Method and apparatus for ultrasonic doppler velocimetry using speed of sound and reflection mode pulsed wideband doppler

• US 6,067,861 A
• Filed: 06/18/1998
• Issued: 05/30/2000
• Est. Priority Date: 06/18/1998
• Status: Expired due to Fees

• Current Assignee: Battelle Memorial Institute
• Original Assignee: Battelle Memorial Institute
• Inventors: Shekarriz, Alireza, Sheen, David M.
• Primary Examiner(s): Fuller, Benjamin R.
• Assistant Examiner(s): PATEL, JAGDISH C
• Application Number:
  US09/100,293
• Time in Patent Office: 712 Days
• Field of Search: 73/861.27, 73/861.25, 73/861.26, 73/861.28, 73/861.29, 73/861.31, 73/861.18, 73/861.05, 73/861.04, 73/861, 73/597, 600/455, 600/456, 600/454, 367/89, 367/90
• US Class Current: 73/861.25
• CPC Class Codes: G01F 1/663 by measuring Doppler frequency shift
• CPC Class Codes: G01F 1/666 by detecting noise and sounds generated by the flowing fluid
• CPC Class Codes: G01F 1/667 Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters
• CPC Class Codes: G01F 1/668 Compensating or correcting for variations in velocity of sound
• CPC Class Codes: G01N 2291/02836 Flow rate, liquid level

Abstract

According to the present invention, a method and apparatus rely upon tomographic measurement of the speed of sound and fluid velocity in a pipe. The invention provides a more accurate profile of velocity within flow fields where the speed of sound varies within the cross-section of the pipe. This profile is obtained by reconstruction of the velocity profile from the local speed of sound measurement simultaneously with the flow velocity. The method of the present invention is real-time tomographic ultrasonic Doppler velocimetry utilizing a to plurality of ultrasonic transmission and reflection measurements along two orthogonal sets of parallel acoustic lines-of-sight. The fluid velocity profile and the acoustic velocity profile are determined by iteration between determining a fluid velocity profile and measuring local acoustic velocity until convergence is reached.

Claims

1. A method of measuring a velocity profile of a fluid flow having an ultrasonic scatterer, the method comprising the steps of:

(a) providing at least one pair of ultrasonic transducers surrounding said fluid flow;

(b) measuring a time of flight between said at least one pair of ultrasonic transducers;

(c) measuring a reflection mode pulsed wideband Doppler between at least one transducer of said at least one pair of ultrasonic tranducers and said ultrasonic scatterer;

(d) mathematically reconstructing a local speed of sound across a flow section from the time of flight; and

(e) mathematically reconstructing a local fluid velocity from a combination of the local speed of sound and the reflection mode pulsed wideband Doppler, thereby obtaining the velocity profile.

2. The method as recited in claim 1, further using a plurality of ultrasonic cycles in said step of measuring of a reflection mode pulsed wideband Doppler.

3. The method as recited in claim 2, further providing 5 to 20 pulses of said plurality of ultrasonic cycles.

4. The method as recited in claim 1, further varying a density of said ultrasonic scatterer.

5. An apparatus for measuring a velocity profile of a fluid flow having an ultrasonic scatterer, the apparatus comprising:

(a) at least one pair of ultrasonic transducers surrounding said fluid flow, said at least one pair of ultrasonic transducers used in measuring a time of flight between said at least one pair of ultrasonic transducers, and a reflection mode pulsed wideband Doppler being measured between at least one transducer of said at least one pair of ultrasonic transducers and said ultrasonic scatterer; and

(b) an ultrasonic Doppler computer data collection system connected to said at least one pair of ultrasonic transducers, said ultrasonic Doppler computer data collection system including a computer system, said computer system having a first instruction set for mathematically reconstructing a local speed of sound across a flow section from the time of flight, and having a second instruction set for mathematically reconstructing a local fluid velocity from a combination of the local speed of sound and the reflection mode pulsed wideband Doppler, thereby obtaining the velocity profile.

6. The apparatus as recited in claim 5, wherein said ultrasonic Doppler computer data collection system includes a transceiver coupled between said at least one pair of ultrasonic transducers and the computer system, said transceiver transmitting a plurality of ultrasonic cycles.

7. The apparatus as recited in claim 6, wherein said plurality of ultrasonic cycles is from 5 to 20 pulses.

8. The apparatus as recited in claim 5, wherein said ultrasonic scatterer is a variation in density.