Fluid flow meter

摘要

A fluid flow meter comprises a pair of transducers (8,9) spaced apart in the direction of fluid flow. Acoustic signals are transmitted in both directions through the fluid by the transducers. A processor (22) determines information relating to the fluid flow by monitoring the time of flight of acoustic signals received by the transducers. Part of the space between the transducers defines a flow path consisting of a substantially annular flow passage (82), wherein the radial dimension (d) of the annular flow passage is such as to permit propagation of substantially only plane wave acoustic signals. <IMAGE>