| High pressure water jet technology has been widely used for its high cleaning efficiency,energy saving and pollution-free features,so it is of great practical significance to use high pressure water jet technology to clear road marks and to study its cleaning characteristics and mechanism.In this paper,a detailed simulation and experimental study on the removal of road markings by high pressure water jet are carried out,and the removal mechanism of road markings by high pressure pure water jet and high pressure abrasive water jet is deeply analyzed.Through the Fluent simulation accurate analysis nozzle inside and outside the flow field condition.On this basis,the orthogonal test of LS-DYNA software is designed to simulate and carry out the road marking test.By comparing the simulation and test results,the optimal combination parameters of clearing road marking are obtained.Finally,the nozzle device is designed to improve the efficiency of removing road marks.Details are as follows:(1)Study on the mechanism of high pressure water jet cleaning line.The basic structure of high pressure water jet is analyzed,and the structural characteristics of the initial section,the basic section and the dissipating section of the jet are expounded.The cleaning mechanism of pure water jet and abrasive water jet was studied,and the principle of water jet removing road marking was further analyzed.Under the condition of green environmental protection and high recovery efficiency,the removal effect of road marking line is studied by using high pressure pure water jet and abrasive water jet with trace abrasives.(2)Simulation analysis of road marking nozzle to determine nozzle structure parameters.By Fluent software to simulate the internal and external flow field of nozzle by fluent software,and the pure water jet with a jet pressure of 100 MPa is selected to consider the effect of different inlet diameter,different shrinkage angle and different impact angle of the nozzle on the clearance effect of the marking line.Finally,nozzles with outlet diameter d=1 mm,inlet diameter D=5 mm,contraction Angleα=30° and length-diameter ratio l/d=3 are selected for the simulation and test of road marking clearance by water jet below.(3)Based on the study of LS-DYNA optimal clearance parameters to determine the main factors and order.The SPH-FEM coupling model of abrasive water jet clearance road marking line is established by LS-DYNA software.The parameters of abrasive water jet clearance road marking line are optimized and analyzed by orthogonal test method.The orthogonal test table of L9(33)is designed by orthogonal test method.The simulation results are analyzed by range analysis method.The results show that the primary and secondary order of the factors affecting clearance test is jet target distance,jet impact angle and jet transversal velocity.(4)Experimental study of road marking clearance to determine the best parameters for optimal clearance effect By preparing the test materials and test equipment,the test scheme is designed to study the effect of the test parameters such as jet pressure,jet target distance,jet velocity and jet impact angle on the clearance effect of road marking line.Halcon software was used to binarize the images of the test results,and the clearance rate of road markings under various influencing factors was calculated The results of research shows that the optimal road marking removal effect and efficiency can be obtained when the jet pressure is 20 MPa(containing micro-abrasive with a mass fraction of 0.27%),the jet target distance is 160 mm,the jet transverse velocity is 1500 mm/min and the jet impact angle is 30°.Finally,a column nozzle device composed of 5 nozzles is designed,LS-DYNA simulation and a single nozzle clearance area comparison,the results show that the design of the nozzle device has good practical value.Figure[43]table[10]reference[104]... |
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