Panametrics, Inc.

Other

General Electric Company

Exxon Research and Engineering Company

Lfe Corporation

Elster Nv/sa

Lawrence C Lynnworth

Yi Liu

James E Matson

James E Bradshaw

Leonard D Braswell

Jack W Smalling

Toan Huu Nguyen

James M Korba

Haim H Bau

Norman E Pedersen

Jeffrey Tilden

Saul A Jacobson

Kenneth A Fowler

Dana R Patch

David R Wallace

Christopher Smart

Jin O Kim

Steven A Lynnworth

Thomas Nicholson

Christopher C Doyle

John L Seger

A steerable acoustic waveguide apparatus includes plural plates arranged in one or more linear arrays. Steering of an acoustic beam radiated from the waveguide apparatus may be achieved through differential delays of acoustic signals resulting from differences in timing, frequency, or mode or resulting from differences in physical attributes of the plates. In one aspect, where the apparatus is used with a target that is confined by a conduit such as a pipe, a longitudinal plane for the conduit intersects the linear array, an array plane for the linear array has a conduit orientation relative to the longitudinal plane, and the conduit orientation is substantially perpendicular or substantially parallel. The waveguide apparatus may serve as a thermal buffer and may simplify access to an acoustic path in a device such as an ultrasonic flowmeter.

Steerable acoustic waveguide

An apparatus for determining a characteristic for a fluid in a tube, the apparatus including a force applying system to cause a change in a transverse dimension of a segment of the tube, wherein the change in the transverse dimension is reversible, and an ultrasonic system that comprises a single transducer for launching and receiving ultrasonic signals. Ultrasonic signals propagate through the tube along colinear paths of different lengths that are orthogonal to the tube wall. At least one of the paths is located entirely within the segment. Each of the ultrasonic signals propagates through the tube wall in a first wall region and reflects from an inner surface of a second wall region. Path length differences between the paths are determined, and transit times are determined for each of the ultrasonic signals. The characteristic is determined based on information including the path length differences and the transit times.

Noninvasive measurement of fluid characteristics using reversibly deformed conduit

The mass flow rate sensor includes a waveguide disposed in a flow passage having a bluff body facing in an upstream direction. Waves are pulsed along the waveguide for interaction with the fluid. A receiver is coupled to the waveguide to detect a propagated wave and provides a first output signal proportional to the transit time of the propagated wave for determining fluid density. The receiver also provides a second output signal proportional to the shedding frequency of vortices from the waveguide to determine velocity. An electronics module calculates mass flow rate from the velocity times density times area of the flow passage and a constant. In other forms, the velocity is ascertained by transmitting an ultrasonic beam through the shedding vortices to determine vortex frequency which is proportional to velocity.

Mass flow sensor and methods of determining mass flow of a fluid

An acoustic waveguide system including a waveguide, a housing with a port in one side of the housing for receiving the proximal end of the waveguide, the port opening into a channel in the housing. A first shear transducer is located in the channel of the housing and disposed on the waveguide, and a second shear transducer is located in the channel and disposed on the opposite side of the waveguide. The first and second transducers are configured to launch a torsional or an extensional wave in the waveguide depending on the orientation and polarity of the transducers.

Acoustic waveguide system

A method of and system for analyzing the mass flow rate of a fluid flowing in a conduit wherein ultrasonic energy is transmitted along multiple v paths in multiple parallel quadrature planes through the fluid, the transit time of the ultrasonic energy through the fluid with and against the flow direction of the fluid is measured, and the flow velocity of the fluid in each quadrature plane is calculated based on the transit time in each quadrature plane. The density of the fluid in each quadrature plane is then determined and quadrature integration of the product of the fluid density and fluid velocity in each quadrature plane is performed to calculate the total mass flow rate of the fluid more accurately by eliminating errors associated with assuming that the density of the fluid in the conduit is uniform.

Method of and system for determining the mass flow rate of a fluid flowing in a conduit

An ultrasonic coupling assembly includes a barrier layer that contacts the wall, and a generally thicker layer formed of a compliant material such as zinc foil that extends over the first layer. A third layer may cover and enclose the compliant layer, e.g., by folding the first layer over and on top of the second layer to cover the edge faces thereof. An exemplary embodiment is implemented using gold foil approximately one mil thick for the first layer, and zinc sheeting approximately four mils thick for the second layer. Use of inert top and bottom, or outside, layers prevents the inadvertent installation of the coupling element with the compliant layer directly contacting the wall. Disk embodiments may employ a stack of separate disks formed of foils or sheets of the respective materials. For cryogenic applications, a material such as indium may be used for the second layer without risk of its alloying or migration through the first layer.

Layered ultrasonic coupler

An encapsulated or rigid bundle of rods forms a substantially non-dispersive buffer usable in extreme environments, operable over wide bandwidth, and repairable in the field. The rigid assembly extends through a nozzle or flanged pipe penetration to launch its signals directly in the fluid at a defined angle. The bundles are non-degrading wave guides to carry signals through degrading environments. This is useful for numerous stack, freestream and chordal path configurations, as well as clamp-on systems and special mode-converting configurations. Beam shaping and steering may be passively effected with patterned bundle constructions, and plural faces, which may be stepped or angled, may define multiple oblique, reflective or different length paths while mounted in spoolpieces at normal incidence.

Ultrasonic path bundle and systems

An ultrasonic system employs a path through a fluid to determine fluid density by a differential reflection coefficient measurement of fluid impedance Z and a fluid sound speed c. Preferred configurations use clamp-on (external) transducers and combine ultrasonic measurements of flow velocity V over one or more paths, to obtain the mass flow rate. Z is determined by comparing reflections from a reference target, which may be totally reflective, with reflections from a sensor target having an effectively lower Z, which may be close to that of the fluid. Both targets are preferably located to be cleaned by the natural flow of the fluid. The low-Z target is interrogated at least once. Vee blocks provide a compact combination of reference and sensor targets that can be integrated with a velocity-sensing flowcell. Folded-path flow cells compactly measure V alone or in combination with density. The principal surface may be aligned parallel to the free stream direction and located to yield a flow value substantially equal to the area averaged flow, and the system may further correct for variations in the vicinity of the reflector.

Stream-cleaned differential reflection coefficient sensor

A waveguide couples ultrasonic energy from a source on one side of a fluid-bounding wall, such as a conduit, into fluid on the other side of the wall. The waveguide has a buffer that couples to the source, and a seat with an exit face, while an intermediate portion contains a redirecting surface for internally redirecting energy propagated along the buffer toward the exit face to exit as a narrow directed beam. The waveguide core has a rectangular cross section which is narrow, i.e., has an aspect ratio above two and preferably above three or four, while the buffer has a length effective to thermally isolate or protect the source from the conduit. The waveguide attaches easily, either as a clamp-on or welded unit, to a pipe or spoolpiece, allowing local fabrication of massive or custom flow cells, such as large spoolpieces with Gauss-Chebyshev interrogation paths. Several guides may be positioned in an array to cover interrogation paths for an extended range of sound speeds or flow rates. In one embodiment the redirecting face may be curved, or stepped at different angles, to provide output beams at several or a continuum of exit angles. A low sound speed material may be added to control the refraction angle of the exit beam in the wall or fluid. The construction readily adapts to wetted systems. The waveguide may have the overall shape of a hockey stick, with the buffer and the seat lying in a common plane, or one may curve into, or join at an angle, the other. Features such as holes, notches or the like may provide reference echoes for a flow meter to automatically calculate temperature-dependent transit time corrections for the buffer, and additional reflective surfaces or topological features such as holes may redirect echoes or noise out of the measurement path. In one embodiment, the buffer is a thin tube which couples shear waves into the seat portion, which has a rectangular cross section.

Ultrasonic buffer/waveguide

An encapsulated or rigid bundle of rods forms a substantially non-dispersive buffer usable in extreme environments, operable over wide bandwidth, and in some implementations, easily repairable in the field. In one preferred configuration, suitable for measuring the flow of low-molecular-weight gases over a wide range of pressure, temperature and flow rates, the bundle is made of about one thousand stainless steel welding rods tightly packed inside a 1-inch diameter tube. The rigid encapsulated assembly is sealed at the end that is in contact with the gas and may be sealed into a high-pressure flange in a manner that yields broadband transmission characteristics. A second buffer bundle, aligned with the first bundle, may be pressure-coupled on the other side of the flange. Ultrasonic pulses transmitted into the first bundle remote from the gas are transmitted with little loss and little pulse distortion into the gas, while the transducer is thermally isolated by the second bundle and remains near ambient temperature. The high-pressure flange is thinned locally over a central area yet supports the rod safely and withstands pressures of 300 bar. This locally-thin region supports and aligns both buffers, while transmitting a broad band-width pulse in the preferred axial direction, while discouraging transmission in all other directions. This helps reduce solid-body-borne crosstalk and results in a high signal-to-noise ratio and high accuracy in the measurement of flow or other measurands. Signals may be combined to remove noise and then be processed to compute flow-related terms. The bundles are non-degrading waveguides to carry signals through degrading environments. This is useful for numerous stack, freestream and chordal path configurations, as well as clamp-on systems and special mode-converting configurations. Beam shaping and steering may be passively effected with patterned bundle constructions.

Transducers are mounted in a housing or vessel to propagate signals along a fluid measurement path, and a plurality of massive elements are placed between transmitting and receiving transducers in the acoustic propagation path through the solid body of the housing or vessel to remove crosstalk. In a preferred embodiment, the elements are rings, or sleeves which are attached to, or are machined from a thicker cylinder to leave a thin-walled cylinder with alternating masses. An isolation structure lightly sandwiches a flange between O-rings. This structure may be formed with flanged transducer casings, allowing the transducers to be closely spaced in solid conduits or on rigid frames without ringing. Alternatively, it may be formed in a separate framework or holder, providing precise positioning for interrogating gases in unconfined or loosely confined regions. Closed path sensor configurations measure circulation or swirl.

Ultrasonic transducer system with crosstalk isolation

A sensing system detects elastic waves propagated along a sensing path in a sheet to detect a characteristic of material contacting the other side of the sheet. An acoustic load applied between transducers discriminates characteristics in diverse environments. Different systems detect density, stiffness, presence, degree of coupling, thickness, or fill height of the material, with applications to areas as diverse as aircraft wing ice measurement, storage tank fill height detection, and mass flow detection. In one preferred embodiment a protective housing covers and protects the first side of the sheet over a region of the sheet encompassing the sensing path, and may secure transducers in defined positions. The housing preferably defines a closed reservoir that is temporarily filled to determine a normative measurement such as transit time or change in phase velocity. The normative measurement provides an empirical calibration that, in turn, allows a final parameter or a detection threshold to be precisely determined.

Elastic wave sensing system

An apparatus and method for measuring gas flow velocity through a high stack employs ultrasonic transducers. The transducers are placed on opposite ends of a diameter several hundred feet up, with a small vertical separation L between the transducers. Apparatus for measuring acoustic velocity in the stack gas over short path lengths is also included.

Process and apparatus for ultrasonic measurement of volumeric flow

Transducers are mounted in a housing or vessel to propagate signals along a fluid measurement path, and received signals are temporally separated to remove crosstalk in the acoustic propagation paths of interest, which may be paths through the solid body of the housing or vessel or may be separate paths. These may be segments in a closed path circulation or swirl measurement, or different paths carrying combinations of possibly unrelated measurement signals. In a preferred embodiment, a single channel instrument processes signals from plural transducers which are connected in parallel to its processing input, greatly enhancing the effective system bandwidth and reducing equipment costs. Clamp-on circulation measurement or detection systems are described that allow easy evalution and set-up of flow conditioning loops.

Ultrasonic transducer system with temporal crosstalk isolation

Transducers are mounted in a housing or vessel to propagate signals along a fluid measurement path, and a plurality of massive elements are placed between transmitting and receiving transducers in the acoustic propagation path through the solid body of the housing or vessel to remove crosstalk. In a preferred embodiment, the elements are rings, which are attached to, or are machined from a thicker cylinder to leave a thin-walled cylinder that holds the transducer off from a conduit wall. Preferably the rings are closely spaced or contiguous, but contact each other only along a small point-like region, so that substantially all ringing acoustic energy flows to the rings via the thin-walled stand-off. In one embodiment, a thick-walled tube is formed with plural radially oriented slots to yield an equivalent structure of alternating masses. In a related embodiment, inner and outer thick-walled tubes so formed are joined at one end to provide a longer path. For measuring stack gases, the isolated transducer stand-off fits within a sleeve that channels purge gas to prevent excessive heating and prevent fouling. Different mounting systems provide high signal strength with varying amounts of crosstalk as the pressure varies.

Growing community of inventors

Waltham, MA, United States of America

Lawrence C Lynnworth