METHOD FOR ACOUSTICALLY MEASURING A FLUID FLOW RATE

摘要

A method for measuring the flow rate of a fluid between two points in a fluid flow, wherein a measurement of the respective propagation times of two acoustic signals transmitted in opposite directions is combined with a measurement of the acoustic phase-shifts respectively induced in each signal, each received signal is sampled and digitised and the corresponding acoustic phase-shift is determined by synchronous detection. The method comprises a series of iterations each of which involves determining a programmable phase-shift dependent on the value of the acoustic phase-shift produced by synchronous detection in the previous iteration, whereby the result of the synchronous detection step in the current iteration is as close to zero as possible, and the acoustic phase-shift is therefore substantially the same as the last programmable phase-shift.