence of different initial conditions on the flame stability of turbulent non premixed jet flame is clarified.Finally,the dynamic change of flame is captured by high-speed camera.By analyzing the flame in different states,the law of flame shape change is studied,the correlation between the width and height of flame base is clarified,and the law of influence of different conditions on the change of flame length is also revealed.