| In this paper,the atomization characteristics of fan nozzles used in integrated afterburners under both atmospheric and afterburner environments are experimentally studied.The main characteristic of integrated afterburners is the integrated design of the rectifier branch plate of turbine frame and flame stabilizer of afterburner.In the regurgitation zone formed by the back concave structure of the stabilizer,ignition is carried out and stable flame is formed.Therefore,the atomization performance of nozzle has a great influence on distribution of fuel atomization in the concave chamber of an integrated afterburner,which directly determines the ignition performance and the flame stability in regurgitation zone of the concave chamber.Fan nozzle has a unique advantage of uniform distribution of fuel in a certain plane,which makes it suitable to be used in the concave cavity of integrated afterburners.The research contents of this paper are mainly divided into the following three aspects:Firstly,aiming at improving the shortcomings of direct injection nozzles for afterburner,a kind of fan nozzle for afterburner is designed.The structure parameters affecting the atomization characteristics of the fan nozzle are put forward.In addition,the flow characteristics of the designed fan nozzle are tested and the effects of different fuel supply pressures and structure parameters on its flow characteristics are studied.The test results show that:(1)The diameter of the accumulating chamber has a great influence on the flow coefficient of fan nozzle.Besides,while the height and angle of the fan outlet have a certain influence on flow coefficient of fan nozzle,the position of the fan outlet has little influence on flow coefficient.(2)The flow coefficient of same fan nozzle decreases gradually with the increase of oil supply pressure,and finally tends to be stable.Secondly,an experimental study on atomization characteristics of fan nozzle in atmospheric environment is carried out.The nozzle atomization angles,particle size distributions and velocity distributions of different fan nozzles under different fuel supply pressures are measured by high-speed camera,Malvern particle size analyzer and particle image velocimeter respectively.The test results show that:(1)The outlet angle of fan nozzle is the only structural parameter determining the atomization angle while other structural parameters have little effect on atomization angle.(2)The diameter of the effusion chamber and the height of the fan outlet affect the diameter of the oil droplets by influencing the area of the outlet,while the position of the fan outlet has little effect on the average SMD of the oil droplets.(3)The oil droplets with larger velocity are mainly distributed in the middle of the fan-shaped spray field when oil supply pressure is low.With the increase of oil supply pressure,the oil droplets with larger velocity gradually expand to both edges of the fan-shaped spray field.(4)The diameter of the effusion chamber has the greatest influence on the velocity field of the oil droplets injected from fan nozzle.The angle of the fan outlet and the height of the fan outlet have some influence on the velocity field of the oil droplets from the fan nozzle while the position of the fan outlet has no obvious influence on the velocity field.Thirdly,the atomization characteristics of fan nozzles are studied under the afterburner environment.The fuel jet atomization processes of fan nozzle under different air inlet conditions and fuel supply pressure are tested using a high-speed camera.The experimental results show that:(1)The inlet temperature of the transverse flow has the greatest influence on the spray field.With the increase of transverse flow temperature,the spray field is closer to downstream,penetration depth is shallower,and the particle size is smaller.(2)In transverse flow,droplet size in downstream and at gas-liquid interface is smaller,and the gradient of droplet size change on windward side of the spray field is larger than that on leeward side.(3)The larger the oil pressure,the deeper the outer boundary of penetration path,and the smaller the droplet size.(4)With the increase of inlet air velocity,the penetration path of jet flow become shallower and the spray field is closer to downstream.While inlet velocity has a certain influence on particle size of downstream area,it has little influence on that near the outlet area.(5)The smaller the diameter of the effusion chamber is,the more dense the spray field is and the deeper the penetration depth is.The results obtained above can provide technical support for the design and optimization of afterburning fan nozzles. |
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