Ultrasonic flow rate measurement method and system

1. A method of determining the flow rate of a fluid in a conduit, the method comprising:

directing ultrasonic energy through the conduit and fluid along multiple paths;

detecting and measuring the ultrasonic energy using a range gated Doppler technique to determine the velocity of the fluid at several points in the fluid in the conduit; and

determining, from the several point velocities, the average flow rate of the fluid in the conduit, wherein the determination of the average flow rate includes multiplying each of the point velocities by a predetermined weighting factor and summing the weighted point velocities, each weighting factor for each point velocity being a function of the position of the point in the fluid in the conduit.

2. The method of claim 1 in which the ultrasonic energy is directed along diameter paths through the conduit and the fluid.

3. The method of claim 1 in which determining the volumetric flow rate includes multiplying the summation by the area of the conduit.

4. The method of claim 1 in which measuring includes determining the point velocities at the center of the fluid in the conduit and at least one point in each quadrant of the fluid in the conduit.

5. The method of claim 4 in which at least seven point velocities are measured.

6. The method of claim 1 in which directing includes employing transducers clamped on the outside of the conduit.

7. The method of claim 6 in which the transducers are in pairs, the transducers of each pair on opposite sides of the conduit.

8. The method of claim 7 in which there are three pairs of transducers.

9. The method of claim 1 in which directing ultrasonic energy includes employing wetted transducers.

10. A fluid flow rate measurement system comprising:

an ultrasonic transducer subsystem configured to direct and measure ultrasonic energy through a conduit fluid flow therein along multiple paths and to determine the velocity of the fluid at several points in the fluid in the conduit using a range gated Doppler technique; and

an electronic subsystem, responsive to the ultrasonic transducer subsystem, configured to determine, from the several point velocities, the average flow rate of the fluid in the conduit, wherein the electronic subsystem is configured to multiply each of the point velocities by a stored weighting factor and to sum the weighted point velocities, each stored weighting factor for each point velocity being a function of the position of the point in the fluid in the conduit.

11. The system of claim 10 in which the transducers are arranged to direct ultrasonic energy along diameter paths through the conduit and the fluid.

12. The system of claim 10 in which the transducers are arranged to include directing ultrasonic energy along chordal paths through the conduit and the fluid.

13. The system of claim 10 in which the electronic subsystem is configured to multiply the summation by the cross-sectional area of the conduit and to output the multiple as a volumetric flow rate.

14. The system of claim 10 in which the ultrasonic transducer subsystem is configured to determine the point velocities at the center of the fluid in the conduit and at least one point in each quadrant of the fluid in the conduit.

15. The system of claim 14 in which at least seven point velocities are measured.

16. The system of claim 10 in which the transducers of the ultrasonic transducer subsystem are clamped on the outside of the conduit.

17. The system of claim 16 in which the transducers are in pairs, the transducers of each pair on opposite sides of the conduit.

18. The system of claim 17 in which there are three pairs of transducers.

19. The system of claim 16 in which the transducers are in pairs, the transducers of each pair on the same side of the conduit.

20. The system of claim 10 in which the transducers of the ultrasonic transducer subsystem are wetted transducers.

21. A method of determining the volumetric flow rate of a fluid in a conduit, the method comprising:

detecting the velocity of the fluid at several points in the fluid in the conduit; and

determining, from the several point velocities, the volumetric flow rate of the fluid in the conduit by multiplying each of the point velocities by a predetermined weighting factor, summing the weighted point velocities, and multiplying the summation by the area of the conduit, wherein the ultrasonic energy is directed along diameter paths through the conduit and the fluid, and wherein each weighting factor for each point velocity is a function of the position of the point in the fluid in the conduit.

22. The method of claim 21 in which the point velocities are determined by directing ultrasonic energy through the conduit and the fluid along multiple paths and detecting and measuring the ultrasonic energy using a range gated Doppler technique.

23. The method of claim 22 in which the ultrasonic energy is directed along chordal paths through the conduit and the fluid.

24. The method of claim 22 in which directing includes employing transducers clamped on the outside of the conduit.

25. The method of claim 24 in which the transducers are in pairs, the transducers of each pair on opposite sides of the conduit.

26. The method of claim 25 in which there are three pairs of transducers.

27. The method of claim 22 in which directing includes employing wetted transducers.

28. The method of claim 21 in which measuring includes determining the point velocities at the center of the fluid in the conduit and at least one point in each quadrant of the fluid in the fluid in the conduit.

29. The method of claim 28 in which there are at least seven point velocities measured.

30. A fluid flow rate measurement system comprising:

a measurement subsystem configured to determine the velocity of the fluid flow at least two points in the fluid in the conduit; and

an electronic subsystem responsive to the measuring subsystem and configured to determine, from the several point velocities, the flow rate of the fluid in the conduit,

wherein the measurement subsystem includes an ultrasonic transducer arrangement configured to direct and measure ultrasonic energy through the conduit and the fluid along multiple paths to determine the velocity of the fluid at several points in the fluid in the conduit using a range gated Doppler technique, and wherein determining the average flow rate includes multiplying each of the point velocities by a predetermined weighting factor and summing the weighted point velocities, each weighting factor for each point velocity being a function of the position of the point in the fluid in the conduit.

31. The system of claim 30 in which the ultrasonic energy is directed along diameter paths through the conduit and the fluid.

32. The system of claim 30 in which determining the volumetric flow rate includes multiplying the summation by the area of the conduit.

33. The system of claim 30 in which measuring includes determining the point velocities at the center of the fluid in the conduit and at least one point in each quadrant of the fluid in the conduit.

34. The system of claim 33 in which at least seven point velocities are measured.

35. The system of claim 30 in which the ultrasonic transducer arrangement includes transducers clamped on the outside of the conduit.

36. The system of claim 35 in which the transducers are in pairs, the transducers of each pair on opposite sides of the conduit.

37. The system of claim 36 in which there are three pairs of transducers.

38. The system of claim 35 in which the transducers are in pairs, the transducers of each pair on the same side of the conduit.