Study Of Velocity And Volumetric Coupling And Critical Velocities In Slurry Pipeline

The principles and mechanisms , for water carrying solid particles while slurry flows in a horizontal pipeline ,and the computing methods of various velocity distribution and hydraulic gradient in the pipeline are always hard problems ,which is paid attention and solved by experts and scholars engaged in the slurry transportation technology. Since last century, people have done plentiful experiences and theoretical researches .achieved a lot of research results. People have already put forward some hydraulic gradient formulas, critical velocity formulas, expecting velocities distribution formulas and volumetric percent distribution formulas etc. In these achievements, some were obtained from experimental researches, some were obtained from theoretical research, some were obtained from both . However, for the complexity and variety of the slurry flow, till now, none of the achievements could explain clearly the critical problem that water carries solid particles when slurry is flowing. Meantime, there are great deviations between the test result and the estimated result. Therefore, the study would help to develop long distance slurry pipeline transportation and accelerate the researches and developments of the solid-liquid two phases flows theory.This paper goes on according to the successful application of Prantle's half experiential theory formula of turbulent velocity distribution in the pipeline and ditch, using this method to study the turbulent velocity distribution of the bow-shaped section in the pipeline, thereby the turbulent velocity distribution with fixed bed in the pipeline has been obtained. The author designed an experiment to prove the turbulent velocity distribution of bow-shaped section. On the basis of the slurry velocity distribution model, the author considered the interfering force that would influence solid particle velocity; at the same time, saw the motion state of the solid particle as a standard to choose which formula to be used, in this case, the original three models to would be in one calculating model. Not only improves the calculated accurate degree but also make the model simplified, easy to be calculated and applied; Volumetric percent distribution formula from diffusing theory combines velocity distribution formula to set up a coupling model of volumetric percent distribution and velocity distribution. The mode! can be used to calculate velocity distributions and volumetric percent distribution under some conditions in the pipeline and some examples are used to prove the coupling model is correct. According to turbulent velocity distribution in the pipeline with fixed bed, combining solid particle storting terms, the storting velocity model is obtained and some examples are used to analyze the influence trend of effect factors. According to slurry velocity distribution model and starting terms of solid particle at the bottom of the pipeline, deposit velocity model is set up and some examples are used to prove the model is correct and analyze the influence trend of effect factors. According to slurry velocity distribution model and thickness formula of process layer, suspending critical velocity model is obtained when process layer thickness is zero and some examples are used to provethe model is correct and analyze the influence trend of factors to suspending critical velocity. According to slurry coupling model of velocity distribution and volumetric percent distribution, combining Wasp's criterion of judging homogeneous slurry, homogeneous critical velocity model is obtained. Some examples are used to prove homogeneous critical velocity model is correct and analyze the influence trend of factors to homogeneous critical velocity. According to slurry velocity distribution model, water velocity before momentum transfer can be obtained and water-power gradient can be gotten, this is equal to slurry water-power gradient. According the water power gradient formula, it can get the minimum water power gradient in all area, the corresponding velocity is critical velocity, the critical vel...