High-performance Swirl Combustion Device Pneumatic, And Atomization Characteristics

This paper investigates air blast device of liner dome which is the key technology used for aero-engine combustor. A calculating method on nozzle performance with a wide range of flow has been established, which considers the pressure loss of flow path. The effects of double-stage swirler parameters, Venturi tube parameters and aerodynamic parameters on downstream flowfield and spray performance have been analyzed. The structure of double swirler spray device and the optimum of fuel/air matching have been gained. By investigating the effect of nozzle spray on air blast performance, it is found that nozzle supply performance plays an important role in air blast.Taking CFM56-3 engine for an example, nozzle pressure (flow features and spray features) has been calculated. It can be seen that nozzle primary flowpath pressure—the increasing rate of flow curve is faster than the increasing rate of normal nozzle characteristics, so the range of supply is widen at the same pressure.The effects of characteristic parameters on flow and spray have been researched by changing characteristic parameters of swirler and Venturi tube. Results show that the effect of swirl number on flow coefficient is great, but the effect on flow area is weak. The first stage swirl plays an importmant role in fuel spray. The flow ratio between the first stage swirler and the second stage swirler has considerable influence on air blast. The size of recirculation flow region is determined by the second stage swirler number and air flow. It is associated with the match of dome parts. Construction of Venturi tube path and lip characteristics directly effect on air blast. Air blast performance of convergent flow path and Venturi tube with sharp lip is best. Throat diameter of Venturi tube has great influence on air blast. Increase in throat diameter is beneficial to air blast.Construction of Venturi tube path and lip characteristics directly effect on air blast. In this paper, flowpath is convergent and the diameter of throat isφ20. The performance of Venturi tube with sharp lip is best. By researching the effect of the first spray on air blast, it can be found that the effect of the high quality first spray on spray performance is not significant under all kinds of operating condition. Through bringing down the quality of the first spray, it is beneficial to air blast performance at high operating conditions, at the same time the size of drop is more equal. But at lower operating conditions, the quality of the first spray should be improved to meet the lowest requirements.Characteristics of downstream flowfield and recirculation region and air blast performance of double-stage swirler dome have been calculated. The calculating results show that the size of recirculation region is proportional to the second stage swirler number. The front station point of downstream recirculation region is drawn back as reduce of Venturi tube throat diameter. It is beneficial to anti-carbon deposit, but it is not beneficial to air blast. All the factors should be considered in design.Comprehensively considering the aerodynamic and spray performance of double-stage swirler and Venturi tube, A-B-C combination structure in this paper is the optimum structure. It should be the best selection in combustor design.