SIGNAL POST-PROCESSING TECHNIQUE AND UNCERTAINTY ANALYSIS OF ADV'S TURBULENCE MEASUREMENTS ON HYDRAULIC JUMPS

ROMAGNOLI, M.; GARCIA, C. M.; LOPARDO, R. A.

JOURNAL OF HYDRAULIC ENGINEERING

ASCE-AMER SOC CIVIL ENGINEERS

Año: 2011

0733-9429

This note presents experimental results on an error analysis of ADV turbulence measurements in free hydraulic jumps incorporating recent ADV signal processing technique. This works aims to quantify the influence of each error source in acoustic Doppler measurements (i.e. presence of spikes, Doppler noise and filtering effects due to the ADVs sampling strategy) on the variance and integral time scale computations as well as defining the corresponding confidence interval for each reported value. Experiments were conducted for an upstream Froude number of 3.0. The relative error contribution of each source to both raw longitudinal variance (RECV) and raw longitudinal integral time scale (RECT) decreases downstream. Inside the zone where aeration effects and high turbulence levels are relevant, Doppler noise constitutes the most important error source. Further downstream, where aeration effects and turbulence levels diminish, the error produced by the presence of spikes can be neglected while effects of both Doppler noise and ADVs sampling strategy are balanced. The relative confidence interval for corrected longitudinal variance ranges between 30% and 10% while relative uncertainty level for corrected longitudinal integral time scale varies from 80% to 50%. The results of this study point out the requirement for adequate signal post-processing technique and uncertainty analysis of ADV turbulence measurements.