Research On Multi-Objective Optimization For The Self-Excited Oscillating Pulse Cavitation Jet Nozzle

Self-oscillating nozzles are the core parts of water jet drilling machines,cleaning and derusting machines and other equipment,which have the advantages of large impact force,long range,jet not easy to diverge and high reliability,and have been widely used in military and civil industrial production fields.However,the pulsed cavitation jet can only be generated by the self-excited oscillating nozzles under specific structure and state parameters,and the mechanism of the emergence and evolution of the pulsed cavitation jet phenomenon is very complex,and the related issues need to be further explored and studied.Therefore,based on single/double cavity self-excited oscillation pulsed cavitation jet nozzle as the research object,the numerical simulation and flow visualization experiment technology of combining the method of flow field inside its evolution features and the multi-objective optimization problem research,in order to reveal the resonance mechanism,explore the influence of parameters on jet performance,determine the optimal structure and state parameter matching scheme.Established the self-excited oscillation pulsed cavitation jet nozzle geometric model,considering the internal nozzle flow field characteristics,the nozzle structure parameters and the key influencing factors,such as fluid motion parameters determine the Mixture multiphase flow model,Realize k-ε turbulence model,Schnerr and Saue cavitation model and a numerical simulation of elements such as grid partitioning strategy,and established a single/double cavity self-excited oscillation pulsed cavitation jet nozzle simulation model.Study on jet characteristics of single-cavity self-excited oscillating pulse cavitation jet nozzles.The evolution characteristics of the inner and outer flow field of the single-cavity nozzle were analyzed,and the resonant mechanism was revealed.The influences of the inlet fillet,cavity diameter,cavity length,lower nozzle diameter and inlet pressure on the jet performance of the single-cavity nozzle were discussed.Study on jet characteristics of cavitation nozzles with double cavity self-excited oscillation pulse.Analyzes the features of double cavity flow field inside the nozzle evolution,reveals its resonance mechanism,analyzed the double cavity cavity diameter nozzle cavity entrance rounded corners,before the cavity,cavity length and cavity before the cavity under the nozzle diameter,cavity,the cavity cavity after entry the rounded,cavity diameter,cavity after cavity length and cavity after the nozzle diameter and the influence law of parameters such as inlet pressure on the jet performance.Multi-objective Optimization of Self-excited Oscillating Pulse Cavitation Jet Nozzle.Based on the nonlinear mapping property of neural network algorithm and the global optimization property of non-dominated sorting genetic algorithm,a collaborative optimization algorithm combining neural network and genetic algorithm was constructed,and the solution set of the optimal parameter matching scheme of single/double cavity self-excited oscillating pulse cavitation jet nozzles was determined.Experimental study on visualization of flow field of self-excited oscillating pulse cavitation jet nozzles.Based on the optimal solution set of parameters determined by multi-objective optimization,a fully transparent test model of single-cavity/double-cavity self-excited oscillation pulse cavitation jet nozzle was fabricated by 3D printing technology.The development and evolution process of the cavitation vortex in the nozzle cavity and the state of the outflow field were recorded by a camera,and the correctness of the optimization results was verified.