Flow Field Analysis And Velocity Prediction Of Velocity Control Module Of Fluid Driven PIG

With the development of pipeline transportation,the safety of long-distance oil and gas pipelines has become a key factor affecting the national economy and improving social and people’s livelihood.It adjusts the pressure changes generated by the fluid at the front and rear ends,and was suitable for the inspection of oil and gas pipelines.However,in long-distance oil and gas pipelines,the Pipeline Inspection Gauge(PIG)cannot work continuously and stably,and its own working rate must be adjusted to improve its monitoring effect.At present,there were two main types of PIGS: fixed orifice PIGS and variable orifice PIG.Combining theoretical research,this thesis has been carried out extensive and in-depth research on the motion laws of the two PIGS under their respective working conditions.The main work and research contents were as follows.1.The research on the speed regulation characteristics of the fixed throttling PIG was carried out.By analyzing the driving and speed regulation principle of the PIG,a mechanical model was established.The operation of the fixed throttling PIG in the pipeline was analyzed,and the influence of the density and dynamic viscosity of the fluid medium on the movement of the PIG was obtained.Through the combination of CFD simulation analysis and friction mathematical model,the driving force and friction force of the PIG under different through-hole diameters and different operating speeds were obtained respectively,and the moving speed and bypass of the PIG were determined.The relationship between the valve through hole diameter.2.The speed regulation characteristic of variable throttle PIG was researched.Through the modeling and CFD simulation analysis of the variable-throttle PIG,the influence of the variable-throttle PIG’S operation in the pipeline was studied.The variation law of the fluid driving force and frictional resistance and the speed of the PIG at different valve openings of the PIG was obtained.By fitting the curve,the prediction curve of the movement speed of the variable-throttle PIG with the valve opening was obtained,which provides a theoretical basis for the structural design of the variable-throttle PIG.3.Carried out the overall design of the prototype of the variable throttling PIG.Through the analysis of the factors affecting the structure of the variable throttling PIG,the size and structure of the stator and rotor of the valve were analyzed,and the hydraulic torque of the valve was calculated.The driving structure was determined according to the hydraulic torque,the driving structure and the sealing structure were designed,and the strength of the structure design was verified.