Flow measurement system including ultrasonic transducers
First Claim
1. A sensing system for detection of an ultrasonic interrogation signal transmitted through a gaseous fluid to determine a characteristic of the fluid, such sensing system comprisinga receiving sensor includinga body for holding a plurality n of ultrasonic transducer elements, said body being mounted in use to orient each of the transducer elements toward the fluid,said plurality n of ultrasonic transducer elements mounted in said body, wherein n>
- 2, each respective element of the n ultrasonic transducer elements having a face for directly coupling energy between said respective element and fluid along an axis of signal propagation,said transducer elements mounted in the body operating at a frequency having a characteristic ultrasonic wavelength λ
in the fluid, and being arranged in pairs, each element of a pair having its face offset a distance λ
/2 along it axis of propagation from the face of the other element of the pair.
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Abstract
A sensor system includes an ultrasonic transducer head with plural transducing elements. The elements are arranged in pairs with the first one of each pair lying in a first plane and the second one of each pair in a second plane spaced a half wavelength away. For transmission, the two are driven out of phase, while for reception their outputs are combined differentially. By changing the drive frequency the transmitted beam is steered to compensate for changes in transducer alignment, or changes in acoustic path caused by abnormal temperature, pressure or flow velocity. In another embodiment, an assembly has a plurality of transducers aligned along slightly divergent paths. Preferred systems employ an upstream and a downstream transducer assembly, each of which is used to alternately transmit and receive signal energy.
22 Citations
20 Claims
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1. A sensing system for detection of an ultrasonic interrogation signal transmitted through a gaseous fluid to determine a characteristic of the fluid, such sensing system comprising
a receiving sensor including a body for holding a plurality n of ultrasonic transducer elements, said body being mounted in use to orient each of the transducer elements toward the fluid, said plurality n of ultrasonic transducer elements mounted in said body, wherein n> - 2, each respective element of the n ultrasonic transducer elements having a face for directly coupling energy between said respective element and fluid along an axis of signal propagation,
said transducer elements mounted in the body operating at a frequency having a characteristic ultrasonic wavelength λ
in the fluid, and being arranged in pairs, each element of a pair having its face offset a distance λ
/2 along it axis of propagation from the face of the other element of the pair. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
- 2, each respective element of the n ultrasonic transducer elements having a face for directly coupling energy between said respective element and fluid along an axis of signal propagation,
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20. An ultrasonic transducer system for gas flow interrogation, such system comprising a body having a surface facing the gas and a plurality ultrasonic of transducing elements extending from the surface toward the gas, each element being oriented by said body to transduce ultrasonic energy directly in said gas along a different axis, offset slightly in direction from a common central axis of said transducing elements, and at least one pair of said elements including a first element and a second element having faces which are positioned offset from each other by a distance along said central axis equal to a half wavelength of said ultrasonic energy in the gas.
Specification