Simulation Analysis Of Dynamic Interaction Process Between Fluid And Moving Solid In Pipeline

Pipeline transportation is an efficient and convenient way of material transportation,which is widely used in industry and daily life.As two basic modes of pipeline transportation,there are various forms of interaction between fluid in the pipeline and moving solids during fluid transport and solids transport.It has an important impact on the efficiency,stability and reliability of pipeline transportation.However,traditional empirical or exper-imental based design methods are difficult to effectively evaluate this dynamic interaction,which limits the design effect.Combining with practical engineering cases,passive fixed-axis rotary motion,passive linear motion and active fixed-axis rotary motion are discussed in this paper.At the same time,it also studies the numerical simulation methods for the dynamic action of fluid and moving solids in the pipeline,and summarizes the process of physical laws in order to guide the design better and optimization of pipeline transportation system.The main contents of this paper includes:(1)Based on a DN600 butterfly check valve,the numerical simulation study of the passive fixed-axis rotary motion is carried out.The fluid-solid coupling dynamic simulation of the passive fixed-axis rotational motion of the valve plate is successfully realized,which uses the User-Defined Function(UDF)to obtain the force and moment of the fluid on the valve plate,predicts the real-time motion parameters of the valve plate based on the dynamics principle,and uses the dynamic mesh technology to control the position update of the valve plate.Furthermore,the simulation method is used to study the dynamic changes of flow field,pressure field,flow rate and hydrodynamic torque in the valve pipe under different inlet pressure conditions of the butterfly check valve.The valve opening and closing conditions are also summarized.(2)Based on the sample bottle in the vacuum suction container type pneumatic conveying device,the numerical simulation of the passive linear motion of the solid in the pipeline is carried out.In order to reduce the calculation of passive linear motion in the whole flow field,a fixed outlet in the flow field is intercepted,and the pressure drop along the path is estimated by the Darcy-Weisbach equation.The dynamic simulation of the passive linear motion of the sample bottle is successfully realized by using 6DOF dynamic mesh model to obtain the six-direction freedom of the sample bottle under the action of the fluid to predict the movement parameters in real time and using the dynamic mesh technology to control the position updating of the sample bottle.Furthermore,the simulation method is used to study the dynamic variation of the flow field,pressure field and air resistance of the sample bottle with the passive straight line of the sample bottle under different outlet boundary conditions,different vacuum degrees and masses.(3)Based on a millions of nuclear power reheat valves,the numerical simulation of solid active fixed-axis rotational motion in pipeline is carried out.According to use the regional slip grid technology to specify the movement law of the actuator in the valve plate area,and Mixed-out Averaging algorithm to transfer the flow field data at the static/dynamic interface,the dynamic simulation of fluid-solid coupling in the process of active fixed-axis rotation of reheat control valve is successfully realized.Furthermore,the simulation method is used to study the dynamic variation of pressure,velocity field and aerodynamic moment in reheat control valve with valve on-off at different inlet mass flow and start-stop speed.In this paper,the simulation method of dynamic interaction process between fluid and moving solid in pipe is studied,which solves the problems of grid definition,description of motion mode of moving solid,dynamic updating of grid and calculation stability brought by non-linearity in the process of dynamic coupling.The physical laws under typical working conditions are analyzed and summarized with examples,which provides effective support for guiding the design and optimization of complex pipeline transportation system.