Numerical Simulation Of Flow Characteristics And Experimental Study Of Flow Coefficient On Elbow Flowmeter

In this paper,four kinds of different diameter,three kinds of different bend diameter ratio of 90°circular pipe flowmeter are carried out pilot studies. According to forced vortex theory and experimental results,the laws of flow coefficient changing with the bending radius ratio and diameter and the relations of flow rate and pressure are studied.Test shows that in the certain bending radius ratio,flow coefficient varying with diameter is not constant.In this paper,the impacts of Reynolds number on flow coefficient are investigated.Researches show that the relations between flow coefficient and Reynolds number are more complex and affected by bending radius ratio,diameter and flow rate.When the diameter is large and Reynolds number is larger than 2×10~5,flow coefficient hardly varies with Reynolds number;when Reynolds number is smaller than 2×10~5,flow coefficient decreases with Reynolds number.When the diameter is small and Reynolds number is smaller than 2×10~5,the law of flow coefficient decreasing with Reynolds is not found. Therefore,when Reynolds number is small,the changes of flow coefficient still need further study.In this paper,using international current software FLUENT software as computing platforms and RNG k-εmodel as turbulence model,the pressure distribution along the Diameter,pressure distribution along the inside and outside wall and the impacts of bending radius ratio on pressure and the relations between flow rate and pressure of different diameter and bending radius ratio are studied.The results show that calculated and the measured values are very different for some sections and calculated results are consistent with the experimental results for the most sections,the relations between flow rate and flow coefficient are obtained.The results show that the flow coefficient is a constant which is accorded with the test results.According to the calculated results and test results,best flow measurement section is gained for different diameter,bending radius.Research shows that it existes a max velocity point along the diameter which is between the inboard and central axis.Three-dimensional numerical simulation shows that the max speed gradually migrates to lateral.Finally,in the sectionθ= 65°,the max speed contours separate which forms two independent max contours and develop to to the top and bottom with the angle increasing.Calculated results shows that in the sectionθ= 65°secondary flow appears. Subsequently,it becomes obviously which extends to the export.Because of existence of secondary flow,it forms a spiral flow along the elbow flowmeter.