Study On The Influence Of Wettability On Pipeline Flow Resistance

With the development of modern testing methods and analysis techniques,some studies have shown that the wettability of liquid and solid surface leads to the failure of the no-slip hypothesis in classical fluid mechanics theory in some special cases,and the existence of boundary slip changes the flow resistance of fluid.Therefore,it is of great significance to study the influence of wettability on resistance loss of pipeline transportation.In this paper,the flow resistance characteristics of water and ethylene glycol in PVC,stainless steel,plexiglass and PTFE pipes were studied by pipeline flow experiments,the relationship between wettability and friction coefficient of pipeline is analyzed qualitatively,the resistance loss in pipelines with smaller contact Angle is closer to the result calculated by classical theory,with the increment of contact angle,pipe friction resistance decreases.Through the study of the linear regression of experimental data at the same time,establishes the regression model,the turbulent flow quantitatively analysis the relationship between the wettability and frictional resistance coefficient,through experiment data testing model values than the classical theory of fluid mechanics is closer to actual value.On the basis of the influence of wettability on pipeline flow resistance characteristics,this paper continues to study the influence of liquid viscosity on wettability drag reduction,by changing the mass fraction of polyacrylamide(PAM)solution to get different viscosity of liquid and pipeline flow experiments in stainless steel pipe,plexiglass pipe,PTFE pipe.The experimental results show that viscosity will change the Reynolds number-friction coefficient curve.When Reynolds number is constant,friction coefficient is negatively correlated with viscosity.When the viscosity is small,the wettability has obvious influence on the pipeline flow resistance.The larger the contact Angle is,the smaller the pipeline resistance loss is.When the viscosity is large,because the viscosity is too large,the internal friction in the pipeline is too high,leading to the influence of wettability on friction coefficient is not obvious.Fluent software is used to simulate wettability by setting contact Angle in the twophase flow model to conduct numerical simulation research on the influence of wettability in pipeline fluid flow.The simulation results show that the pipeline flow resistance decreases with the increase of the contact angle.The reliability and accuracy of the simulation method were verified by comparing with experimental results.At the same time,through the analysis of the velocity cloud map in the middle section of the pipeline,it is speculated that the internal mechanism of wettability affecting the resistance loss of the pipeline is that the pipeline has boundary slip phenomenon with the increase of the contact Angle at the same inlet velocity.