Study On Gas Flow Characteristics And Microchannel Simulation Of Sealing Surface In Gas Storage

In the operation,the reservoir is in high pressure,high temperature condition,and the direction of gas transmission is changed,thus the pipe has a strict requirement for air seal performance.With the acceleration of the construction of the gas reservoir in our country,the research on the stable operation of the storage gas reservoir and the performance of the column seal performance have more pressing realistic significance.There have been many researches on the mechanical study of pipe thread seal,but there is less research on the flow of gas under special conditions of the gas reservoir,the study of microscale gas cover leakage is still relatively empty.This thesis probed into the problem of the gas flow in the tubing string and the flow in microchannel of the sealing surface,using Fluent to simulate the gas flow within the channel.Starting from the gas flow state,combined with the compressible gas characteristics,real gas property,micro rough surface morphology and the theory of gas slip boundary,through the macroscopic and microscopic scales,analyze the flow characteristics of the gas and the change of the flow field,for further research on gas storage class under the working condition of high pressure cylinder seal leakage problem provides a train of thought.The main research content and results are as follows:(1)In the simulation of compressible gas flow in cylinder under the high pressure,using the UDRGS functions to invoke the NIST real gas data,get more accurately flow simulate of the gases,explored the flow pattern within the fluid domain,the law of eddy current change is summarized.On sealing surface gas flow simulation,by adding the variable flow boundary condition through the UDF program,the fluid velocity change and pressure response of different specifications of pipe and operating conditions were obtained under steady state and unsteady flow,it is founded that the fluid stress in the sealing surface of the leaky flow channel is small.(2)Using of fractal theory to construct the sealing contact surface micro rough topography model,combining the theory of rarefied gas effect to correct the boundary velocity slip,simulating the gas flow in microchannel.Results show that the rough surface morphology will significantly affect the gas velocity of channel,pressure,friction factor and near wall flow direction,rarefied gas effect makes gas near wall resistance decreases,and the coupling effect of the both is significant for microchannel gas movement.At the micro scale were considered in the simulation of compressible gas characteristics,the simulation results founded that the impact should not be ignored,compressible and incompressible gas channel center of maximum speed difference reached 15.7%.Compressible gas has a lower flow rate at the center of the channel,but its flow stability is stronger than the incompressible gas.(3)Micro channel leakage flow is difficult to detect by the conventional methods,cumulative may make full section sealing in systemic risk,the sealing surface should improve the machining accuracy and avoid wearing in assembly,to ensure safety.This thesis studied the conventional and microcosmic scale fluid flow of gas movement near the string sealing surface.There are some theoretical and practical implications for the interpretation and exploration of the sealing leakage of gas from Wells.