Investigation On Combustion Characteristics Of Parallel Flame In Micro Gas Turbine Combustor Based On OH-PLIF Technology

Gas turbine technology has been praised as the crown of the industry,in which the combustion chamber is a key component of the gas turbine,the design of the combustion chamber structure will directly affect the overall combustion performance and operating efficiency.Micro gas turbine has gradually attracted more attention due to its compact structure,smaller volume,wide application scenarios and other advantages.Smaller volume also means smaller combustion chamber.How to organize combustion with high combustion efficiency,reasonable temperature distribution and strong stability in a smaller combustion chamber has become a key work.Based on micro gas turbine combustor design for three parallel flame burner nozzle,through the OH-PLIF flame diagnostic technique and numerical simulation technology in the different flow parameters and the different flame numbers of structural characteristics and combustion characteristics are studied,and put forward the drawing number and extension number representation flame more open to the flame and flame primary zone expanded,the influence of flame structure interaction dimensionless parameter characterization of flame and flame structure change influence much.After analyzing the experimental and numerical simulation results,it is found that:(1)With the increase of equivalence ratio,the main combustion zone of the flame gradually expands to the outer front,the height of the outer front gradually increases,and the maximum temperature and NO_x emission gradually increase;When the equivalence ratio is less than 1,the height of the inner front almost does not change with the equivalence ratio.When the equivalence ratio is greater than 1,the height of the inner front increases rapidly with the increase of the equivalence ratio.(2)With the increase of Reynolds number,the main combustion zone of the flame gradually expands to the outer front,the height of the inner and outer front gradually increases,and the NO_xemission gradually increases;For single flame,the maximum temperature first decreases and then increases,while for double flame and triple flame,the maximum temperature first increases and then decreases.(3)with the increase of number of flame,primary zone due to the interaction between flame makes flame acceleration front outward extension,flame overall development towards opening phenomena,frontal height,the highest temperature,NO_xemissions increase,frontal height within almost no effect when equivalent ratio less than 1,when the equivalent ratio is greater than 1 can significantly increase in frontal height.(4)Compared with the single flame,the temperature rise T_u of double flame and triple flame can reach the maximum value when the equivalence ratio is 0.8 and the Reynolds number is 1000～1500.When the equivalence ratio is less than 1,the effect of three-flame temperature rise is stronger than that of double-flame,and when the equivalence ratio is greater than 1,the effect of three-flame temperature rise is weaker than that of double-flame.The temperature rise effect of double flame is stronger than that of triple flame at different Reynolds number.(5)The NOx emission increases with the increase of equivalence ratio and Reynolds number,and tends to decrease when the equivalence ratio and Reynolds number are large.When equivalence ratio and Reynolds number are large,the existence of multi-flame will hopefully reduce NO emission.When the equivalence ratio is greater than 1.2 and the Reynolds number is greater than 1700,the existence of multiple flames can reduce NO2 emission.(6)In the experiment,the main reason for the opening at the top of the flame is the strong negative tension caused by the curvature at the top of the front in the flame,which leads to the rapid intensification of the flame diffusion effect at the top and the weakening of the combustion,thus causing the flame opening phenomenon;The weak forward stretching caused by the flow inhomogeneity mainly plays a dominant role in the position close to the nozzle.(7)At high equivalence ratio,the main combustion zone expansion effect of double flame is stronger than that of triple flame.At different Reynolds numbers,the main zone expansion effect of double flame is stronger than that of triple flame.(8)When the equivalence ratio is greater than 0.68,the dimensionless parameter I of flame structural interaction gradually increases with the increase of equivalence ratio;When the Reynolds number is greater than 728,the dimensionless parameter I of flame structural interaction gradually increases with the increase of the Reynolds number.