Prediction Of Critical Non-silted Flow Velocity For Pipeline Transportation Based On FLUENT

In order to ensure safe,reliable and effective slurry transportation and efficient slurry transportation,it is necessary to conduct in-depth research on the flow state of slurry in the pipeline and accurately predict the critical non-silt flow rate.At present,the research on the non-silting flow rate of filling slurry at home and abroad is mainly aimed at a single 90°elbow pipe,which cannot reflect the change of the critical non-silting flow rate caused by different elbow angles in the actual slurry transportation process.In this paper,theoretical analysis and numerical simulation are combined to study the flow characteristics of coal gangue filling slurry in a coal mine at different angles.Numerical simulation research was carried out to study the conveying characteristics of bent pipes.The main work and research results are as follows:(1)The measuring method and influencing factors of critical non-silting flow rate,the characteristics of solid materials,and the concept and model of slurry rheology are introduced.This paper introduces the judgment method of the predecessors on the critical non-silting flow rate,and determines the judgment method of the critical non-silting flow rate used in this paper,that is,during the filling process of slurry transportation,the critical non-silting flow rate is judged according to the distribution of coal gangue particles;According to the properties and characteristics of the solid materials used,it is determined that the mass fraction of coal gangue in the slurry is 78%,the density of coal gangue is 2.3×10~3kg/m~3,and the density of the slurry is 1.9×10~3kg/m~3;according to the filling material The pulp properties were determined using the Euler model as the mathematical model for numerical simulations in this paper.(2)Fluent software is introduced and three-dimensional physical models of a coal mine pipeline and three different elbows are established.In this paper,Design Modeler is used to establish a pipeline physical model,a coal mine is scaled down to 1:100 to establish a model,and a physical model of 75°,90°and 105°elbows is established;The model parameters and boundary conditions are established for different working conditions,and certain assumptions are made for the numerical simulation process.(3)The influence of the change of elbow angle and pipe diameter on the critical non-silted flow velocity was analyzed.In this paper,the angle of the elbow and the diameter of the pipe are used as variables,and the Fluent software is used to simulate the transportation process of three kinds of elbows when transporting the filling slurry,and the pressure of the pipeline and the flow rate of the filling slurry are analyzed.And the change of the critical non-silted flow rate when the pipe diameter changes.The research shows that the non-silted flow rates of gangue slurry in 75°,90°and 105°elbows are 1.8m/s,1.7m/s and 1.5m/s,respectively.The larger the elbow angle,the slower the filling slurry flow rate.,the smaller the value of the critical non-silting flow rate,on the contrary,the smaller the angle of the elbow,the larger the value of the critical non-silting flow rate;under the condition that other conditions remain unchanged,the larger the pipe diameter,the lower the pipe pressure,the smaller the filling slurry flow rate,and the critical The non-silt flow rate decreases accordingly.(4)In this paper,a study on the critical non-silt flow rate of a coal mine filling pipeline was carried out.The study showed that the mass fraction of coal gangue in the slurry was78%,the density of coal gangue was 2.3×10~3kg/m~3,and the density of the slurry was1.9×10~3kg/m~3,the yield stress is 368.3Pa,the viscosity is 0.5Pa·s,and the pipe diameter is0.12m.Under the above conditions,the critical non-silting flow rate of the coal mine pipeline filling slurry is 2.6m/s is the most suitable.