Flow Measurement using Ultrasonic Cross Correlation

Flow Measurement using Ultrasonic Cross Correlation

Cross Correlation Method

  • The measurement method for universal use in slight to heavily polluted media
  • Very high measurement accuracy
  • Measures the real flow velocity profile

 

Average flow velocity and flow cross section are required to determine the flow Q. This leads to the general formula:

Q = v (average) • A

The flow cross section A is determined by continuously measuring the filling level taking the channel shape as well as the channel dimensions into account. Most media contain a certain load of dirt particles or gas bubbles which move in the same velocity as the medium itself.

 

Your Benefits

  • Highest measurement accuracy
  • Stable and reliable readings
  • No calibration required
  • Extremely high measurement dynamics from lowest flow rates up to full filling

Flow Velocity Measurement (v) using Cross Correlation

The flow velocity determination method is based on the ultrasonic reflection principle.
One of the most modern and most efficient flow velocity measurement methods is the NIVUS correlation method. The reflecting particles contained within the medium (debris, min­erals or gas bubbles) are scanned using an ultrasonic impulse transmitted in a defined angle. The resulting echo is then saved as image or echo pattern.

The echo pattern of a second scan a few milliseconds later is saved as well.

The positions of the reflecting particles is determined by correlating/comparing both saved signals. The particles can be found in different positions in both images since they move with the medium. Considering the beam angle it is possible to directly convert the temporal shift of the particles into their velocity which is equal to the flow velocity of the medium.
This allows gaining high accurate measurement values without calibration measures.

Our measurment systems utilise up to 9 x 16 gates for flow measurement. The measured flow profile can be indicated directly on the display.

Functional Principle Cross Correlation

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