PS-16 Adaptive Asymmetric Double-Path Ultrasonic Transit-Time Gas Flowmeter

In this study we demonstrate that a double-path ultrasonic transit-time gas flowmeter can be extended significantly in its rangeability by shifting the two receiving transducers by the same amount in flow direction, such that the length of one sound path is increased, the other decreased. Such an asymmetric configuration is optimized in terms of signal-to-noise ratio (SNR) for the range of higher flow velocities, because it compensates for the parasitic carry-along (sound drift) effect. Further, this approach enables the realization of an adaptive asymmetric UFM, where the two receiving transducers can be shifted during operation for optimum SNR depending on the gas flow velocity. Our results show that the asymmetric configuration increases UFM rangeability without drawbacks