Modification features of the measurement equation for vortex sonic flowmeters

Vortex sonic flowmeters are widely used in the area of housing and public utilities due to their insensitivity to the quality of the measured fluid. Nevertheless, vortex shedding is unstable at low flow rates, which results in an increase of flow measurement errors within this range. This article describes the model of measurement equation for vortex sonic flowmeters based on experimental research of two types of flowmeters with 32 and 50 mm flow tube diameters. The adequacy of the obtained measurement equation model is confirmed based on three types of flowmeters (including the flow tube diameter of 25 mm) and other test modes. The resulting refined model of the measurement equation enables reducing the measurement error from 3 % (rated value) to 0.5 % at low flow rates.