Generalized Model Of Tube-contained Material Hydraulic Transportation In Pipe

The tube-contained material hydraulic transportation in pipe is a new typeof material conveyance in the development process of the logistics industry. Ithas advantages of energy saving, environmental protection and so on. Theproposed transport form alleviates high energy consumption, pollution and otherproblems in the traditional logistics industry to some extent.In the conducted study of the new type of transportation, someachievements in carriage operation conditions and motion characteristics havebeen made. In the study process, the whole running process of the carrier isdivided into several states, such as static (before starting or failing to stop at acertain position), starting, changing speed (including acceleration anddeceleration) operation and stable operation, for separate discussions. Atdifferent statuses, the dual roles of carrier’s various motion characteristics andpipe wall’s constraint produce different impacts on the flow. Characteristics ofthe flow field are the main aspects deciding the transport efficiency of thistransportation method. Therefore, a systematic study for hydrauliccharacteristics of the pipe flow field is required. As the first step in thesystematic study, an exhaustive research will be conducted concerningcharacteristics of the flow field around the carrier when it is not moving. At thisstate, the annulus flow, formed by water passing the pipe carriage, mainlypresents as the detour flow along the cylindrical barrel busbar. In order to facilitate the research and improve the accuracy, a cylindrical body of the sametype (including structure and size of each part, the carriage barrel is generalizedto be the main cylinder and the supporting structure is generalized to be theattaching cylinder) with the material carrier is established to generalize the studyto be a study of field characteristics of the flow around the cylindrical body inthe finite pipe domain (mainly means its inner diameter is finite).The paper analyzes and studies hydraulic characteristics of the flow filedaround the cylindrical body in the finite pipe domain using methods ofcombination of theoretical analysis, numerical simulation and experimentalverification，integrating projects funded by National Natural Science Foundationof China. These projects are “Energy consumption research of pipe carriagestrain in pipe hydraulic transportation”(51179116) and “Hydraulic characteristicsresearch of annulus flow with moving boundary”(51109155). The maininvestigated contents are shown in detail as following:(1) For characteristics of the cylindrical body structure, the flow pattern andthe velocity distribution change formed by the disturbance impact from the bodyon the flow in the straight pipe is analyzed theoretically. The pressure changeand the produce of the water energy consumption along the pipe flow aretheoretically studied.(2) The simulation software FLUENT is used to simulate the flow around asingle cylindrical body, in the straight pipe under different Reynolds numbers.Numerical simulation results are used to analyze the detour flow structure in thecalculation field. Several main sections are divided such as flow far away fromthe cylindrical body following the logarithm velocity distribution of turbulenceflow pattern in circular pipe, the upstream water-resisting region with lowvelocity and high pressure, the annulus space around the main cylinder withhigh velocity and low pressure, and the wake region behind the cylindrical body.In the wake region, the section near the cylindrical body is low-velocity corearea with violent turbulence flow. Afterwards, the turbulence weakens gradually with the flow flowing. Besides, velocities in three directions, pressuredistribution in each feature space and vorticity in the flow field, forcecharacteristics on the cylindrical body and so on are analyzed and described indetail, in which the flowing mechanism of the flow around the cylindrical bodyis combinational discussed.(3) Based on numerical simulation results, impact effects on flow fieldcharacteristics in the pipe domain from different factors (cylinder type and pipediameter) are concluded from the comparison analysis among different affectingfactors. The performances are that, the change of the main cylinder lengthdoesn’t change the axial velocity field structure and the increase of the attachingcylinder diameter reduces the low-velocity core range behind the cylindricalbody. Both of the two factors affect the pressure distribution on the cylindricalbody surface and the system resistance coefficient index slightly. Increasing themain cylinder diameter induces obvious increases of both the range of thelow-velocity core region behind the cylindrical body and the system resistancecoefficient index. The increase of the pipe diameter significantly reduces thedevelopment length of the annulus high velocity region along the flow directionand the system resistance coefficient index value. The main cylinder diameterand the pipe inner diameter are main factors affecting the pressure distribution inthe pipe domain and distributions of X-velocity and Y-velocity at the location ofthe annulus inlet.(4) The estimate method of the violent disturbance scopes before and afterthe single carriage is given through the non-dimension analysis and thenumerical data process. Meanwhile, the relationship between the violent scopecoefficient and the flow rate is established by fitting. Besides, the relationshipbetween the flow disturbance energy and the flow rate in the strong disturbancerange is fitted to be exponentiation.(5) For the structure of the annulus flow field around the single cylindricalbody, velocity distributions in annulus around the main cylinder and the full pipe space in certain scopes in the upstream and downstream of the cylindrical body,and pressure drop characteristics of the feature pipe segment along thecylindrical body are experimentally studied. Experimental results show that inthe upstream test sections of the cylindrical body, the water-resisting actioneffect leads to the slightly lower velocity at the center location than thesurrounding. And the wall viscous effect results that velocity near the pipe wallshows lower. In the downstream full pipe space, the velocity distribution turns tobe the ordinary distribution of inner higher and outer lower, and the velocitygradient reduces gradually as water flows forward.(6) The effectiveness and rationality of the numerical simulation areverified through the comparison between the experimental velocity data and thenumerical simulation results in feature sections, and pressure drops of thefeature pipe segment.