Research On Low Pressure Atomization Characteristics Of Rotary Core Nozzle

In some medical service fields,a large number of clinical experiments have shown that the absorption speed and application range of drugs sprayed on human tissue after atomization are far superior to ordinary drug delivery methods.However,the level of domestic medical research is still relatively behind developed countries in foreign countries.For this reason,a micro-injection pump nozzle with an atomization pressure of about 7 bar has been designed for medical use,but there is no domestic market and the imitation effect is not good.Therefore,in view of the lack of research on the low-pressure atomization characteristics of nozzles,this paper took the rotating core nozzle as the main object under the atomization pressure of 0.1～0.6MPa,and combined theoretical knowledge,simulation and experimental testing to carry out research.The results were compared and analyzed,and the relevant conclusions about the characteristics of low-pressure atomization were drawn,which provided research ideas and reference value for the subsequent discussion of medical atomization methods.The atomization mechanism and the main characteristics of the atomization process were analyzed by using the relevant theories of spray science and fluid mechanics;Based on the working principle of the commonly used atomizing nozzles such as gas-assisted,rotary and pressure type,the atomization mechanism of the rotary core nozzle was discussed;The main evaluation criteria of the nozzle atomization characteristics and the important factors affecting the atomization effect were analyzed,which provided a theoretical basis for the follow-up research.Based on the governing equations of fluid mechanics,namely the three conservation laws,the three-dimensional modeling and simulation of the inner and outer water domains of the swirl nozzle were carried out by using the solution principles of the Realizable k-εturbulence model and the Pressure-swirl atomizer discrete phase model in the Fluent fluid simulation software.Based on the simulation results of the internal flow field,the effects of injection pressure,nozzle diameter and helical inclination on the velocity field were analyzed;From the simulation results of the external flow field,the effects of injection pressure and nozzle diameter on the particle size distribution,concentration and characteristic diameter of droplets were analyzed.The results showed that: under the atomization pressure of 0.1～0.6MPa,when the pressure increased,the radial velocity of the fluid jet was larger,the particle diameter of the atomization field was smaller,and the atomization angle was also larger;When the aperture increased,the greater the axial velocity of the outlet jet,the greater the flow rate of the fluid jet,and the wider the distribution range of droplets;When the inclination angle of the helix increased,the velocity of the fluid medium ejected was greater;The smaller the outlet length,the higher the radial velocity on the nozzle outlet face.An experimental platform was built,and the HX-6 high-speed camera,laser transmitter and computer were used to take pictures of the fog field of the nozzle under different injection pressures and outlet diameters.The droplet velocity,atomization angle and uniform distribution of three low-pressure nozzles in the fog field were mainly studied.The results showed that: under the atomization pressure of 0.1～0.6MPa,the shorter the outlet length of the cone-core single-hole nozzle,the wider the liquid spray range,the more uniform the droplet distribution and the finer the droplet;When the pressure and aperture increased,the higher the ejection velocity of the droplets,the more the number of droplets with irregular motion;Due to the influence of the external environment and the mutual rotation of eddy currents,the velocity of some droplets in the fog field cloud image increased locally and the direction was deflected;Under the same pressure,the atomization angle and the maximum velocity of the fog field of the rectangular groove nozzle with the same outlet diameter were greater than the atomization angle of the rotary core nozzle.Through the analysis of the internal and external flow fields of the rotating core nozzle,it was concluded that under 0.1～0.6MPa,the larger the velocity of the fluid medium in the rotating state,the larger the atomization range,the more uniform the atomization distribution,the finer the fog field droplets and the smaller the characteristic diameter;The shorter the length of the nozzle outlet section,the greater the speed of ejection,and the wider and more uniform distribution of the atomized droplets.This research not only has a deeper understanding of the low-pressure atomization characteristics of the nozzle,but also have important reference and theoretical value for the structural design of the new low-pressure atomizing nozzle and the research on the low-pressure atomization performance.