Multiple reflective signal reception in gas flow measurement using air-coupled leaky Lamb waves

Abstract

This work investigated the signal reception from multipath including direct transmission and reflection paths in a non-contact gas flow measurement system based on air-coupled leaky Lamb waves. Analytical model was established to provide the multiple reflective signal propagation time differences between upstream and downstream paths at different flow velocities. A multiphysics model based on finite element methods was established to facilitated the visualisation of the leaky Lamb waves reflected between the plates and the Lamb waves excited by multiple reflective paths waves. The propagation time differences were evaluated by performing simulations and experiments, which are in good agreement with the analytical values (RMSE are 0.0708 and 0.0767 respectively). The receiver can collect multipath signals at a large distance separated from the transmitter. Time resolution is enhanced by using received signals from reflection paths, as the transit time increased with the ultrasound path between the transducers.