Calibration of Horizontal Acoustic Doppler Current profilers by three dimensional CFD simulations

Abstract

This study presents a calibration method of horizontal acoustic Doppler current profilers (H-ADCP), based on 3D Computational Fluid Dynamics (CFD) simulations. Rigidly mounted H-ACCPs are currently used to continuously monitor water discharges. In this study three instruments were employed at separate sites in an unlined rock-blasted hydro power tunnel. The total discharge in the tunnel was predicted by fitting numerical and measured velocity profiles. The accuracy of the method was evaluated by comparing discharge predictions to results obtained by thermodynamic efficiency measurements. This study shows that 3D CFD simulations not only can be used to accurately calibrate H-ADCP, but also to assess the flow conditions at the locations of installation. An average error of 2% was obtained for the tunnel stretch that possessed the most uniform flow. However, the precision of the discharge estimates were confined by the CFD code's capability to correctly resolve the flow pattern.