The effect velocity and direction of swirling air flow on the formation spray downstream of pressure swirl nozzle

Abstract

One of the methods for generation a finely dispersed spray for pilot nozzles, used in modern aircraft engines widely, is co-rotating or counter-rotating directed relative to the direction of movement of the fuel film, air flow swirl. Therefore, it is interesting to investigate the shape of the liquid film and its disintegration at low fuel consumption. In the present work, the influence of the speed and direction of the air flow on the main characteristics determining the dispersion and shape of the spray pattern downstream the pressure swirl nozzle was investigated. The mathematical model of the film motion in a curvilinear coordinate system associated with the film surface to obtain the basic characteristics of the spray was used. The main attention was paid to the spraying characteristics in the initial phase of the formation of the spray at the calculations carried out according to this model. Calculations showed that the swirling air flow helps to open the entire cone spray angle, however, the initial angle of the spray is smaller than in the absence of air flow near the nozzle with opposite swirling,. The work also showed that swirling air flow reduces the thickness of the fuel film in the immediate vicinity of the nozzle almost the same, regardless of the direction of its rotation. The effect of the swirling air flow on the average sizes of atomized fuel droplets based on the calculation of the thickness of the fuel film, its speed and the cone angle of the spray data were obtained. The results are compared with the available experimental date.