The Investigation On The Characteristics Of Turbine Flowmeter Based On Reynolds Number

Due to the advantages of fast response,high precision,wide measurement range,and so on,the turbine flowmeter is commonly used as master meter in woking gas flow standard facility to calibrate other types of gas flowmeters.There are basically two conditions including fixed point and non-fixed point.So far,domestic researches are mostly focus on the atmospheric pressure,however,the pressure can influence the accuracy and reliability of the turbine flowmeter.Therefore,this thesis intends to further the investigation on the characteristics of turbine flowmeter on the basis of Reynolds number.In 2014,a set of high pressure gas flow standard facility have been 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.The high pressure close loop gas flow standard facility was used as the experimental platform and measures the performances of the facility by a Dn100 flowmeter in this paper.The results are as follows: with 4 sets of turbine meters as its master meters,the high pressure close loop gas flow standard facility can operate at the maximum flowrate of 1600 m~3/h under 2.5 MPa pressure.The expanded uncertainty was 0.21%(k=2).Based on the capability of the high pressure close loop gas flow standard facility,the curve of meter error based on Reynolds number was investigated.The experimental results showed that and results showed that:1)With the NIM-2014 model,the curve of meter error might be obviously spreaded under the critical Reynolds number.The lower the flow and pressure the high deviations from this behaviour.2)Based on the new bearing friction torque model,the NIM-2015 model was presented.3)Compared to the uncertainty based on the NIM-2014 model,the uncertainty based on the NIM-2015 model of the 4 turbine flowmeter for the non fixed point uasge was decreaed from(0.35% ~0.42%)(k=2)to(0.22% ~ 0.25%)(k=2),.On the other hand,the consistency of the master turbine flowmeter was analyzed with 3 meter under test,the results showed that: the characteristics of the turbine meter in the non fixed point usage could be good evaluated by the NIM-2015 model.