Factors which influence the variability of turbine flowmeter signal characteristics

Abstract There have been suggestions that the detailed characteristics of the signals from turbine flowmeters can be used to derive information about both the `health' of the meter and features of the flow through it. To assess the feasibility of such suggestions, information is needed on the variability of signal characteristics obtained from meters in nominally identical flows. This paper reports data obtained during tests performed at the National Engineering Laboratory (East Kilbride, Glasgow). The majority of the tests involved a 100 mm diameter turbine meter installed in the oil flow calibration facility but data were also collected for different diameter meters and different fluids. A significant component of the signal characteristic is shown to depend on physical features of the turbine blades and to be representable as an array of `blade spacing unevenness'. The variability associated with estimates of this parameter is established and the possibility that changes in the parameter can be correlated with changes in meter calibration is examined. The variability of other parts of the signal characteristic with changes in flow conditions both upstream and downstream of the meter is examined.