Installation and Viscosity Effects in Turbine Meters

Turbine flow meters are commonly used in the oil industry. The rotor rotates freely and takes from the flowing fluid only the torque required to overcome its losses. The speed of rotation of the rotor is monitored with a pick-up which generates a pulse at the passing of each rotor blade. The calibration of the meter is presented as a curve of the meter's 'K-factor' (the number of pulses generated per unit volume of fluid passing through the meter) as a function of flow rate. For a given installation and fluid a meter's K-factor will typically be constant to within ±0.2% over 15% to 100% of the meter's design flow range. For the user, the difficulty in employing turbine meters is their sensitivity to installation effects and fluid properties; the upstream pipework and the viscosity of the fluid being metered can both affect the meter characteristics. The aim of this project was to use the FLUENT modelling package to try and identify aspects of meter design which affect the sensitivity to inlet flow and to fluid viscosity, and to check the predictions against meter calibrations carried out at NEL. In co-operation with Halliburton Manufacturing and Services Ltd, a modular, 102 mm diameter meter was designed and a range of components were manufactured. Several combinations were analysed using the CFD software, and calibrated with different upstream flow conditions and oils.