Method and apparatus for measuring fluid characteristics using surface generated volumetric interrogation signals
First Claim
1. Apparatus for measuring a characteristic of a fluid comprisinga solid plate-like material having a local surface and a remote surface, said remote surface being in contact with the fluid,a transducer means,means for coupling said transducer means to said local surface of said solid material,means for exciting said transducer means for generating along said local surface, Rayleigh-like surface waves having a wavelength λ
-
R in said solid material,said local surface and said remote surface having a separation, in an interrogation direction, less than four wavelengths (4λ
R), andsaid interrogation direction extending normal to said local surface.
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Accused Products
Abstract
A method and apparatus for measuring fluid characteristics use a non-invasive ultrasonic system for generating spatially extended signals into a volume of a fluid and detecting said signals for measuring the characteristic of the fluid. The generated waves are Rayleigh-like surface waves creating, in effect, an extended aperture transducer from which the waves leak into the fluid. The Rayleigh-like surface wave operates in an environment wherein the plate or other structure on which the surface wave is generated has a thickness, normal to the primary direction of propagation of the wave, of less than four Rayleigh wavelengths and greater than approximately one-half of a Rayleigh wavelength. The extended aperture has a length of at least about ten Rayleigh wavelengths. The excitation for the system is generally a short pulse interrogation in order to avoid those interferences which may cause Lamb waves to be set up in the solid material. Several different configurations employing the Rayleigh-like surface wave are illustrated and discussed.
283 Citations
40 Claims
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1. Apparatus for measuring a characteristic of a fluid comprising
a solid plate-like material having a local surface and a remote surface, said remote surface being in contact with the fluid, a transducer means, means for coupling said transducer means to said local surface of said solid material, means for exciting said transducer means for generating along said local surface, Rayleigh-like surface waves having a wavelength λ -
R in said solid material,
said local surface and said remote surface having a separation, in an interrogation direction, less than four wavelengths (4λ
R), andsaid interrogation direction extending normal to said local surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
R in said solid material,
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11. Apparatus for measuring a characteristic of a fluid comprising
a solid plate-like material having a local surface and a remote surface, said remote surface being in contact with the fluid, a transducer means, means for coupling said transducer means to said local surface of said solid material, means for exciting said transducer means for generating along said local surface, Rayleigh-like surface waves having a wavelength λ -
R in said solid material,
said local surface and said remote surface having a separation, in an interrogation direction, greater than one-half of a wavelength (λ
R /2),said interrogation direction extending normal to said local surface, and said Rayleigh-like surface waves are non-dispersive, and have an intensity at said remote surface substantially less than the intensity at the local surface. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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R in said solid material,
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20. Apparatus for measuring a characteristic of a fluid comprising
a solid plate-like material having a local surface and a remote surface, said remote surface being in contact with the fluid, a transducer means, means for coupling said transducer means to said local surface of said solid material, means for exciting said transducer means with a pulse signal sufficiently short to prevent intra-wall interference of said energy for generating along said local surface, Rayleigh-like surface waves having a wavelength λ -
R in said solid material,
said local surface and said remote surface having a separation, in an interrogation direction, less than four wavelengths (4λ
R),said interrogation direction extending normal to said local surface, and said Rayleigh-like surface waves are non-dispersive, and have an intensity at said remote surface substantially less than the intensity at the local surface. - View Dependent Claims (21)
-
R in said solid material,
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22. A clamp-on ultrasonic flowmeter for measuring a characteristic of a fluid flowing in a conduit formed with a solid material wall having a local surface and a remote surface comprising
a first and a second transducer means, means for coupling said first and second transducer means to said local surface of said conduit wall in an axially spaced relationship along said local surface of said conduit wall, means for selectively exciting said transducer means for generating, along said local surface of said conduit wall relative to said excited transducer means, Rayleigh-like surface waves having a wavelength λ -
R in said conduit wall,
said conduit having a wall thickness less than four wavelengths (4λ
R), said wall thickness being measured in a direction normal to propagation of said surface waves along said conduit.
-
R in said conduit wall,
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23. A clamp-on ultrasonic flowmeter for measuring a characteristic of fluid flowing in a conduit having a local surface and a remote surface comprising
a first and a second transducer means, means for coupling said first and second transducer means to said local surface of said conduit in an axially spaced relationship along said outside local surface of said conduit, means for selectively exciting said first and second transducer means for generating along said local surface Rayleigh-like surface waves having a wavelength λ -
R in said conduit,
said conduit having a wall thickness greater than one-half of a Rayleight wavelength (λ
R /2), andsaid Rayleigh-like surface waves being non-dispersive, and having an intensity at a conduit-fluid interface substantially less than the intensity at the local surface.
-
R in said conduit,
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24. A clamp-on ultasonic flowmeter for measuring a characteristic of a fluid flowing in a conduit having a local surface and a remote surface comprising
a first and a second transducer means, means for coupling said first and second transducer means to said local surface of said conduit in an axially spaced apart relationship along said local surface of the conduit, means for selectively exciting said first and second transducer means with a pulse signal sufficiently short to prevent intra-wall interference of said energy for generating along said local surface Rayleigh-like surface waves having a wavelength λ - R in said conduit to produce fluid characateristic measuring waves at a conduit fluid interface.
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25. A method for measuring a characteristic of a fluid comprising
contacting a remote surface of a plate-like solid material with said fluid, coupling a transducer to a local surface of a solid material for transmitting Rayleigh-like surface waves in said material, exciting said transducer for generating said Rayleigh-like surface waves having a wavelength in said material of λ -
R, and
selecting a frequency of excitation for said transducer whereby a wall thickness between the local surface and a remote surface of said solid plate-like material is less than four Rayleigh wavelengths (4λ
R). - View Dependent Claims (26, 27, 28, 29)
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R, and
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30. A method for measuring a characteristic of a fluid comprising the steps of
contacting a remote surface of a plate-like solid material with said fluid, coupling transducer to a local surface of said plate-like solid material for transmitting Rayleigh-like surface waves along said local surface, and exciting said transducer means with pulse signals sufficiently short to prevent intra-wall interference of said energy, to produce fluid characteristic interrogation waves at an interface between said plate-like sold material and said fluid.
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35. A method for measuring a characteristic of a fluid comprising the steps of
contacting a remote surface of a solid plate-like material with the fluid, coupling a transducer means to a local surface of said plate-like solid material, exciting said transducer means for generating along said local surface, Rayleigh-like surface waves having a wavelength λ -
R in said solid plate-like material, and
said Rayleigh-like surface waves are non-dispersive, and have an intensity at said remote surface of said solid material, substantially less than the intensity at the local surface. - View Dependent Claims (36, 37, 38, 39)
-
R in said solid plate-like material, and
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40. A method for measuring a characteristic of a fluid comprising the steps of
contacting a remote surface of a solid plate-like material with the fluid, coupling a transducer means to a local surface of a said solid material, exciting said transducer means with a pulse signal sufficiently short to prevent intra-wall interference of said energy for generating along said local surface, a Rayleigh-like surface wave, having a wavelength λ -
R in said solid plate-like material,
selecting a frequency of excitation for said transducer whereby said local surface and said remote surface have a separation, in an interrogation direction, greater than one half of a wavelength (λ
R /2) and less than four wavelengths (4λ
R),said interrogation direction extending normal to said local surface, and said Rayleigh-like surface wave is non-dispersive, and has an intensity at said remote surface of said solid material, substantially less than the intensity at the local surface.
-
R in said solid plate-like material,
Specification