Turbulence Measurements With A New Two Components Ultrasonic Profiler

摘要

In the present paper, a data set of time-resolved two components velocity profile measurements under steady uniform turbulent rough clear water and sheet-flow are presented. The purpose of this campaign was to evaluate the performances of a commercial ADVP, the UB-Lab 2C from the company Ubertone, by comparing it to a well-established instrument, the ACVP, developed by the LEGI. This measurement method provides quasi-instantaneous co-located two (2C) components velocity profiles, overcoming limitations of previously developed acoustic measurement methods, and allowing to resolve fine flow scale for the characterisation of turbulence statistics and turbulent processes. Taking into account flow condition differences in the tilting flume with sediment pit, the results of this measurement campaign demonstrates the good performance of the commercial ADVP compared to the ACVP, in clear water and sheet-flow. Its capabilities for time-resolved turbulence measurements are also supported by similar results described in the literature, namely, the significant reduction of Von Karman parameter in sediment-laden flows and the higher contributions of ejections in CW (and sweeps in SF) for the Reynolds shear stress. This suggests the potential of this acoustic system to analyse a wide range of hydrodynamic phenomena, both in rigid-bed and mobile-bed, in which turbulence plays a major role.