Ultrasonic flow meter system and method for measuring flow rate

1. An ultrasonic flow meter system, comprising:

a conduit defining a channel;

at least one pair of first transducers mounted on the conduit and comprising a transmitting transducer and a receiving transducer for generating a first responsive signal, the first responsive signal having a first signal-to-noise ratio, the transmitting transducer and the receiving transducer arranged on a chordal path;

at least one second transducer mounted on the conduit for generating a second responsive signal, the second responsive signal having a second signal-to-noise ratio; and

a processor configured to receive the first responsive signal and the second responsive signal, select one of the first responsive signal and the second responsive signal based on a comparison between the first signal-to-noise ratio and the second signal-to-noise ratio, and determine a flow rate of a flow medium through the channel in the conduit according to the selected responsive signal.

2. The ultrasonic flow meter system of claim 1 , wherein the at least one second transducer is arranged on a diameter path.

3. The ultrasonic flow meter system of claim 1 , wherein the at least one second transducer comprises a plurality of second transducers each arranged to receive scattered signals from ultrasound signals transmitted by that second transducer and one or more different second transducers.

4. The ultrasonic flow meter system of claim 1 , wherein the at least one second transducer comprises three second transducers arranged on three-dimensional paths and transmitting the ultrasound signals towards one focal area.

5. The ultrasonic flow meter system of claim 1 , wherein the at least one second transducer comprises a plurality of arrays of the second transducers and each array is disposed circumferentially around the conduit and spaced from one another along the length of the conduit.

6. The ultrasonic flow meter system of claim 1 , wherein the conduit comprises a main wall and a liner attached on the main wall, and the at least one second transducer is mounted through the main wall and isolated from the channel of the conduit by the liner.

7. The ultrasonic flow meter system of claim 6 , wherein the liner comprises a non-metallic material.

8. The ultrasonic flow meter system of claim 6 , wherein the at least one pair of first transducers is mounted through the main wall and into the channel of the conduit.

9. The ultrasonic flow meter system of claim 1 , wherein the at least one pair of first transducers comprises a plurality of transit-time transducers for generating a transit-time signal.

10. The ultrasonic flow meter system of claim 1 , wherein the at least one second transducers comprises one or more Doppler transducers for generating a Doppler signal.

11. A method, comprising:

transmitting a first ultrasound signal along a chordal path through a conduit via a transmitting transducer of a first transducer pair;

generating a first responsive signal in response to the first ultrasound signal via a receiving transducer of the first transducer pair on the chordal path, the first responsive signal having a first signal-to-noise ratio;

transmitting a second ultrasound signal into the conduit via a second transducer;

generating a second responsive signal in response to a scattered signal from the second ultrasound signal via the second transducer, the second responsive signal having a second signal-to-noise ratio;

selecting one of the first responsive signal and the second responsive signal based on a comparison between the first signal-to-noise ratio and the second signal-to-noise ratio; and

determining a flow rate of a flow medium through the conduit according to the selected responsive signal.

12. The method of claim 11 , wherein transmitting the second ultrasound signal comprises transmitting the second ultrasound signal in a diameter path.

13. The method of claim 11 , further comprising receiving, via the second transducer, a plurality of the scattered signals from a plurality of the second ultrasound signals transmitted by that second transducer and one or more different second transducers.

14. The method of claim 11 , wherein transmitting the second ultrasound signal comprises transmitting a plurality of the second ultrasound signals on three-dimensional paths.

15. The method of claim 11 , wherein transmitting the second ultrasound signal comprises transmitting a plurality of the second ultrasound signals via a plurality of arrays of the second transducers, and wherein each array is disposed circumferentially around the conduit and spaced from one another along the length of the conduit.

16. The method of claim 11 , wherein the conduit comprises a main wall and a liner attached on the main wall, and the second transducer is mounted through the main wall and isolated from a channel of the conduit by the liner.

17. The method of claim 16 , wherein the liner comprises a non-metallic material.

18. The method of claim 16 , wherein the transmitting transducer and the receiving transducer of the first transducer pair are mounted through the main wall and into the channel of the conduit.

19. The method of claim 11 , wherein generating the first responsive signal comprises generating a transit-time signal in a transit-time mode.

20. The method of claim 11 , wherein generating the second responsive signal comprises generating a Doppler signal in a Doppler mode.