Research On Atomization Performance And Structure Optimization Of Pressure Swirl Nozzle

With rapid development of the industry,the problem of fire safety is becoming more serious.Fires can cause serious economic losses and threaten lives.Therefore,fire-fighting technology occupies a very important position and is widely used in computer rooms,archives and other occasions.Nozzle is a major component in the fire extinguishing system,and the fire extinguishing effect is decided by the quality of the atomization performance.Pressure swirl nozzles are often used in life,they have simple structure and good atomization quality,and play an important role in the fields of fire protection and chemical industry.The paper took pressure swirl nozzle as the research object,started from the mechanism,studied the atomization mechanism of the pressure swirl nozzle and explored the effect of nozzle structure on atomization effect.The combination of experiment and numerical simulation was used.The structure of the pressure swirl nozzle was changed.The fluid flow state inside the nozzle and the atomization characteristics of external droplets were simulated and analyzed by the simulation software Fluent.The influence law of different pressure and structure parameters on axial velocity,atomization particle size,and atomization cone angle were obtained.Finally,a genetic algorithm was introduced to optimize the pressure and nozzle structure parameters based on the atomization particle size and the atomization cone angle to obtain a set of optimal values and verify them.The main research contents of the paper are:(1)Firstly,the mechanism of liquid atomization and fire extinguishing was explored.According to Bernoulli equation and momentum conservation equation,the parameter equations of pressure swirl nozzle discharge coefficient and atomization cone angle were established,and the influence of geometric characteristic parameter on the discharge coefficient and atomization cone angle was analyzed.(2)The pressure swirl nozzle atomization experiment platform was built,and the nozzle atomization experiment was carried out,and the lows of nozzle inlet pressure,nozzle outlet diameter and atomization cone angle were obtained.The atomization model of the pressure swirl nozzle was established,the mesh was divided,and the boundary conditions were set.Fluent software was adopted to simulate nozzle atomization process,and the results were compared with the experimental results.(3)Taking the nozzle inlet pressure,nozzle outlet diameter,and length of the swirl chamber as variables,the Box-Behnken experimental design was carried out by Minitab.The effect of pressure and nozzle structure parameters on the axial velocity of the droplet,the atomization particle size and the atomization cone angle were obtained.And use the multiple regression method to establish the mathematical regression model of the three variables and atomization particle size,atomization cone angle,and carry out variance analysis.(4)Introduce genetic algorithm.The optimization goal was to reduce the atomization particle size and increase the atomization cone angle.The NSGA-Ⅱ algorithm was used to optimize the pressure and structural parameters,and the optimal pressure and structural parameters were obtained.And the results were verified.