In vortex flow meters, the frequency of vortex formation at a bluff body inserted into the flow is used to determine the flow velocity. The frequency is determined using a sensor that measures the time-dependent distortions of the down-stream flow field. But the (univariate) sensor signal contains more information than just the vortex frequency. We use this inherent extra information to verify if the pipe flow has the form expected for the correct mounting of the flow meter, and thus, if the flow measurement has the expected high accuracy. In designing the method, special care was taken to leave it robust with respect to uncertainties in the material properties of the fluid. In order to achieve this goal, the method makes use of the scaling properties of the Navier-Stokes equation. We present the theoretical background of the proposed diagnostic functionality and verify it on measurement data. In the experiments, irregularities that lead to more than 0.5% error in the output of the flow meter can clearly be detected.
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