This paper reports the simultaneous generation of multiple fundamental ultrasonic guided wave modes L(0,1), T(0,1), and F(1,1) on a thin wire-like waveguide (SS-308L) and its interactions with liquid loading in different attenuation dispersion regimes. An application towards liquid level measurements using these dispersion effects was also demonstrated. The finite element method (FEM) was used to understand the mode behavior and their dispersion effects at different operating frequencies and subsequently validated with experiments. In addition, the ideal configuration for the simultaneous generation of at least two modes (L(0,1), T(0,1), or F(1,1)) is reported. These modes were transmitted/received simultaneously on the waveguide by an ultrasonic shear wave transducer aligned at 0°/45°/90° to the waveguide axis. Level measurement experiments were performed in deionized water and the flexural mode F(1,1) was observed to have distinct dispersion effects at various frequency ranges (i.e., >250 kHz, >500 kHz, and >1000 kHz). The shift in time of flight (TOF) and the central frequency of F(1,1) was continuously measured/monitored and their attenuation dispersion effects were correlated to the liquid level measurements at these three operating regimes. The behavior of ultrasonic guided wave mode F(1,1) when embedded with fluid at three distinct frequency ranges (i.e., >250 kHz, >500 kHz, and >1000 kHz) were studied and the use of low frequency Regime-I (250 kHz) for high range of liquid level measurements and the Regime-II (500 kHz) for low range of liquid level measurements using the F(1,1) mode with high sensitivity is reported.

Experimental Study on Dispersion Effects of F (1,1) Wave Mode on Thin Waveguide When Embedded with Fluid.

A system and method is disclosed for calibrating the volume of storage containers using ultrasonic inspection techniques. The exemplary ultrasonic calibration system comprises a plurality of acoustic devices controllably deployed in respective positions on the outside surface of the container. The acoustic devices include a transducer for sending acoustic signals across the internal volume of the container and sensors configured to detect the acoustic signals. The acoustic devices are in communication with a diagnostic computing device that controls the positioning and the operation of the acoustic devices and is further configured to determine the time time-of-flight of acoustic signals that travel between the various acoustic devices. Moreover, according to the specific arrangement of acoustic devices and the measured acoustic signal information, the control computer is configured to calculate the dimensions of the container and its internal volume.

System and method for acoustic container volume calibration

An Apparatus (1) for measuring the flow velocity (Vmed) of a fluid (5) in a pipe (2), comprises a housing (3) in which a first ultrasonic transducer (TD1) and a second ultrasonic transducer (TD2) are arranged at a predefined distance (L) to each other, wherein said first ultrasonic transducer (TD1) includes a first sound transmitting element (4a) and a transmitter/receiver unit (6a) mounted thereto which are adapted to emit first ultrasonic pulses (P1) at different angles and said second ultrasonic transducer (TD2) is adapted to receive said first ultrasonic pulses (P1) and generate a first electronic output signal, and wherein the second ultrasonic transducer (TD2) includes a second sound transmitting element (4b) and a transmitter/receiver unit (6b) mounted thereto which are adapted to emit second ultrasonic pulses (P2) at different angles, and wherein said first ultrasonic transducer (TD1) is adapted to receive said second ultrasonic pulses (P2) and generate a second electronic output signal, a control and evaluation unit (8) electrically coupled to said first and second transducers (TD1, TD2). The control and evaluation unit (8) is adapted to tune the first transducer (TD1) to generate a first electronic output signal of a maximum amplitude, and tune the second transducer (TD2) to generate a second electronic output signal of a maximum amplitude, and is adapted to measure the flight time (T1) of the first ultrasonic pulses (P1) and the time of flight (T2) of the second ultrasonic pulses (P2) travelling between the first and second transducer (TD1, TD2). The invention is further related to a method for measuring different parameters of a medium and the pipe by means of the apparatus (1).

Apparatus and method for measuring the flow velocity of a fluid in a pipe

A method and apparatus for positioning a mobile robot inside a vertical cylindrical Aboveground Storage Tank filled with a liquid is described. No additional hardware is needed other than the robot itself. The only piece of information needed is the tank's diameter which is known by construction. The robot carries proprioceptive sensors needed to propagate its position estimate as well as exteroceptive sensors needed to control the dead reckoning positional drift. Proprioceptive and exteroceptive data are merged using data fusion algorithms adapted to the sensor suite integrated in the vehicle, which can take different forms.

Method and apparatus for self-contained positioning of a mobile robot inside a tank

The present method makes use of a second receiver-transmitter pair, which, together with a first pair, forms a quadrilateral figure, the horizontal sides of which are parallel to the level of a liquid. In addition, the values of the energy characteristics of Lamb waves propagated simultaneously both between each of the horizontal receiver-transmitter pairs and between a second vertical receiver-transmitter pair are calculated using values obtained from certain horizontal pairs to determine the initial and final values of the measuring scale of other pairs, by means of which the height of the liquid level is determined and/or measured. The device comprises an acoustic receiver and an emitter, each provided with a piezoelectric transducer, which are mounted at a set distance from one another such that a liquid level monitoring region lies therebetween for the simultaneous excitation of a symmetrical and an antisymmetric normal zero mode Lame wave, the device further comprising a second acoustic receiver-transmitter pair and a signal generating and converting unit. Technical result: increased monitoring accuracy together with increased monitoring speed and a broader scope of application.

Method for controlling the liquid level in tanks as per characteristics of lamb waves and device for ultrasonic control of the liquid level in tanks

A system and a method for non-intrusive and continuous level measurement of a liquid enclosed by a solid wall of a vessel. The system comprises an ultrasonic transmitter for generating an ultrasound wave and for emitting it into the vessel wall, an ultrasonic receiver for receiving the ultrasound wave, and an electronic control and data processing unit (ECDU) for controlling operation of the transmitter and of the receiver and for determining the liquid level. The transmitter is able to emit the ultrasound wave as a primary Lamb wave into the vessel wall so that a part of the primary Lamb wave leaks from the vessel wall into the liquid in form of a pressure wave. The ECDU is adapted to repeatedly determine the time of flight of the pressure wave, change the ultrasonic frequency of the transmitter until the determined time of flight reaches a minimum, and determine the liquid level.

System and method for non-intrusive and continuous level measurement of a liquid

A system and a method for measuring a signal propagation speed in a liquid contained in a vessel or in a gaseous medium contained in the same vessel above the surface of the liquid are proposed. A transmitter transmits a first signal in a first direction which is at an acute or right angle to a first reflective surface, wherein the first reflective surface reflects the first signal so that it travels in a second direction is received by a first acoustic or electromagnetic receiver. The transmitter transmits a second signal in a predetermined third direction which is at an acute angle to the first direction, where the first or a second reflective surface reflects the second signal so that it travels in a predetermined and angular fourth direction with respect to the first or second reflective surface and is received by the first or a second acoustic or electromagnetic receiver. The speed of sound is then determined under the assumption that both the first and the second signals travel at the same average speed.

System and method for measuring a signal propagation speed in a liquid or gaseous medium

A system and a method for non-intrusive and continuous level measurement of a liquid are described, where the liquid is enclosed by a solid wall of a vessel (41). The system comprises an ultrasonic transmitter (48) for generating an ultrasound wave and for emitting it into the vessel wall, an ultrasonic receiver (49) for receiving the ultrasound wave through the vessel wall, and at least one electronic control and data processing unit (6) for controlling operation of the transmitter (48) and of the receiver (49) and for determining the liquid level (H) from a time of flight of the ultrasound wave. The transmitter (48) is a frequency-tunable transmitter which is placed at a first position at the outside of the vessel wall and below the level of the liquid surface (44) in such a way that the transmitter (48) is able to emit the ultrasound wave as a primary Lamb wave into the vessel wall so that a part of the primary Lamb wave leaks from the vessel wall into the liquid in form of a pressure wave (43) in an inclined and upward direction towards the liquid surface (44). The receiver (49) is placed at a second position at the outside of the vessel wall and below the level of the liquid surface (44) in such a way that the receiver (49) is able to receive a secondary Lamb wave which is generated by the pressure wave (43, 45) hitting the vessel wall after having been reflected by the liquid surface (44). The at least one electronic control and data processing unit (6) is adapted to repeatedly determine the time of flight (t) of the pressure wave (43, 45), change the ultrasonic frequency (f) of the transmitter (48) until the determined time of flight reaches a minimum (tmin), and determine the liquid level (H) based on the relationship that the minimum time of flight (tmin) equals the length of the travel path of the pressure wave (43, 45) divided by the speed of the pressure wave in the liquid (cL).

System and method for non-intrusive and continuous level measurement of a liquid specification

A simple, passive, single-element ultrasonic transducer is proposed for non-invasive measurements. Operating the transducer at different resonant modes allows the adaptation of the emitted sound pattern to various requirements. The emitted sound field is simulated and experimentally characterized. We demonstrate the suitability of the transducer prototype for non-invasive continuous level measurement in laboratory as well as field environment over an extended level- and temperature range. The measured performance fulfils typical requirements for invasive level sensors. The versatility of the transducer enables its application in a wide range of non-invasive measurements.

Frank Kassubek

Papers

System and method for non-intrusive and continuous level measurement of a liquid

System and method for measuring a signal propagation speed in a liquid or gaseous medium

System and method for non-intrusive and continuous level measurement of a liquid specification

Single-Element Ultrasonic Transducer for Non-Invasive Measurements