| The Jingjiang River located in middle reaches of the Yangtze starts from Zhi cheng to Chenglinji near the Dongting lake with a length of 347.2km.And it b e divided to upper and under by Ouchi mouth.Because of its natural characte ristics with the impact of the Three Gorges project,violent riverbed evolution an d frequent changes of marshland,which lead to unstable dredged channels and frequent hinder navigation.Tetrahedral framework has characteristics of water pe rmeable and waterblocking,now widely used in the middle reaches of the Yang tze River Waterway Regulation Project.Under complex flow conditions the fram ework is not clear how to achieve the optimal layout.The project framework h as been rarely studied at Spoiler fixing Mechanism;In addition,the existing proc essing technic of tetrahedral framework is lowlow-efficiency,ect.This paper reli es on provincial ministries study ‘Jingjiang River Channel Improvement Project Section VI' tenders construction technology research projects-projects 2".Combi ng the model test and numerical simulation,carried out wake field characteristic s through the tetrahedral,resistance characteristics,velocity distribution,which re vealed the spoiler reduction and fixing mechanism,and made a new process ab out tetrahedron cold extrusion frame connection,in ensuring the strength,greatly increasing productivity.Research contents and results include:(1)Experimental model study on turbulent flow and deceleration mechanism.Tetrahedral model test was carried out through the high-precision test kinetics sink river and DCMS control systems.Measure the tetrahedron Spatial distribution of the flow field under different conditions by comparison with frameless istribution;Obtain velocity distribution and specific deceleration,growth site around the tetrahedron;Reveal the disturbance when flow of water through the tetrahedron.(2)Numerical Simulation on turbulent flow and deceleration mechanism Based on past study of CFD,launched a two-dimensional,three-dimensional numerical simulation of permeable tetrahedron.The two-dimension studies get a change rule(wake vortex area variation)under different spacing ratio.Three-dimensional numerical simulations gained intuitive flow field variation around the tetrahedron,and with the results of model test comparison,verify the reliability of the numerical simulation.Finally,the spoiler effect analysis permeable framework combing with the existing sediment movement mechanics,revealed deceleration mechanism permeable frame-fixing;and on this basis,the proposed engineering applications spatial layout are designed.(3)Research on Tetrahedral framework cold steel casing extrusion molding technology to connect.In view of traditional process of limitations framework tetrahedral steel casing through cold extrusion forming new connection technologies are proposed.This technology optimizes the frame bar of the processing and splicing process,and high-pressure extrusion frame steel casing connected nodes,instead of the traditional welding process,in ensuring the strength of the frame,while the frame production efficiency of about 67%.(4)Performance Evaluation of tetrahedral framework cold steel sleeve s queeze connection.To assess the mechanical properties of cold extrusion steel c asing to connect the molding frame and find an optimized connection,a study on mechanical properties of cold extrusion steel casing connection node are car ried out.Steel casing using different materials,different extrusion dies,different length of indentation,different pressures,different extrusion steel with smooth surface model made of the mechanical properties,obtained the relationship betw een the strength of the connection and the test parameters,proposed optimal co nnection design. |
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