Velocity and turbulence measurements by ultrasound pulse Doppler velocimetry

This paper describes a velocimeter, based on back-scattering of ultrasonic waves by particles, designed for velocity measurement of suspended sediments within the flow of sewer systems. The ultrasound pulse Doppler velocimeter (UPDV) needs no calibration and is therefore a potentially useful tool for measuring velocities in laboratory experiments or in sewer systems. The potential of the developed system to determine the velocity in turbulent pipe flow was investigated. Two different approaches were used to estimate velocity: the well-known temporal method, i.e., the pulse–pair technique and the spectral identification based method, developed by our research group. Measurements have demonstrated the ability of the apparatus, on the one hand, to measure unsteady turbulent velocities, and on the other hand, to investigate experimentally the statistical properties of homogeneous and isotropic turbulence. A good agreement between experimental results and theory was observed. The validation of these laboratory measurements permits to extrapolate them to sewer systems.