Study On Influence Of Installation Condition Difference On Measurement Performance Of Ultrasonic Flowmeter

At present,the widely used time-difference ultrasonic flowmeter is the velocity flowmeter,and the fluid velocity distribution in the pipeline is the main factor affecting the measurement accuracy.For complex natural gas metering sites,different installation conditions will cause a certain difference in the flow field in the pipeline,thus affecting the measurement accuracy of the ultrasonic flowmeter.In this paper,the numerical simulation method is used to simulate the ultrasonic flowmeter under different installation conditions,and the influence of the installation condition difference on the measurement performance of ultrasonic flowmeter is studied.Firstly,the simulation models of ultrasonic flowmeter under different installation conditions are established,and the reliability of the numerical simulation method is verified by field real test.The results show that the simulation results of the influence of two different rectifiers on the measurement performance of Elster ultrasonic flowmeter are consistent with the trend of field test results.And considering a variety of influence factors,it is considered that the numerical simulation method can qualitatively and semi-quantitatively study the influence of different installation conditions on the measurement performance of ultrasonic flowmeter,which verifies the reliability of the numerical simulation method.Then,aiming at the common installation conditions of the ultrasonic flowmeter in the natural gas metering field,the influence of the installation condition difference on the measurement performance of ultrasonic flowmeter is studied.The results show that the different structural rectifiers have the greatest influence on the measurement performance of Elster ultrasonic flowmeter,and the maximum difference of indication error is about 0.48%.The different straight pipe lengths have the greatest influence on the measurement performance of RMG ultrasonic flowmeter,and the maximum difference of indication error is about 0.24%.The different pipe wall roughness has the greatest influence on the measurement performance of Elster ultrasonic flowmeter,and the maximum difference of indication error is about 0.39%.Therefore,in the actual natural gas measurement field,the influence of the installation condition difference on the measurement performance of ultrasonic flowmeter cannot be ignored.Finally,the internal flow field of ultrasonic flowmeter under different installation conditions is analyzed.And it is pointed out that the difference of the internal flow field caused by different installation conditions is the fundamental reason that affects the measurement performance difference of the ultrasonic flowmeter.The results show that for the installation conditions of different structural rectifiers,the velocity distribution formed by CPA50 E rectifier is closest to the fully developed velocity distribution.For the installation conditions of different straight pipe lengths,the velocity distribution formed by the 30 D straight pipe is closest to the fully developed velocity distribution.For the installation conditions of different pipe wall roughness,with the increase of roughness,the velocity distribution shape of the fluid in the pipe becomes more and more sharp.