Patent ID: 8225678
Filing Date: 2012-07-24
Classification: G01F

Abstract:
1. A fluid flow meter, comprising: a conduit; a heater configured to heat fluid at a heating location in the conduit; sound speed sensors configured to measure a speed of sound in fluid flowing in the conduit at a plurality of sensing locations downstream from said heating location; a data processing circuit configured to determine flow speed of the fluid flowing in the conduit from a delay with which a time dependence of heating strength by the heater is detected in sound speeds in fluid flowing in the conduit measured by the sensors; and wherein the data processing circuit is configured to dynamically select a frequency or frequency range of the measured time dependence of heating that is used for determining the flow speed of the fluid flowing in the conduit, the selection of the frequency or frequency range being dependent on the determined flow speed and/or fluid properties measured in fluid flowing in the conduit at a time the sensors measure the speed of sound in fluid flowing in the conduit.