| As components of the combustion organization,fuel nozzle is often used in the combustion chamber of the engine.Its performance directly affects the specific impulse,stability and service life of the engine and other thermal power equipment.The swirl nozzles are often used in the complex working environment of various combustion equipment due to their good mechanical properties,simple structure,stable atomization effect and other advantages.The internal flow,liquid film breakup and spray field in the swirl nozzle are systematically analyzed with combining a particle dynamic analysis system and a high-speed photography system spray test experiment method and the numerical simulation method of the nozzle flow in this paper.The effect of different trumpet angles for the internal and external flow fields near the nozzle is studied,and the breakup characteristics of liquid film in the swirl nozzle under different injection condition and the spatial distribution of the spray field formed is obtained,which provides guidance of the structural design of the swirl nozzle.（1）Analysis of the internal and external flow characteristics of the swirl nozzle near the nozzle area.The internal flow of the nozzle trumpet angle in the swirl nozzle is simulated,and the influence of the opening degree and height of the nozzle trumpet angle on the liquid film flow under different pressure conditions is studied,and the internal flow of the nozzle with different angle structures and effect on external spray is revealed.With the increase in the opening degree of the nozzle trumpet angle,the tangential velocity of the liquid film of the nozzle model of group A decreases,the radial velocity increases,and the spray cone angle decreases of the increase in the trumpet angle;the tangential velocity of the liquid film of the nozzle model of group B decreases,but the radial velocity firstly decreases and then increases,the spray cone angle firstly decreases and then increases with the increase of the trumpet angle.With the decrease of the nozzle trumpet angle height,the radial velocity of the liquid film of the nozzle model increases,the tangential velocity stable,and the spray cone angle increases with the trumpet angle.（2）Research on the influence of pressure conditions on the liquid film breaking and atomization of centrifugal nozzles.The small-size swirl nozzle models with different numbers of swirl slot are designed and spray test experiments are carried out.The flow breakup characteristics and atomization performance of the liquid film with different numbers of swirl grooves and injection conditions are studied.When the injection pressure is in the range of 0-0.5MPa,the increasing pressure will increase the liquid film breakup length,breakup time and the velocity of droplets,reduce the SMD the spray field.The increasing the number of swirl slot will decrease the liquid film breakup length,the spray field concentration and spray angle,decrease the droplet velocity and SMD of the spray field,improve the uniformity of particle size.Based on the experimental data,the cone liquid film dispersion equation is solved,and the regulation of the growth rate of the liquid film surface wave of the two nozzles is obtained,and the reason for the decrease of the breakup length by the increase in the number of swirl grooves is explained from a theoretical perspective.（3）Research on the spray field distribution characteristics of the integrated atomization of double swirl nozzles.Experiments were carried out on the spray field distribution of the integrated spray by the installation distance between two nozzles of60 mm and 100 mm respectively,and the droplet size,concentration and velocity distribution characteristics of different areas of the spray field were obtained,and the collision effect of the droplets in the spray field was analyzed,and the regulation of influence on the spray field in the center area of the two nozzles.The increasing flow rate will decrease the average SMD of the transverse section and make average SMD stable of the longitudinal section.The axial velocity and the number of droplets colliding in the central area will increase from this influence.The increase of the nozzle spacing reduces the average SMD of the spray field,the axial velocity of the transverse section increases,and the axial velocity of the longitudinal section decreases.Combining the collision mechanism of the two droplets of the open platform,the collision,fusion and separation probability of droplets in the spray field under different flow rates are analyzed and the experimental results are compared and verified. |
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