Optimization Design And Research Of Wet Concrete Spraying Machine Nozzle

Wet spraying machine is an important tool to spray concrete supports.It is widely used in mines,road tunnels,culverts,mine tunnels and water resources and hydro-power engineering.Spraying nozzle is the core part of this machine.Reasonable structural design and good matching relations of structural indexes have direct influence to mixing uniformity degree produced by spraying nozzle outlets.Hence resilience values of working spraying nozzles are affected.However in practice,structural design is not reasonable,resulting in problems like uneven mixture of materials,bonding of materials in pipe walls,great resilience values and severe pulses,etc.In order to solve those problems,this paper makes following researches:1.Construct a mathematical model of mixing fluids in spraying nozzle by using basic theories of multi-phase flow.Through theoretical calculation,the speed and pressure of mixing fluids in spraying nozzle outlet are got.This paper analyzes mixing mechanism of fluid phases in spraying nozzles like sand,accelerator,compressed air and cement paste.According to their flow characteristics,this paper selects suitable numerical simulation methods and turbulence models.2.Simplify structural models of spraying nozzles,design flow field analysis model in pre-processing software Gambit,make mapped meshing of different regions in spraying nozzles,and finally define various boundary types.3.Guide divided grids into software Fluent,and make numerical modelings on mixing fluids in spraying nozzles.We can know distribution of velocity field,pressure field and volume fraction of fluids' different phases in spraying nozzles.This paper makes an analysis on relationship between fluids distribution and spraying nozzle structure,finishes an quantitative analysis on degrees of mixing uniformity by using mean value and standard deviation in mathematical statistics.Hence uniformity of compositions and speeds in different sections within spraying nozzles can be received.4.In order to boost mixing effects of mixing fluids in spraying nozzle outlet,this paper makes preliminary improvement in spraying nozzle structure.By introducing orthogonal experiment methods,this paper refines structural index of improved spraying nozzle.It designs 16 sets of testing programs,by taking outlet composition uniformity and speed uniformity as performance check indicators,and incident angle ofmud pipe,length of premixing tubes,length of reducer pipes,and length of material gathering pipes as optimal parameters.The paper makes numerical simulation on 16 sets of structural models by using Fluent software,and analyzes researching findings by means of range analysis methods.Therefore influencing orders of mixing degree parameters in spraying nozzles,as well as the best structural parameter combination of spraying nozzles,is achieved.The researching conclusions are instructional to structure design of spraying nozzles.