| The SmartPlug is a new isolation tool used in the repair and maintenance of pipeline.It can isolate high-pressure fluid inside pipe controlled by wireless communication under the nonstop condition.In the process of plugging,the parameters of flow field change significantly,so it is necessary to analyze the evolution law of flow field to insure the safety of plugging work.The result can guide the control optimization of plugging movement.In this paper,the SmartPlug model is designed can be used in the 50 mm pipe,the stationary of plugging movement is analyzed by mechanical dynamics.According to the similarity principle,the experimental rig is designed and set up.The experiments simulate the dynamic plugging process under different velocity.The experimental data is analyzed in time-domain and frequency-domain,and the obtained flow equation of inlet is applied to modify the boundary condition of numerical simulation.On this basis,the 3D numerical simulation of static model under six kinds of plugging ratio and dynamic model used UDF are conducted under the same condition.The comparison of data reveal the good consistency above them.The results show that,in the plugging process,the recirculation zone in the downstream continuously extend and the crossly distributed eddies appear that result in the pressure fluctuation which basic frequency is 50 Hz in pipe.Meanwhile,the differential pressure between upstream and downstream show an increasing trend and the difference of growth rate is obvious.Based on analysis of the experiment and simulation results,the control strategy has been proposed that divide the plugging process into two stages: fast plugging and slow plugging.Moreover,the security reference value of change rate with time of differential pressure is defined.The critical plugging speed function is obtained by using the least square method,and it is verified that the optimized plugging velocity function is better than the constant velocity through numerical simulation. |
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