The Investigation On The Characteristics Of Turbine Flowmeter Based On High Pressure Sonic Nozzle Gas Flow Standard Facility

Due to the many advantages,such as high precision,wide measurement range,and so on,the turbine flowmeter is commonly used as master meter in working gas flow standard facility to calibrate other types of gas flowmeters.In the end of 2014,a set of high pressure gas flow standard facility was constructed in National Institute of Metrology of China,including a high pressure pVTt primary gas flow standard facility,high pressure sonic nozzle secondary gas flow standard facility and high pressure close loop working gas flow standard facility with turbine meters as master meter.The master meter in the close loop facility was traced to sonic nozzle facility.Furthermore,the error characteristics evaluation on the non-fixed point usage for the turbine meter was a big problem,within the pressure range of(100~2500)k Pa.In this thesis,the uncertainty analysis for the sonic nozzle facility and the influence from the linepack effect was conducted.The capability of the sonic nozzle facility was verified with the comparison.On the other hand,the influence of Reynolds number on the error characteristics of turbine meter was investigate.The following conclusions were gotten.1)The high pressure sonic nozzle secondary gas flow standard facility could operate at the maximum flowrate of 7200 Nm3/h at 2.5 MPa pressure.The expanded uncertainty was 0.15%(k=2).The influence of linepack effect resulted from the temperature,pressure change during the measurement was smaller than 0.03%.2)With 5 turbine meters as transfer meter,the comparison between NIM and PTB was conducted.The capability of the sonic nozzle facility,the expanded uncertainty 0.15%(k=2)was verified with all the value of En smaller 1,or En ?1.3)The performance of the turbine flowmeter was strongly influenced by the pressure.At low Reynolds number,the indication error of turbine flowmeter was shown as scattered tendency at different pressures;At high Reynolds number,the indication error of turbine flowmeter was shown as concentrated tendency at different pressures.4)Based on the NIM-2014 model,the uncertainty of piecewise fitting could be smaller than 0.05%.So,the piecewise fitting method might be the best choice to evaluate the error characteristics of turbine meter for non-fixed point usage.