Abstract: A fluid sensor, and associated monitoring and control system, employing a cylindrical venturi to eliminate stratification of fluid passing therethrough, and a capacitive sensor operatively coupled with the cylindrical venturi to facilitate the sensing of the fluid while in the venturi.

Abstract: The present invention provides methods for determining a parameter associated with a flow of a fluid located within a fluid conduit, based on measuring the difference between electrical signals of at least two second sensing elements contacting different positions on am exterior of the fluid conduit. The sensing elements comprise an assembly of nanoparticles being in electric contact with conductive electrodes; wherein the electrical signals of the sensing elements are responsive to at least one of pressure and temperature. Further provided is a clamping device configured to reduce a cross-sectional diameter of a portion of the fluid conduit, in order to determine said parameter.

Abstract: A sensor in a building HVAC system includes a transducer configured to measure a variable in the building HVAC system and to generate a sensor reading indicating a value of the measured variable. The sensor includes a communications interface configured to provide the sensor reading to a control device in the building HVAC system and a near field communication (NFC) circuit separate from the communications interface. The NFC circuit is configured to facilitate bidirectional NFC data communications between the sensor and a mobile device. The sensor includes a processing circuit having a processor and memory. The processing circuit is configured to wirelessly transmit data stored in the memory of the sensor to the mobile device via the NFC circuit, wirelessly receive data from the mobile device via the NFC circuit, and store the data received from the mobile device in the memory of the sensor.

Abstract: A supplemental fuel system includes a supplemental fuel tank, an electronic valve, a voltage sensor, and a controller. The supplemental fuel tank is configured to store a supplemental fuel configured to supplement a primary fuel used by an engine. The electronic valve is configured to be positioned between the supplemental fuel tank and an air supply system for the engine. The voltage sensor is configured to acquire voltage data from a power supply indicative of a voltage of the power supply. The power supply is configured to receive power from an alternator driven by the engine. The controller is configured to control the electronic valve such that the electronic valve is closed in response to the voltage being less than a voltage threshold indicating that the engine is not operating and open/openable in response to the voltage being greater than the voltage threshold indicating that the engine is operating.

Abstract: A viscosity-sensing apparatus includes a ring and sensors. The ring is connected to a pipe of a tank. The sensors are connected to an internal face of the ring at various heights. Sludge travels into the ring from the tank through the pipe. The sensors sense values of viscosity of the sludge at various depths in the ring.

Abstract: A fluid flow device that can measure and control a flow of a fluid is described. Various procedures, including measuring, controlling, balancing, or calibration procedures can leverage differential pressure measurement. These differential pressure measurements can be measured across the fluid flow device such that a first pressure measurement is taken upstream of the fluid flow device while a second pressure measurement is taken downstream of the fluid flow device. Moreover, one or more of the various pressure measurements, and in particular the downstream pressure measurement, can be performed at stagnation zone where the flow has stagnated. Such can provide significant amplification and/or turndown capabilities.

Abstract: Systems and methods for generating pressure data from at least two pressure sensors, storing one or more parameters indicative of water cut in a neural network model, receiving pressure data from at least the two pressure sensors respectively indicative of the pressure at two points of a well bore, determining a pressure drop between the two points, generating an input water cut estimate, estimating a dynamic pressure loss to initiate an iterative process, estimating a potential energy loss, inverse modeling a water cut estimate, comparing the water cut estimate to the input water cut estimate to generate a water cut ?, utilizing the water cut estimate as the input water cut estimate for the iterative process when the water cut ? exceeds a threshold, and continuing the iterative process until the water cut ? is below the threshold.

Abstract: A monitoring device includes a sensor module disposed between an aeroshell and a cavity assembly. A surface of the aeroshell and a surface of the cavity assembly may form a flow-facing surface of the monitoring device. A junction area on the flow-facing surface within which the aeroshell abuts the cavity assembly may be a smooth surface to minimize the disruption to the surrounding flow of fluid. The sensor module may sample the absolute pressure from ports distributed about the flow-facing surface. The absolute pressure measurements may be used to compute the velocity of the fluid flow, including speed and/or direction. The monitoring device may be powered by inductively received energy or harvested energy. In one variant of the monitoring device, the monitoring device may be constructed from an electrically coupled mosaic of flexible thin-profile tiles, each of which may be responsible for one functional aspect of the monitoring device.

Abstract: A device for measuring flow rate of wet gas based on an exempt radioactive source, includes a section of cylindrical pipe and a conical throttle located inside the cylindrical pipe and coaxially arranged therewith. The conical throttle includes a head cone section and a tail cone section arranged to have a common bottom surface. The head cone section faces a wet gas inlet of the cylindrical pipe. An annular gap is defined between the inner wall of the cylindrical pipe and the maximum diameter of the conical throttle for passage of wet gas. An exempt radioactive source block is arranged at the maximum diameter of the conical throttle in such a way that the gamma rays emitted from the radioactive source block can transmit radially through the annular gap to reach the gamma ray detector located outside the cylindrical pipe.

Abstract: A computer-implemented system includes a downhole tool in a bottom hole assembly attached to a drill string, configured to perform gas measurements during drilling operations. The downhole tool includes a housing to house the downhole tool; sensors positioned along external walls of the housing and including coaxial resonators; electrical circuitry located inside the downhole tool and configured to enable communication by, and operation of, the downhole tool; at least one processor configured to convert scattering parameter 11 signals received from sensors to permittivity values and determine signatures from permittivity values. A memory stores data collected by sensors. A sensor system monitors changes from a baseline signal of drill mud produced during the drilling operations, the changes based at least in part on signatures determined from permittivity values. The downhole tool provides communications to surface systems when a gas kick event is detected by the downhole tool.

Abstract: The present invention provides a refrigerator comprising: a cabinet having a storage chamber; a door for opening or closing the storage chamber; a case in which an inlet through which air flows from the storage chamber and an outlet through which the air is discharged to the storage chamber are formed; an evaporator provided inside the case for exchanging heat with the air to supply cool air; and a differential pressure sensor provided inside the case.

Abstract: The invention provides an apparatus and method for measuring fluid flow rates. The apparatus comprises a meter body comprising a throughbore with a fluid flow path and a flow displacement member. The apparatus also provides a sleeve slidably mounted within the fluid flow path. The sleeve is configured to be movable between at least two axial positions within the fluid flow path to select a predetermined flow rate measurement range for the flow measurement apparatus.

Abstract: Embodiments of the present disclosure aim to provide advanced multiphase flow meters utilizing advanced sensor configurations and data analysis. In an embodiment, a system is provided and configured with permittivity sensors configured around the throat section of an extended throat venturi enclosure. In a particular embodiment, the permittivity sensors in the described system are configured with a computer system or a micro-computer system, that can be configured with a computer circuit board comprising a processor, memory, networking capability, and software.

Abstract: A method for continuously controlling fluid flow rates through a well (4) provides to shut off the drilling mud at the well inlet and outlet and detect measurements of flow rate and density of said drilling mud by a Venturi measuring device (10,2).

Abstract: An arrangement for controlling flow includes a flow control element, an actuator, a linkage assembly, and a sensor module. The linkage assembly is coupled between the flow control element and the actuator, and includes a rotatable linkage element coupled to impart force to the flow control element. The sensor module is affixed to the rotatable linkage element. The sensor module includes a MEMs-based strain gauge affixed to a substrate and operably coupled to measure torque on the linkage element, and a processing circuit disposed on the substrate. The processing circuit is operably coupled to receive torque measurement information representative of the measured torque. The processing circuit generates a fluid flow measurement value based on the torque measurement information and position information representative of a position of a flow control device of the flow control element. The flow control device is mechanically coupled to the rotatable linkage element.

Abstract: The invention relates to a device for online measurement of gas flowrate and liquid flowrate of a wet gas in a horizontal pipe, comprising the following parts: a horizontal Venturi tube, comprising a truncated cone-shaped inlet pipesection with section area reduced gradually, a cylindrical throat pipesection and a truncated cone-shaped outlet pipesection with section area increased gradually; and a gamma ray monitor, comprising a gamma ray emitter and a gamma ray detector arranged in a manner that gamma rays emitted by the gamma ray emitter can radially pass through the cross section of the throat pipesection to reach the gamma ray detector. The invention also relates to a method for online measurement of gas flowrate and liquid flowrate of a wet gas in a horizontal pipe by using above device.

Abstract: The present invention relates to a system for measuring electrical characteristics of a fluid flowing through a section of a pipe, the system comprising a coaxial resonator, formed by an essentially coaxial insert in said pipe defining an annular volume between a chosen part of said insert and the pipe wall, said insert and pipe wall being made from an electrically conductive material, the system further comprising at least one antenna adapted to emit electromagnetic signals into and receive electromagnetic signals from said coaxial resonator, and means to measure the frequency response of said coaxial resonator within a frequency range including the waveguide mode TE11 of said coaxial resonator, The coaxial insert is mounted to the pipe wall through at least one support leg being positioned outside said annular volume, and one electrically conductive fin is positioned at least partially in the annular volume, said fin being positioned in a radial plane, said plane being different from the plane of said at le

Abstract: Methods and systems for accurately measuring and monitoring accumulated volume of hydraulic fluid in a blowout preventer (BOP) system, specifically for a function of interest, are disclosed. One method includes initializing a state machine algorithm, the state machine algorithm responsive to a BOP function of interest being activated; measuring an initial hydraulic flow rate baseline and an initial pressure baseline to create a hydraulic impedance variable for use in the state machine algorithm; monitoring an aggregate hydraulic flow rate and pressure of the BOP system over time; applying the hydraulic impedance variable to negate BOP system hydraulic flows not related to the BOP function of interest; and applying the state machine algorithm to determine when the BOP function of interest has been completed responsive to a total accumulated volume of hydraulic fluid.

Abstract: A flow measuring device, comprising a container for receiving a flow of liquid, a plurality of optical sensors associated with the container, each of the plurality of optical sensors producing an output signal dependent upon the presence of liquid reaching a level in the container associated with each optical sensor, means for modifying the output signal in accordance with at least one predetermined temperature compensation factor, and means for calculating a flow rate from the time at which the liquid traverses between two levels in the container.

Abstract: A venturi flowmeter for connection to single-use containers is provided. The venturi flowmeter includes a meter body formed of a polymer and configured to allow fluid flow therethrough. A first annular diaphragm is mounted proximate an inner surface of the meter body has a first internal diameter. A second annular diaphragm is mounted proximate an inner surface of the meter body has a second internal diameter different from the first internal diameter.

Abstract: The present disclosure relates to systems and methods for determining a rheological parameter of a fluid within a wellbore. The methods comprise receiving a plurality of differential pressure measurements of a fluid within a flow region of the wellbore; storing the plurality of differential pressure measurements; generating a curve based on the plurality of differential pressure measurements; and determining the rheological parameter of the fluid using the curve. The systems comprise a conduit arranged in a wellbore; a plurality of pressure sensors along the conduit configured to measure pressure of the fluid within the wellbore; and a processing device. The processing device is configured to: receive a plurality of differential pressure measurements of the fluid from the pressure sensors; store the plurality of differential pressure measurements; generate a curve based on the plurality of differential pressure measurements; and determine the rheological parameter of the fluid using the curve.

Abstract: Aspects and embodiments disclosed herein indicate a correlation exists between a specific gravity of combustible fuel and the occurrence of low-speed pre-ignition (LSPI) within engines. Thus techniques are disclosed herein for online measurement of the specific gravity of fuel within an engine, and allow for preventative measures to be executed to minimize or otherwise mitigate the incidence of LSPI when the calculated specific gravity of the fuel exceeds a predefined threshold. In an embodiment, the preventative measures may include, for example, altering or otherwise adjusting an engine map such that an injection timing scheme injects less poor-quality fuel into engine cylinders, thus advantageously preventing the engine from operating at full-power when conditions for LSPI are present.

Abstract: A filtration apparatus whose interior is divided into a filtrate zone and a filtering zone. The filtering zone is adapted to receive a stream of raw-water and a lower portion of its volume is filled with filtering grains, and the filtrate zone is adapted to receive a filtrate obtained from passage of said stream of raw-water via the filtering grains and a perforated member. The apparatus further includes a pressure reducing device in fluid communication with the lower portion of the filtering zone and with an upper portion thereof. The pressure reducing device is adapted to receive a stream of water and responsively to continuously remove filtering grains from said filtering zone and separate filtration residues therefrom by the reduction of pressure conditions thereinside, and direct a stream comprising the stream of water and the separated filtering grains and filtration residues to the upper portion of said filtering zone.

Abstract: A device is disclosed for measuring total pressure of a fluid flow comprises a tubular member having an inlet chamber with an inlet opening at a first end of the tubular member. The tubular member also comprises an outlet chamber having an outlet opening at a second end of the tubular member. The inlet opening has a diameter transverse to the longitudinal axis and the outlet opening has a second diameter transverse to the longitudinal axis. The ratio of the first diameter to the second diameter is from 3:1 to 10:1. The tubular member also includes a transitional chamber between the inlet chamber and the outlet chamber. Total pressure can be measured in the inlet chamber.

Abstract: A plasma etching apparatus of the present disclosure etches a substrate by plasma of a processing gas. The plasma etching apparatus includes a processing container; a holding unit configured to hold a substrate; and an electrode plate. The plasma etching apparatus further includes configured to supply the processing gas to a space between the holding unit and the electrode plate and disposed in n (n is a natural number of two or more) regions of the substrate divided concentrically in a radial direction, respectively. In addition, the plasma etching apparatus further includes a high frequency power source configured to supply a high frequency power to at least one of the holding unit and the electrode plate so as to generate plasma. The plasma etching apparatus controls a flow rate of the processing gas.

Abstract: A method of determining a mass flow rate of product being applied with an agricultural implement includes the steps of: calibrating a pressure drop across a known distance in an air line at a number of air flow rates; metering a product at a desired application rate into the air line at a selected air flow rate; establishing a pressure drop across the known distance at the selected air flow rate, while the product is being metered; calculating a specific pressure drop by dividing the established pressure drop by the determined pressure drop; ascertaining the values of parameters A and B using the mathematical expression: ?=1+A?+B?{square root over (?)} ?where: ?=specific pressure drop; ?=mass loading ratio; and A and B=parameters based on measured data for the specific product being applied; and estimating a mass flow rate of the product being applied.

Abstract: An embodiment of the invention is one that, in the case where a sampling part is configured to include a plurality of venturis, with suppressing an increase in size of an apparatus and an increase in cost, accurately obtains a diluent gas flow rate in accordance with a diluted exhaust gas flow rate obtained on the basis of a combination among the plurality of venturis, in which the sampling part collecting part of diluted exhaust gas is configured to parallel connect the plurality of venturis that control the flow rate of the diluted exhaust gas, and a flow rate control part provided in a diluent gas sampling flow path is configured to parallel connect a plurality of venturis that control the flow rate of diluent gas to be introduced into a diluent gas analyzing device.

Abstract: A measuring transducer comprises at least one measuring tube for carrying a flowing medium as well as a transducer housing mechanically coupled with the at least one measuring tube. The transducer housing includes: an inner shell forming a cavity accommodating the at least one measuring tube; and an outer cladding formed at least partially by means of yarn, namely cladding placed outside of the cavity and surrounding the inner shell.

Abstract: An aspect provides a flow metering apparatus, comprising: a fluid conduit having a differential pressure producer therein; at least one pressure port angled between 0 and 90 degrees in a wall of the fluid conduit; and at least one other pressure port; wherein the at least one pressure port and the at least one other pressure port provide pressure signals. Other aspects are described and claimed.

Abstract: A pressure sensing element includes a sensing sub-element disposed on a diaphragm, the element including a shield disposed over the sub-element and configured to substantially eliminate influence of external charge on the sub-element during operation. A method of fabrication and a pressure sensor making use of the pressure sensing element are disclosed.

Abstract: A pressure sensing element includes a sensing sub-element disposed on a diaphragm, the element including a shield disposed over the sub-element and configured to substantially eliminate influence of external charge on the sub-element during operation. A method of fabrication and a pressure sensor making use of the pressure sensing element are disclosed.

Abstract: Provided are a steam flow metering device and a metering method therefor. The device mainly comprises a mono-energetic gamma sensor (5), a Venturi-type flowmeter (6), a temperature transmitter (2), a pressure transmitter (3), a pipe connection section at the steam-inlet (1), and a pipe connection section at the steam-outlet (7), the function thereof being to measure the quantity of saturated water and saturated steam within the steam effectively and in real time.

Abstract: Method for monitoring a body inserted in pipe conducting a fluid flow, the body being positioned in a distance from the pipe wall providing a gap between the body and the pipe wall, the gap constituting an electromagnetic, e.g. microwave, resonator, at least one coupling probe being positioned close to said gap, the method comprising the steps of applying an electromagnetic signal, monitoring the frequency response of the resonator through the probe, and analyzing the frequency response to provide a measure of movements, e.g. vibrations induced by a turbulent flow, of the body. The invention also relates to an insert with support structure especially shaped to avoid influence on the resonance measurement.

Abstract: A method for determining the flow rates of a fluid comprising a multi-component mixture of a gas and at least one liquid in a pipe, the method comprising the following steps: a. the permittivity of the multi-component mixture is determined based on an electromagnetic measurement, b. a statistical parameter related to the electromagnetic measurement is calculated, c. the density of the multi-component is determined, d. the temperature and pressure are obtained, e. based on the knowledge of densities and dielectric constants of the components of the fluid mixture, and the result from the above steps a-c, the water fraction of the multi-component mixture is calculated, characterized by a method for determining the liquid fraction and flow rates of the multi-component mixture where f. the liquid fraction is calculated based on the statistical parameter from step b and the calculated water fraction from step e using an empirical derived curve, g. the velocity of the multi-component mixture is derived, and h.

Abstract: Both a flow meter system and method are provided for accurately measuring the percentage amounts of liquid and gas phases in a multiphase flow through a conduit when the liquid phase constitutes a small minority portion (e.g., less than about 20%) of the multiphase flow. The system includes a flow meter that includes a differential pressure sensor connected across a Venturi in the conduit, and a dual energy fraction meter, each of which is operably connected to a digital processor. The system further includes a pump connected to the conduit upstream of the flow meter that introduces at least one pulse of a known quantity of liquid, the pulse being sufficient in volume to temporarily increase the liquid phase by a detectable amount.

Abstract: A disclosed method of operating an engine may include discharging exhaust gas from at least one combustion chamber of the engine. The method may also include recirculating at least a portion of the exhaust gas to the at least one combustion chamber through an EGR system, including directing at least a portion of the exhaust gas through an EGR duct. Additionally, the method may include sensing pressure in a portion of the EGR duct by directing the pressure to a first pressure sensor via a first sensor passage having a first end connected to a portion of the EGR duct and a second end connected to the first pressure sensor, while maintaining a temperature of gas in the first sensor passage adjacent the second end at a bulk temperature of at least about 75 percent of a bulk temperature of gas in the first sensor passage at the first end.

Abstract: An apparatus and method for monitoring sanitary sewer systems designed to carry away wastewater through a system of buried pipes, often referred to as “sewer lines”, to a sewage treatment facility, the apparatus and method use a weir which facilitates the collection of flow rate data in the sewer lines which in turn facilitates the determination of infiltration and inflow (“I/I”) of rain water, or clear water, into the sewer system in a manner which further allows the identification of specific I/I locations so that repair and construction of sewer systems can be efficiently coordinated.

Abstract: A flow pattern transition pipe for use in a pneumatic conveyance system is provided. The flow pattern transition pipe comprises a first expansion pipe section gradually increasing in inner diameter in an axial direction, a second shrink pipe section following the first section from a maximum inner diameter end of the first section and gradually reducing in inner diameter in an axial direction away from the first section, and a third pipe section following the second section from a minimum inner diameter end of the second section, with a substantially identical inner diameter smaller than a minimum inner diameter of the first section. An axial length of the first section is from about three to about five times of the axial length of the second section.

Abstract: Infusion systems and methods containing unique inner passage configurations are provided to improve the in-line detection of air in a fluid delivery line of an infusion system by reducing the problems associated with the presence of bouncing air bubbles and stuck fluid droplets in the fluid delivery line.

Abstract: A valve includes a housing, a stern supported by the housing, and a valve member coupled to the stem. The valve member has a first passage defined therein with a metering flow profile, An apparatus includes a well tree having a production bore and a flow metering valve coupled to the well tree and communicating with the production bore. The flow metering valve Includes a valve member having a first passage defined therein with a metering flow profile and a second passage defined therein with an unrestricted flow profile. The second passage having a diameter substantially equal to a diameter of the production bore.

Abstract: A system for measuring and monitoring the internal liquid within a three phase separator allows a user to accurately and reliably calculate the volumetric flow rate of the liquids exiting the three phase separator. For each liquid inside of the three phase separator, a differential pressure device is attached to where the extension fitting enters its respective liquid. Once a dump valve is actuated, the extension fitting guides its respective liquid out of the three phase separator, and the differential pressure device creates a differential pressure within the respective liquid. A sensor reads the differential pressure through a pair of sensing lines. The sensor relays the differential pressure reading to an RTU flow computer that calculates the volumetric flow rate of the liquid exiting the three phase separator. The calculation is then sent to a SCADA system, which allows the user to observe the volumetric flow rate in real time.

Abstract: This invention sets forth a water flow restrictor for insertion into a water line connected to a water dispensing fixture. The restrictor includes an in-line restrictor body having a longitudinal flow passageway. The body also has an upstream coupling and a downstream coupling so that the body can be coupled into a water line. The body further has an upstream water receiving chamber and a downstream water passing chamber. An orifice of selectable restrictive size is located between the chambers. The orifice limits the flow of water through the passageway. The upstream water receiving chamber has an elliptically converging interior configuration approaching the orifice.

Abstract: A flow meter that may be used in an exhaust gas recirculation (EGR) system is disclosed. The EGR system may be part of an internal combustion engine or other power source. The flow meter includes a venturi that includes a body that defines an inlet section, a throat and a diverging outlet section. The flow meter also includes a sensor coupled to the venturi via a plurality of pressure passages.

Abstract: A fluid nozzle for a pipe having a flow meter includes an inner surface having a contour. The contour is substantially defined by a compound of two ellipsoidal bodies of revolution which prevents negative pressure gradients in the fluid along the inner surface as fluid in the pipe flows through the nozzle in the pipe. The nozzle includes a throat, wherein a ratio of a diameter of the throat to a diameter of the pipe upstream of the throat is 0.7 or less.

Abstract: A remote seal assembly for subsea applications is provided. The assembly includes an upper housing having a fluid coupling for coupling the remote seal to a process fluid pressure measurement device. A lower housing is coupled to the upper housing and has an interface that is configured to mount to a pressure vessel. The lower housing also has a process fluid inlet. An isolation diaphragm is disposed between the upper and lower housings. At least one of the upper housing, lower housing and isolation diaphragm are constructed from a material suitable for immersion in saltwater. In some embodiments, the lower housing has a shoulder disposed about the process fluid inlet and a plurality of self-energizing seals configured to couple the assembly to a venturi flow meter body. A subsea process fluid flow measurement system is also provided that includes a pressure transmitter and at least one subsea remote seal assembly.

Abstract: An eccentric, smoothly tapered body for installation into cylindrical pipe to cause a constriction in the pipe to facilitate measuring the flow of fluid through the pipe. The body defines a flow constrictor having a smoothly tapered inner surface having a leading edge and a trailing edge and an apex therebetween. A bore extends through the flow constrictor at the apex. Pressure is measured at the bore at the apex and upstream of the flow constrictor and flow rate is calculated from the pressure differential therebetween.

Abstract: A method and system is provided for measuring a flow rate of a gas/liquid flow. The method and system for measuring the flow rate include flowing a swirling gas/liquid flow separated into a gas core and a liquid outer layer through a conduit containing a constriction having a reduced conduit cross-section, measuring the differential gas core static pressure between a position upstream of the constriction and a position at the constriction, measuring a further quantity which provides the flow rate of the gas, the flow rate of the liquid, or a correlation between the flow rate of the gas and the flow rate of the liquid, and determining the flow rates of the gas and the liquid from the differential gas core static pressure and said measured further quantity.

Abstract: A flowmeter device for measuring a flow rate of a fluid includes a conduit for the fluid flow. The conduit is characterized by a cross-sectional area and includes at least one section within which the cross-sectional area is different from the cross-sectional area of at least one other section of the conduit. The device also includes a reference tube separated from the conduit by a wall and at least one opening in the wall between the section and the reference tube. The device includes a flexible diaphragm forming a space between the diaphragm and a region of the wall at the section of the conduit, and which includes the opening, to inhibit flow of the fluid between the conduit and the reference tube.

Abstract: A simple, passive and rugged device for measuring the flow rate of liquid. A variable area obstruction valve, a differential pressure sensor and a densitometer are combined in a single housing to provide for a highly accurate and precise measure of mass flow.

Abstract: A variable throat Venturi flow meter includes an upstream pipe section having an upstream cross-sectional area, a throat section having a variable throat cross-sectional area that is smaller than the upstream cross-sectional area, and a plurality of section-varying elements adapted to temporarily vary the throat cross-sectional area to allow a downhole tool to pass through the throat section.