Experimental Study On The Atomization Characteristics Of Power Law Liquid Jets Under High Ambient Pressure

Liquid jets are a widespread phenomenon in the nature and the engineering applications.The breakup and atomization of liquid jets are important in theoretical research and engineering application.Whether in life or in engineering application,a power law fluid has extensive application.Because of the complexity and variety of the non-Newtonian liquid,the theoretical explanation of the jet breakup and experimental understanding are still not satisfactory.Research for power law fluid jet broken not only helps to enrich non-Newtonian fluid mechanics and the theory of the liquid jet broken but also has important significance for engineering applications.In this paper,most experimental studies have been carried out on power-law fluid jet crushing under high ambient pressure with self-configured power-law fluid as experimental liquid.The high-speed photography system was used to obtain the spray pattern images of cylindrical power-law fluid jet and impinging jet,and the breakup characteristics such as breakup length and spray cone angle were extracted.Particle size distribution of droplets in a spray field was measured using a three-dimensional Phase Doppler System.The effects of jet parameters,ambient parameters,nozzle structure parameters and fluid physical parameters on atomization characteristics were studied in detail.The experimental results show the breakup length decreases with the increase of the ambient pressure,and the spray cone angle increases with the increase of the ambient pressure,which indicates that the ambient pressure plays an important role in promoting the jet fracture.Under the same injection pressure,ambient pressure and nozzle structure parameters,Sauter mean diameter(SMD)of the breakup droplets decreases gradually along the jet axis.At the same axial position of the jet,SMD can be regard symmetrical along the radial direction,and SMD is found much bigger at the edge of the jet.It is found form the experiments that SMD of the power-law liquid jet decreases with the increase of injection velocity,with the increase of back pressure,and with the decrease of nozzle diameter.The results also indicate that the viscosities of power-law liquid jet have great effects on the breakup of the jets.It can be said that the experimental results agree well with the results given by the instability analysis.For the symmetrical impact jet,the experimental results show that,with the increase of jet velocity,five types of breakup modes are found in open space and high ambient pressure.They are closed rim,open rim,rimless sheet,bow shaped ligament and fully developed.Jet velocity,ambient pressure,impact angle,nozzle structure,liquid properties and other parameters will have a greater impact on the breakup mode.Breakup mode will be a big difference and individual models do not even appear.The increase of the jet velocity,the ambient pressure and the angle of impact will promote the symmetry impingement jet breaking.The increase of the nozzle diameter and the power law fluid mass will inhibit the symmetry impinging jet breaking.