Dispersion and aggregation of turbine meter calibration curves under multi-working conditions

Due to the lack of sufficient data comparison, the discrepancy of turbine meter calibration curves under multi-working conditions is always a topic of concern. The applicability of verification conclusion and calibration data at atmospheric pressure to high-pressure turbine meter is still a controversial issue in natural gas custody transfer. Turbine meters are calibrated at three operating pressures from 1.6 to 5.0 MPa in a high-pressure closed loop test rig to compare calibration curves under multi-working conditions. The significant dispersion of three calibration curves is observed in the low Reynolds number region. The maximum difference between calibration data is 0.65%. The curves gradually approach each other with increasing Reynolds number before the eventual difference is less than 0.2%. The behavior of calibration curves is analyzed and explained by the functional form of a physical model. Results show that bearing drag is responsible for the dispersion of calibration curves, while curves tend to be aggregate since the fluid viscous drag torque dependent on Reynolds number dominates the retarding torques as the Reynolds number increases. Similar behavior is also observed in multi-viscosity liquid calibration experiment, which suggests its relation to kinematic viscosity. Aggregate curves mitigate the effect of condition-induced variations in fluid properties on the accuracy of turbine meter. If good linearity is maintained at higher Reynolds number flows, the turbine meter can be applied to multi-working conditions with satisfactory degree of confidence. © 2020, Science Press. All right reserved.