Research Of Flow Measurement Of Two-dimensional Flow Field Adaptive To Non-uniform Velocity Profiles

A lot of large bore pipeline flow measurement problems appeared in energy and resource industry.Due to the limitation of installation space,the duct flow is usually not fully developed so that velocity profiles in conduits are non-uniform.In order to accurately measure the flowrates of non-uniform velocity profiles in large bore pipelines,the insertion electromagnetic flowmeter was applied and the flowrate was calculated with the local velocities at measuring points in this paper.Theoretical studies of velocity profiles of two-dimensional flow field in circular conduits,the mathematical models of the characteristic points,the principle of the insertion flowmeters and the structure of the measuring probes were conducted,and a multi-sensor insertion electromagnetic flow measurement equipment and an experiment scheme were designed.In addition,fitting curve method—a new calculation method of flowrate with multi-point velocities adaptive to non-uniform velocity profiles was presented.Finally,the simulation experiments were conducted by FLUENT software: 1.build several non-fully developed flow fields to conduct the flow field analysis and select the optimal mathematical model of the characteristic points—Log-Chebyshev method;2.simulate the flow fields around the insertion flowmeters,analyze the influence of the insertion flowmeters on the flow fields,and compare the advantages and disadvantages of two types of measuring probes;3.simulate the flow fields around the multi-sensor insertion electromagnetic flowmeter and collect the simulation data of the local velocities at measuring points.The simulation data of the local velocities were integrated respectively based on fitting curve method and arithmetic average method using MATLAB software,and the two calculation methods were compared and analyzed.The result of the comparative analysis suggested that fitting curve method could considerably improve the measuring accuracy of fluid flowrate by means of insertion flowmeters and especially be adaptive to non-uniform velocity profiles for non-fully developed pipe flow.