Abstract: A sensor apparatus is provided for measuring within a region of a conduit for guiding a flow. The apparatus includes a transducer arrangement disposed at least partially around an external surface of a wall of the conduit and having one or more driver elements for exciting in operation a helical acoustic wave propagation within the wall of the conduit for leaking acoustical energy from the helical acoustic wave propagation over an extensive area of the wall of the conduit for stimulating waves in chordal paths within the flow, wherein the waves in the choral paths within the flow reenter the wall of the conduit to propagate further as a guided helical wave. The transducer arrangement includes one or more sensors for receiving a re-entered portion of the acoustic wave propagation along the paths within the flow which interacts with the flow and includes information characterizing properties of the flow.

Abstract: A sensor apparatus is provided for measuring within a region of a conduit for guiding a flow. The apparatus includes a transducer arrangement disposed at least partially around an external surface of a wall of the conduit and having one or more driver elements for exciting in operation a helical acoustic wave propagation within the wall of the conduit for leaking acoustical energy from the helical acoustic wave propagation over an extensive area of the wall of the conduit for stimulating waves in chordal paths within the flow, wherein the waves in the choral paths within the flow reenter the wall of the conduit to propagate further as a guided helical wave. The transducer arrangement includes one or more sensors for receiving a re-entered portion of the acoustic wave propagation along the paths within the flow which interacts with the flow and includes information characterizing properties of the flow.

Abstract: A sensor apparatus is provided for measuring within a region of a conduit for guiding a flow. The apparatus includes a transducer arrangement disposed at least partially around an external surface of a wall of the conduit and having one or more driver elements for exciting in operation a helical acoustic wave propagation within the wall of the conduit for leaking acoustical energy from the helical acoustic wave propagation over an extensive area of the wall of the conduit for stimulating waves in chordal paths within the flow, wherein the waves in the choral paths within the flow re-enter the wall of the conduit to propagate further as a guided helical wave. The transducer arrangement includes one or more sensors for receiving a re-entered portion of the acoustic wave propagation along the paths within the flow which interacts with the flow and includes information characterizing properties of the flow.

Abstract: A sensor apparatus is provided for measuring characteristics of a wall of a structure and/or a medium in contact with the structure, wherein the sensor apparatus includes a transducer arrangement disposed at least partially around a planar or curved surface of a wall of the structure, or disposed over a region of a planar or curved surface of a wall of the structure. The sensor apparatus includes a transducer waveguide including at least one free distal end whereat one or more driver and/or receiver elements are mounted on one or more sides of the at least one free distal end. Moreover, the transducer arrangement is operable, when interrogating the structure to perform at least one of: switching between selected acoustic wave modes present in an acoustic wave propagation, steering an acoustic propagation direction of the acoustic wave propagation.

Abstract: A flow measuring apparatus measures a fluid flow within a conduit including a wall. The apparatus includes a transducer arrangement including at least two transducers for alternately emitting and receiving ultrasonic radiation through the conduit wall and the flow. The apparatus also includes a signal processing arrangement for generating signals to excite the transducer arrangement and for processing received signals provided by the transducer arrangement for generating output signals from the signal processing arrangement indicative of properties of the flow. The transducer arrangement in cooperation with the conduit provides a first path for Lamb-wave ultrasonic radiation coupling directly from a first of the at least two transducers, to a second of said at least two transducers to generate a first received signal.

Abstract: A flow measuring apparatus (300, 500) measures a fluid flow (130) within a conduit (120) including a wall (110). The apparatus (300, 500) includes a transducer arrangement including at least two transducers (100A, 100B) for alternately emitting and receiving ultrasonic radiation through the conduit wall (110) and the flow (130). The apparatus (300, 500) also includes a signal processing arrangement (310) for generating signals to excite the transducer arrangement (100A, 100B) and for processing received signals provided by the transducer arrangement (100A, 100B) for generating output signals from the signal processing arrangement (310) indicative of properties of the flow. The transducer arrangement (100A, 100B) in cooperation with the conduit (120) provides a first path (200) for Lamb-wave ultrasonic radiation coupling directly from a first of the at least two transducers (100A, 100B), to a second of said at least two transducers to generate a first received signal.