An Experiment Investigation On Breakup And Atomization Mechanism Of A Swirling Liquid Jet

Swirl nozzle is widely used in gas turbines and in GDI engines and many other fields. The characteristics of the hollow swirling liquid jet form the swirl nozzle at its initial stage and the mechanism of atomization of the liquid jet have not yet been well understood. A further investigation is carried out experimentally on this problem.In order to verify the accuracy of theoretical prediction, an experimental system consisting of three parts, i.e. the injecting system, the photographing system, and measurement of liquid droplets, has been established. The swirl nozzle with swirling chamber and orifice is used to form hollow swirling liquid jet. The geometry of this type swirl nozzle can be conveniently changed.An experiment study on the hollow swirling liquid jet has also been conducted. The effect of flow conditions, fluid properties and nozzle geometry on the hollow swirling liquid jet in near field shape is also investigated. The results of the experimental work show that: increasing the pressure and the diameter of the orifice will increase the flex, and decreasing the angle of the swirling chamber and the diameter of the swirling chamber will decrease the flux; increasing the injection pressure will lead to the increase in the development of the hollow swirling liquid jet in free space. As the surface tension of the liquid is increased, the size of the liquid jet is reduced. The effect of orifice diameter on the size of the liquid jet is large and the effect of swirl chamber diameter is only small. With the increasing length diameter ratio of exit orifice, the decreasing the angle of the inlet, it will reduce the size of the shape of the jet. The existing of pressure difference between outer and inner surface of the jet constrains the development of the jet, resulting in the reduce of the size of the shapeThen we systemically study the disturbance wave on the shape and the relationship among the pressure, the liquid property and nozzle geometry. The results show that: increasing the injection pressure will lead to speeding up the breakup of the jet. As the surface tension of the liquid is increased, it is later to see the breakup of the jet. It will speed up the breakup of the jet as decreasing the diameter orifice and the length diameter ratio of exit orifice, increasing the angle of the inlet and the swirl chamber diameter. Through experimental study, the macro-characteristics of the breakup of the hollow swirling liquid jet have been investigated. The results show that: increasing the injection pressure, swirling chamber and the angle of the inlets will increase the angle of the jet; the material has nothing with the angle of the jet; increasing the pressure, the swirling chamber and the angle of the inlets will decrease the length of the jet, but it will not be zero; increasing the pressure and decreasing the diameter of the orifice will decease the liquid droplets by which we can get small droplets.