Fluid Surface Velocity Measurement Using Millimeter-Wave Radar Sensor

Abstract: Contactless fluid surface velocity measurements with radar technology presents novel ways of determining fluid flow. The Acconeer A121 sensor is used, which is a pulsed coherent 60 GHz millimeter-wave radar, with high accuracy and low energy consumption. Fluid flow data is obtained from three different sites; in the Acconeer lab, a lab in the UK, and in three sewage pipes of VA SYD. Initially, data from the Acconeer lab is analysed and used to implement the algorithm which later is run and tested on the other data. The basics of the algorithm is creating periodograms by FFT in fast-time and averaging in slow-time dimension. The frequency components are converted to velocities by knowledge of the wave specifics. The results show that forward and backward flow is easy to measure and distinguish. From Acconeer and UK lab the velocity spectra cohere with the reference velocity data. For the VA SYD sites, the 1500~mm pipe show some peak close to Nivus reference, but the signal strength is weak due to small surface ripples. For the pipe of 750~mm the spectra cohere well with Nivus. The non-stationary flow of the 800~mm pipe seem to cause some error in the measurement.