Method and apparatus for determining a quality metric of a measurement of a fluid parameter

• US 20050159904A1
• Filed: 12/13/2004
• Published: 07/21/2005
• Est. Priority Date: 12/11/2003
• Status: Active Grant

• Current Assignee: Expro Meters, Inc. (Umbrellastream LP, Inc.)
• Original Assignee: Cidra Sarl (Nordic Cultural & Educational Foundation)
• Inventors: Davis, Michael A., Loose, Douglas H.
• Granted Patent: US 7,152,003 B2
• Time in Patent Office: Days
• US Class Current: 702/45
• CPC Class Codes: G01F 1/666 by detecting noise and sounds generated by the flowing fluid
• CPC Class Codes: G01F 1/7082 using acoustic detecting arrangements
• CPC Class Codes: G01F 1/712 using auto-correlation or cross-correlation detection means
• CPC Class Codes: G01F 1/74 Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid
• CPC Class Codes: G01F 15/024 involving digital counting

Abstract

An apparatus for measuring a parameter of a fluid passing through a pipe includes a spatial array of at least two sensors disposed at different axial locations along the pipe. Each of the sensors provides a signal indicative of unsteady pressure within the pipe at a corresponding axial location of the pipe. A signal processor constructs at least a portion of a k-ω plot using the signals and detects at least one ridge in the k-ω plot. A slope of the at least one ridge is indicative of the parameter of the fluid. The signal processor determines a quality metric by comparing an accumulated energy (power) of k-ω pairs along the at least one ridge with an accumulated energy (power) of k-ω pairs along at least one ray extending in the k-ω plot. The quality metric is indicative of a quality of the at least one ridge.

Claims

1. An apparatus for measuring a parameter of a fluid passing through a pipe, the apparatus comprising:

a spatial array of at least two sensors disposed at different axial locations along the pipe, each of the sensors providing a signal indicative of unsteady pressure within the pipe at a corresponding axial location of the pipe; and

a signal processor configured to;

construct from the signals at least a portion of a k-ω

plot, where the k-ω

plot is indicative of a dispersion relation for the unsteady pressure within the pipe,

detect at least one ridge in the k-ω

plot, a slope of the at least one ridge being indicative of the parameter of the fluid, and

compare an accumulated energy for k-ω

pairs along the at least one ridge with an accumulated energy for k-ω

pairs along at least one ray extending in the k-ω

plot to determine a quality metric indicative of a quality of the at least one ridge.

2. The apparatus of claim 1, wherein the accumulated energy for k-ω

pairs along the at least one ridge is a sum of the powers associated with the k-ω

pairs along the at least one ridge.

3. The apparatus of claim 1, wherein the accumulated energy for k-ω

pairs along the at least one ray is a sum of the powers associated with the k-ω

pairs along the at least one ray.

4. The apparatus of claim 1, wherein the accumulated energy for k-ω

pairs along the at least one ray is an average accumulated energy for k-ω

pairs along a plurality of rays.

5. The apparatus of claim 1, wherein the at least one ray has a slope indicative of a reference velocity.

6. The apparatus of claim 5, wherein the slope of the at least one ridge is indicative of a best velocity, and the reference velocity is determined as a function of the best velocity.

7. The apparatus of claim 5, wherein the slope of the at least one ridge is indicative of a best velocity, and the reference velocity is independent of the best velocity.

8. The apparatus of claim 5, wherein the signal processor is further configured to:

determine accumulated energies for a plurality of rays in the k-ω

plot, the slopes of the plurality of rays indicating a plurality of trial velocities, and

select the reference velocity from the trial velocities by comparing the accumulated energies for the plurality of rays.

9. The apparatus of claim 8, wherein the slope of the at least one ridge is indicative of a best velocity, and the trial velocities include:

a trial velocity determined as a function of the best velocity and a trial velocity independent of the best velocity.

10. The apparatus of claim 8, wherein the slope of the at least one ridge is indicative of a best velocity, and the signal processor determines the quality metric using:

11. The apparatus of claim 1, wherein the slope of the at least one ridge is indicative of a best velocity, and the signal processor determines the quality metric using:

12. The apparatus of claim 1, wherein the at least one ridge includes a first acoustic ridge in a left plane of the k-ω

plot and a second acoustic ridge in the right plane of the k-ω

plot, and the accumulated energy for k-ω

pairs along the at least one ridge is a sum of the powers associated with the k-ω

pairs along the first and second acoustic ridges.

13. The apparatus of claim 1, wherein the parameter of the fluid includes at least one of:

velocity of the fluid and speed of sound of the fluid.

14. The apparatus of claim 1 wherein the at least two pressure sensors are selected from a group consisting of:

piezoelectric, piezoresistive, strain gauge, PVDF, optical sensors, ported ac pressure sensors, accelerometers, velocity sensors, and displacement sensors.

15. The apparatus of claim 1, wherein the at least two pressure sensors are wrapped around at least a portion of the pipe and do not contact the fluid.

16. The apparatus of claim 1, wherein the signal processor is further configured to

compare the quality metric to a threshold value;

and

determine the parameter of the fluid using the slope of the at least one ridge in response to the quality metric reaching the threshold value.

17. A method for determining a quality metric of a measurement of a parameter of a fluid flowing through a pipe, the measurement being made using a spatial array of at least two sensors disposed at different axial locations along the pipe, each of the sensors providing a signal indicative of unsteady pressure within the pipe at a corresponding axial location of the pipe, the method comprising:

constructing from the signals at least a portion of a k-ω

plot, where the k-ω

plot is indicative of a dispersion relation for the unsteady pressure within the pipe;

detecting at least one ridge in the k-ω

plot, a slope of the at least one ridge being indicative of the parameter of the fluid;

comparing an accumulated energy for k-ω

pairs along the at least one ridge with an accumulated energy for k-ω

pairs along at least one ray extending in the k-ω

plot to determine a quality metric indicative of a quality of the at least one ridge.

18. The method of claim 17, wherein the accumulated energy for k-ω

pairs along the at least one ridge is a sum of the powers associated with the k-ω

pairs along the at least one ridge.

19. The method of claim 17, wherein the accumulated energy for k-ω

pairs along the at least one ray is a sum of the powers associated with the k-ω

pairs along the at least one ray.

20. The method of claim 17, wherein the accumulated energy for k-ω

pairs along the at least one ray is an average accumulated energy for k-ω

pairs along a plurality of rays.

21. The method of claim 17, wherein the at least one ray has a slope indicative of a reference velocity.

22. The method of claim 21, wherein the slope of the at least one ridge is indicative of a best velocity, and the reference velocity is determined as a function of the best velocity.

23. The method of claim 21, wherein the slope of the at least one ridge is indicative of a best velocity, and the reference velocity is independent of the best velocity.

24. The method of claim 21, further comprising:

determining accumulated energies for a plurality of rays in the k-ω

plot, the slopes of the plurality of rays indicating a plurality of trial velocities, and

selecting the reference velocity from the trial velocities by comparing the accumulated energies for the plurality of rays.

25. The method of claim 24, wherein the slope of the at least one ridge is indicative of a best velocity, and the trial velocities include:

a trial velocity determined as a function of the best velocity and a trial velocity independent of the best velocity.

26. The method of claim 24, wherein the slope of the at least one ridge is indicative of a best velocity, and the quality metric is determined using:

27. The method of claim 17, wherein the slope of the at least one ridge is indicative of a best velocity, and the quality metric is determined using:

28. The method of claim 17, wherein the parameter of the fluid includes at least one of:

velocity of the fluid and speed of sound of the fluid.

29. The method of claim 17, wherein the at least one ridge includes a first acoustic ridge in a left plane of the k-ω

plot and a second acoustic ridge in the right plane of the k-ω

plot, and the method further comprises;

summing the powers associated with the k-ω

pairs along the first and second acoustic ridges to determine the accumulated energy for the at least one ridge.

30. The method of claim 17, further comprising:

comparing the quality metric to a threshold value, and

determining the parameter of the fluid using the slope of the at least one ridge in response to the quality metric reaching the threshold value.

31. A storage medium encoded with machine-readable computer program code for measuring a parameter of a fluid passing through a pipe using a spatial array of at least two sensors disposed at different axial locations along the pipe, each of the pressure sensors providing a time-domain signal indicative of unsteady pressure within the pipe at a corresponding axial location of the pipe, the storage medium including instructions for causing a computer to implement a method comprising:

constructing from the signals at least a portion of a k-ω

plot, where the k-ω

plot is indicative of a dispersion relation for the unsteady pressure within the pipe,

detecting at least one ridge in the k-ω

plot, a slope of the at least one ridge being indicative of the parameter of the fluid,

comparing an accumulated energy for k-ω

pairs along the at least one ridge with an accumulated energy for k-ω

pairs along at least one ray extending in the k-ω

plot to determine a quality metric indicative of a quality of the at least one ridge.

32. The storage medium of claim 31, wherein the at least one ray has a slope indicative of a reference velocity, and the method further comprises:

determining accumulated energies for a plurality of rays in the k-ω

plot, the slopes of the plurality of rays indicating a plurality of trial velocities, and

selecting the reference velocity from the trial velocities by comparing the accumulated energies for the plurality of rays.

33. The storage medium of claim 32, wherein the slope of the at least one ridge is indicative of a best velocity, and the quality metric is determined using: