On the use of a confuser to improve the accuracy of an ultrasonic flow meter

Unlike conventional gas meters, ultrasonic flow meters have advantages such as non-contact operation, minimal pressure loss and high accuracy. The use of integration methods in the theory of ultrasonic flow meters also imposes its own requirements on the profiles of the gas flow velocity passing through the flow meter. To level the flow profiles, devices such as flow straighteners in the form of perforated disks or disks with guide blades, as well as changes in the geometric shape of the flow part of the flowmeter, can be used. The work analyzes the influence of the narrowing of the flow part of a two-beam ultrasonic flow meter on the accuracy of measurements. The influence of the tapering part of the flow meter on the accuracy of its readings is shown. The article compares integration errors in a flow meter for different diameters of the flow path, as well as for different numbers of flow meter beams at different Reynolds numbers. It has been demonstrated that three-beam and four-beam integration schemes are more accurate than the two-beam scheme. The flow velocity profiles in the flow meter were compared. It has been shown that narrowing the flow part of the flow meter improves the measurement accuracy by reducing the integration error. The effect of changing the shape of the flow profile as a result of narrowing the flow part of the ultrasonic filter is estimated at 0,1–0,3 % over the entire operating range of the flow meter. At the same time, a zone was identified in the region of the laminar-turbulent transition, in which the narrowing of the flow part of the flow meter has a negative impact on the measurement accuracy. The critical speeds corresponding to this area are indicated. It is shown that the number of rays does not affect the existence of the identified region.