Design and testing of an experimental platform for fluid flow and pipe deformation measurement in pipe-in-pipe structures
[Objective]With a distinctive structural configuration,the"pipe-in-pipe"structure can protect the inner pipe transmission,isolate seawater,and effectively prevent heat dissipation during the production process,thus providing vital support for offshore oil and gas extraction.However,the pipe-in-pipe structure faces intricate loads stemming from environmental factors such as external wind,waves,currents,internal oil and gas pressure,and platform drift.Hence,it is imperative to develop an experimental platform for examining the mechanical and fluid flow characteristics of the pipe-in-pipe structure.Such an initiative lays the groundwork for further theoretical and simulation research on the mechanical and fluid mechanics of the pipe-in-pipe structure while broadening the scope of education regarding the structure's load-bearing capacity.[Methods]Drawing from the load-bearing attributes of the offshore pipe-in-pipe configuration,this article proposes an experimental platform to gauge fluid flow and pipe deformation within the structure.It investigates the deformation and seawater flow reactions of various pipe combinations,simulating the fluid flow and deformation dynamics of the offshore pipe-in-pipe structure under diverse influences.To accentuate the dynamic response traits of the inner and outer pipes and bolster the effectiveness of teaching and research,PVC piping is chosen as the primary material for the pipe-in-pipe structure.To account for the deformation traits of both inner and outer pipes and ensure data acquisition from upper and lower"1/3"points,eight strain gauges are evenly positioned on the water-facing surfaces of both pipes for deformation measurements.The constructed data acquisition system can provide a real-time display of test curves and parameters while also storing and recording test results.According to operational scenarios of deepwater pipe-in-pipe structures,an experimental procedure and its steps are designed to replicate the structure's deformation under varied influences,such as diverse top tensions,ocean currents,internal flows,and water depths.[Results]The experimental findings can be summarized as follows:1)Under identical parameters,the deformation at the 15 cm section of the inner pipe escalates with the outflow velocity.2)As the coefficient of top tension increases,the deformation at various measurement points on the inner pipe decreases.The increase in top tension effectively mitigates inner pipe deformation.3)The increase in internal flow velocity correlates with both maximum and overall inner pipe deformation.4)With increasing water depth,inner pipe deformation decreases.Remarkably,once the water depth surpasses 80 cm,inner pipe deformation notably decreases.This reduction is attributed to escalating internal and external static pressure,which suppresses deformation.[Conclusions]Through the design and experimentation conducted on this platform,it becomes feasible to simulate and analyze the fluid flow and pipe deformation characteristics of both inner and outer pipes under varied parameters such as top tension,water depth,outer pipe flow velocity,and inner pipe flow velocity.This study establishes a robust groundwork for verifying and refining theoretical investigations concerning pipe-in-pipe structures.Moreover,the development and utilization of this experimental setup can enrich students'comprehension of offshore pipe-in-pipe systems'structure and operation.It furnishes students with a more tangible grasp of the loading,deformation,and failure mechanisms inherent in such structures.Additionally,it aids students in conducting innovative experimental research on the dynamic response of pipe-in-pipe structures,thereby fostering their innovative thinking.
pipe in pipefluid flowdeformationexperimental platformtest
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