Ultrasonic flowmeter and method for measuring flow

Patent metadata

Field	Value
Publication number	US-9816847-B2
Application number	US-201514844745-A
Country	US
Kind code	B2
Filing date	Sep 3, 2015
Priority date	Sep 5, 2014
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

An ultrasonic flow meter that includes a first ultrasonic transducer for making incident a first ultrasonic signal against a pipe through which a fluid flows; a second ultrasonic transducer, disposed in a position capable of receiving the first ultrasonic signal, for making incident a second ultrasonic signal against pipe; a flow velocity computation component for computing the flow velocity of the fluid within pipe based on a first time period during which the first ultrasonic signal arrives at the second ultrasonic transducer and on a second time period during which the second ultrasonic signal arrives at the first ultrasonic transducer; a logarithmic correction function saving component for saving a logarithmic correction function; and a logarithmic correction component for correction the flow velocity by using the correction coefficient that corresponds to the Reynolds number of the fluid.

First claim

The invention claimed is:

1. An ultrasonic flow meter comprising:
a first ultrasonic transducer for making incident a first ultrasonic signal against a pipe through which a fluid flows;
a second ultrasonic transducer, disposed in a position capable of receiving said first ultrasonic signal, for making incident a second ultrasonic signal against said pipe;
a flow velocity computation component for computing a flow velocity of the fluid within said pipe based on a first time period during which said first ultrasonic signal passes through said pipe and arrives at said second ultrasonic transducer and on a second time period during which said second ultrasonic signal passes through said pipe and arrives at said first ultrasonic transducer;
a logarithmic correction function saving component for saving a logarithmic correction function that has performed broken-line approximation of a relationship between a logarithm of a Reynolds number and a correction coefficient for said flow velocity; and
a logarithm implementing correction component for correcting said flow velocity by using the correction coefficient that corresponds to said logarithm of the Reynolds number of the fluid,
wherein the logarithmic correction function is obtained by connecting a plurality of logarithms of Reynolds numbers and points indicating a combination of actual measured values of the correction coefficient corresponding thereto within a predetermined error range of an approximation line.

2. An ultrasonic flow meter according to claim 1 , further comprising a logarithmic correction function creation component for receiving a multiplicity of combinations of a Reynolds number and a correction coefficient and for creating said logarithm implementing correction function.

3. An ultrasonic flow meter according to claim 1 , further comprising a logarithmic correction function creation component for receiving a multiplicity of combinations of the logarithm of a Reynolds number and a correction coefficient and for creating said logarithmic correction function.

4. An ultrasonic flow meter according to claim 1 , in which said first ultrasonic transducer comprises a first oscillator for emitting said first ultrasonic signal, and a first wedge for being disposed on said pipe so that said first ultrasonic signal will be made obliquely incident against said pipe.

5. An ultrasonic flow meter according to claim 1 , in which said second ultrasonic transducer comprises a second oscillator for emitting said second ultrasonic signal, and a second wedge for being disposed on said pipe so that said second ultrasonic signal will be made obliquely incident against said pipe.

6. An ultrasonic flow meter according to claim 1 , in which said flow velocity computation component computes the flow velocity of the fluid within said pipe based on an angle of emission of said first and second ultrasonic signals emitted from a pipe wall of said pipe to a cavity of said pipe.

7. An ultrasonic flow meter according to claim 6 , in which the angle of emission of said first ultrasonic signal emitted from the pipe wall of said pipe to the cavity of said pipe is computed based on an angle of incidence of the first ultrasonic signal from said first ultrasonic transducer to said pipe, an acoustic velocity of said first ultrasonic signal at said first ultrasonic transducer, and the acoustic velocity of said first ultrasonic signal at the fluid flowing through said cavity.

8. An ultrasonic flow meter according to claim 6 , in which the angle of emission of said second ultrasonic signal emitted from the pipe wall of said pipe to the cavity of said pipe is computed based on an angle of incidence of the second ultrasonic signal from said second ultrasonic transducer to said pipe, an acoustic velocity of said second ultrasonic signal at said second ultrasonic transducer, and the acoustic velocity of said second ultrasonic signal at the fluid flowing through said cavity.

9. A method for measuring flow that includes:
making incident a first ultrasonic signal from a first ultrasonic transducer against a pipe through which a fluid flows;
making incident a second ultrasonic signal from a second ultrasonic transducer, disposed in a position capable of receiving said first ultrasonic signal, against said pipe;
computing a flow velocity of the fluid within said pipe based on a first time period during which said first ultrasonic signal passes through said pipe and arrives at said second ultrasonic transducer and on a second time period during which said second ultrasonic signal passes through said pipe and arrives at said first ultrasonic transducer;
preparing a logarithmic correction function that has performed broken-line approximation of a relationship between a logarithm of a Reynolds number and a correction coefficient for said flow velocity; and
correcting said flow velocity by using said correction coefficient that corresponds to the logarithm of the Reynolds number of said fluid,
wherein the logarithmic correction function is obtained by connecting a plurality of logarithms of Reynolds numbers and points indicating a combination of actual measured values of the correction coefficient corresponding thereto within a predetermined error range of an approximation line.

10. A method for measuring flow according to claim 9 that further includes creating said logarithmic correction function based on a multiplicity of combinations of a Reynolds number and of a correction factor.

11. A method for measuring flow according to claim 9 that further includes creating of said logarithmic correction function based on a multiplicity of combinations of the logarithm of a Reynolds number and of a correction factor.

12. A method for measuring flow according to claim 9 , in which said first ultrasonic transducer comprises a first oscillator for emitting said first ultrasonic signal, and a first wedge for being disposed on said pipe so that said first ultrasonic signal will be made obliquely incident against said pipe.

13. A method for measuring flow according to claim 9 , in which said second ultrasonic transducer comprises a second oscillator for emitting said second ultrasonic signal, and a second wedge for being disposed on said pipe so that said second ultrasonic signal will be made obliquely incident against said pipe.

14. A method for measuring flow according to claim 9 , in which the flow velocity of the fluid within said pipe is computed based on an angle of emission of said first and second ultrasonic signals emitted from a pipe wall of said pipe to a cavity of said pipe.

15. A method for measuring flow according to claim 14 , in which the angle of emission of said first ultrasonic signal emitted from the pipe wall of said pipe to the cavity of said pipe is computed based on an angle of incidence of the first ultrasonic signal from said first ultrasonic transducer to said pipe, an acoustic velocity of said first ultrasonic signal at said first ultrasonic transducer, and the acoustic velocity of said first ultrasonic signal at the fluid flowing through said cavity.

16. A method for measuring flow according to claim 14 , in which the angle of emission of said second ultrasonic signal emitted from the pipe wall of said pipe to the cavity of said pipe is computed based on an angle of incidence of the second ultrasonic signal from said second ultrasonic transducer to said pipe, an acoustic velocity of said second ultrasonic signal at said second ultrasonic transducer, and the acoustic velocity of said second ultrasonic signal at the fluid flowing through said cavity.

Assignees

• Azbil Corp

Inventors

• Sasaki Hiroshi

Classifications

• G01F25/0053

  Physics · mapped topic

• G01F15/063

  using electrical means · CPC title

• G01F1/667 Primary

  Arrangements of transducers for ultrasonic flowmeters; Circuits for operating ultrasonic flowmeters · CPC title

• G01F25/15

  specially adapted for gas meters (G01F25/11 - G01F25/14, G01F25/17 take precedence) · CPC title