Influence of elbow pipe on gas measurement accuracy of ultrasonic flowmeter and improvement

Abstract

When the fluid passes through the elbow, it is easy to produce secondary flow, eddy flow, etc. The velocity distribution in the sonic flow channel is not symmetrical, which has an impact on the measurement accuracy of the flowmeter. In order to study the influence of turbulence on flowmeter by means of modelling and simulation, the measurement effect of G16 single-channel flowmeter is firstly studied under this condition. The condition is that the inlet pipe is double-bend pipe and half-moon double-bend pipe, and calculate the flow error in the two cases relative to the straight pipe. The single-channel flowmeter is installed with the elbow, the influence of the turbulence has brought a large error to its measurement results. In order to reduce this error, the model of G16 double-channel flowmeter was established, and the simulation experiment was carried out under the same conditions. Finally, the data obtained is compared with the corresponding data of the single-channel flowmeter. By developing real prototype units, we calibrate several the single channel and double channels ultrasonic gas meters on the sonic nozzle calibration system. Comparison of error accuracy curve and repeatability, the double channels are much better than one channel units. The conclusion: Compared with the single channel design, the double channels one greatly improves the influence of turbulence caused by the elbow and the measurement accuracy is improved.