In an embodiment a method includes transmitting a signal train through a medium, wherein the signal train includes a sequence of waves of a first group and of a second group, the first and second groups being shifted in a time domain according to a predetermined phase shift, receiving the signal train as a received signal train and as a function of time, detecting a phase shift in the received signal train, assigning wave periods of the received signal train to respective wave periods of the first group using the detected phase shift as reference and determining a sequence of time-of-flight signals from the sequence of waves of the first group and the assigned wave periods of the received signal train, respectively.

An ultrasonic air data system can include a pole having a length longer than a boundary layer thickness of a boundary layer flow such that at least a distal end of the pole is configured to extend outwardly from an aircraft surface to be at least partially outside of the boundary layer flow. The system can include a transmitter disposed on or in the pole at or near the distal end of the pole such that the transmitter is located at least partially outside of the boundary layer flow when in use, wherein the transmitter is configured to output a transmitter signal. The system can include one or more receivers disposed downstream of the pole as defined by the boundary layer flow and configured to receive the transmitter signal.

A transducer system. The system comprises a transducer and circuitry for applying an excitation waveform to excite the transducer during an excitation period. The circuitry for applying has: (i) circuitry for applying a first waveform at a first frequency; and (ii) circuitry for applying a second waveform at a second frequency differing from the first frequency.

An acoustic air data sensing system includes an acoustic transmitter, a plurality of acoustic receivers, and a skin friction sensor. The acoustic transmitter is located to transmit an acoustic signal into airflow about an exterior of a vehicle. Each of the acoustic receivers is located at a respective angle from a wind angle reference line and a respective distance from the acoustic transmitter. The skin fiction sensor is positioned in a boundary layer region of the airflow that interacts with the acoustic receivers and transmitter. Based on time of flight values of the acoustic signal from the transmitter to each of the receivers and a skin friction measurement from the skin friction sensor as inputs to a transformation matrix, the acoustic air data sensing system outputs, from the transformation matrix, the true airspeed, the relative wind angle, and the speed of sound for operational control of the vehicle.

Provided herein are improved methods for estimating the flow velocity of a fluid in a vessel. Systems and methods are provided herein related to making and/or refining velocity measurements for flowing fluids, both single and multi-phase fluids, in vessels, such as pipes or conduits, utilizing contrast media property agent variations. In one aspect, this disclosure provides a method of determining a flow velocity of a fluid flow in a vessel including: providing a fluid flow having contrast media, the contrast media having a contrast media property variation; providing a detectable signal corresponding to the contrast media property variation; collecting the detectable signal at an upstream receiver to produce a first received signal; collecting the detectable signal at a downstream receiver to produce a second received signal, the downstream receiver being located downstream of the upstream receiver at a distance (L); filtering the first received signal and the second received signal through a contrast media variant filter to produce a first filtered signal and a second filtered signal; cross-correlating the first filtered signal and the second filtered signal to determine a time shift (t) between the first filtered signal and the second filtered signal; and estimating the velocity of the fluid flow using this relationship vflow=L/t.

A system and method for an aircraft includes an air data system and an acoustic sensing system. The air data system includes a pitot tube positioned to sense a pitot pressure of an airflow about an exterior of the aircraft, and an angle of attack vane positioned to sense an angle of attack of the aircraft. The pitot pressure and the angle of attack are used to determine first air data parameters. The acoustic sensing system is configured to emit acoustic signals about the exterior of the aircraft and sense the acoustic signals as sensed data. The sensed data is used to determine second air data parameters.

An acoustic air data sensing system includes an acoustic transmitter and a plurality of acoustic receivers. The acoustic transmitter is located to transmit an acoustic signal into airflow about an exterior of a vehicle. Each of the acoustic receivers is located at a respective angle from a wind angle reference line and a respective distance from the acoustic transmitter. Planar components of a velocity of the airflow are determined based on signal velocities of the acoustic signal to each of the plurality of acoustic receivers and the respective angles of the acoustic receivers from the wind angle reference line. Based on the planar components, the acoustic transmitter determines one or more of true airspeed and relative wind angle of the airflow about the exterior of the vehicle. The acoustic transmitter outputs the one or more of the true airspeed and the relative wind angle for operational control of the vehicle.

An acoustic airspeed sensor system can include at least one acoustic transmitter configured to provide an acoustic pulse, a plurality of acoustic receivers including at least a first acoustic receiver positioned at a first radial distance from the at least one acoustic transmitter and a second acoustic receiver positioned at a second radial distance from the at least one acoustic transmitter. The first acoustic receiver is configured to receive the acoustic pulse at a first time and output a first receiver signal. The second acoustic receiver is configured to receive the acoustic pulse at a second time and output a second receiver signal. The sensor system can include an air data module operatively connected to the first acoustic receiver and the second acoustic receiver. The air data module is configured to determine true air speed (TAS) based upon a first signal delay, a second signal delay, and a wind angle.

A measuring device determines a fluid variable with a control device, a measuring tube and a first vibration transducer arranged at the measuring tube. The first vibration transducer contains a vibration element. The vibration element has a vibration body, a first electrode on the measuring tube side and a second electrode averted from the measuring tube. The first electrode extends over a first end face of the vibration body. The second electrode extends to a second end face that lies opposite the first end face. A respective conductive contact element contacts the first electrode at a first end face and the second electrode at a second end face electrically and mechanically such that the vibration element is supported by the contact elements. A voltage between the first and second electrodes can be varied through the vibration element to excite a guided wave in a side wall of the measuring tube.

A measuring device determines a fluid variable via a control device. A measuring tube serves to guide the fluid, and a first vibration transducer is arranged at the measuring tube. The first vibration transducer has a supporting device and two vibration elements spaced apart from one another. A spring element is clamped between a side face of the vibration elements averted from the measuring tube, which presses the respective vibration element against the measuring tube. The control device drives the vibration elements such that they excite a guided wave in a side wall of the measuring tube guided directly in the side wall or indirectly via the fluid to a second vibration transducer arranged at the measuring tube or back to the first vibration transducer, to be detected there by the control device resulting in measurement data. The control device determines the fluid variable depending on the measurement data.