Numerical Simulation And Experimental Research On External Flow Field Of Abrasive Water Suspension Jet

Abrasive water suspension jet(AWSJ)processing technology has many advantages,such as no heat effect,high processing quality and little influence on mechanical properties of processed materials.It is widely used in aerospace,mechanical manufacturing,medical and health fields.However,the processing accuracy is affected by the jet structure diffusion,the movement and spatial distribution of abrasive particles n the free jet region.Therefore,the velocity and spatial distribution of jet and abrasive particles in the free jet area outside the nozzle of abrasive water suspension jet are studied by numerical simulation and experiment.In this paper,LES turbulence model,VOF multiphase flow model and DEM discrete element model are coupled to simulate the flow field of abrasive water suspension jet.The velocity and spatial distribution of jet and abrasive particles in the free jet region are studied,and the effects of different jet parameters(jet pressure,target distance)on the velocity and distribution of jet and particles are analyzed.Then,the high-speed dynamic capture experiment of abrasive water suspension jet was carried out to verify the reliability of numerical simulation of jet structure,and the abrasive jet lash experiment was carried out to verify the reliability of numerical simulation of particle motion combined with the theoretical formula of particle impact crater depth derived from elastic collision theory.Finally,the comparative experimental study of the abrasive water suspension jet and the abrasive slurry jet was carried out on the jet injection test bench.Through the above research,the following main conclusions are drawn:(1)The LES turbulence model,VOF multiphase flow model and DEM discrete element model are used to simulate the flow field of abrasive water suspension jet.The high-speed dynamic capture experiment and abrasive jet experiment verify that the numerical simulation is reliable and the maximum error is less than 7%.(2)The volume fraction of water at the nozzle axis decreases gradually with the increase of jet distance,and droplets peel off,break up and atomize on the jet surface.The jet velocity increases with the increase of pressure and decreases with the increase of injection distance.The length of the jet core zone is independent of the jet pressure and fluctuates around 20 mm.(3)The diffuse of abrasive particles are affected by the jet divergence,and the particles gradually diffuse with the increase of jet distance.In the free jet region outside the nozzle,the abrasive particles have inertia,and their velocity increases first and then decreases with the increase of jet distance,and there exist maximum particle velocity.(4)Polymer additives can improve the stability of the jet.The velocity of abrasive particles in abrasive slurry jet do not diverge obviously,and the particles are concentrated in the nozzle axis area.The particle velocity increases gradually to the maximum with the increase of the jet distance.In this paper,the jet structure and the movement and spatial distribution of abrasive particles in the free jet area outside the abrasive water suspension jet nozzle are obtained,which can guide the processing of abrasive water suspension jet and improve its processing accuracy and efficiency.