| When the high pressure water jet technology is used in the pilot production of Bayan Obo rare earth mine,the energy conversion efficiency of the conical straight nozzle is only 46%.As the core part of water jet system,the nozzle plays an important role in the effect of mineral crushing.Aiming at the problem of low energy conversion efficiency of water jet nozzle,the method of combining theoretical analysis and numerical simulation is adopted,that is,based on the three equations of hydrodynamics,Bernoulli equation and finite element method,orthogonal experiment is designed to optimize the structural parameters of the nozzle Turn.The twodimensional and three-dimensional models of nozzle are established by AutoCAD and nxug software,and the mesh model of nozzle is established by ANSYS ICEM.Finally,the flow field and jet characteristics inside and outside the nozzle are simulated by ANSYS FLUENT software.First of all,six streamline curves are selected from many function curves as the contour curves of the transition section of the high-pressure water jet mineral crushing nozzle.The static pressure,velocity and turbulent cloud diagrams of the conical straight and six different contour nozzles are obtained by using the simulation software,so as to analyze the jet characteristics of the nozzle and calculate its energy conversion efficiency.Through comparative analysis,the Gauss curve nozzle has the characteristics of high flow velocity,low pressure and low turbulence energy.The average velocity is 255.85m/s,and its energy conversion efficiency is 83.65%.In order to further improve the comprehensive performance of the Gaussian curve nozzle,the orthogonal test method is used to optimize the inlet,contraction and outlet segments of the nozzle.The results show that the length of the contraction segment of the nozzle has the most obvious effect on the jet flow.The Gaussian nozzle with the length of the inlet cylindrical segment of 5mm,the length of the contraction segment of 50 mm and the length of the outlet cylindrical segment of 12.5mm has the fastest average velocity and the smallest gradient of the outlet velocity Before optimization,the average velocity of the nozzle is increased by nearly 1 m / s,and the efficiency is increased by 0.6%.Finally,in order to improve the efficiency of the nozzle in crushing minerals,a kind of porous nozzle with high working efficiency is designed based on the single hole nozzle.The orthogonal test method is used to optimize the number of holes,the distance between holes and the inlet pressure of the Gauss nozzle.After analyzing the optimization results,it is concluded that the inlet pressure of the nozzle has the most significant effect on the jet,but the inlet pressure is not the greater the better,but in a certain degree The most suitable pressure is selected in the range;the number of holes is 4 and the distance between holes is 2.5mm,and the average velocity of outlet of 7 porous nozzle reaches 242.26m/s under the inlet pressure of 60 MPa,which has higher energy conversion rate,good jet clustering and better comprehensive performance.The final results show that using the function curve as the flow path curve of the highpressure water jet nozzle and orthogonal optimization of the structural parameters of the nozzle can significantly improve the energy conversion efficiency,jet clustering and pulverizing effect of the nozzle,which has a certain guiding effect on the actual production. |
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