Calibration and Verification of Operation Parameters for an Array of Vectrino Profilers Configured for Turbulent Flow Field Measurement around Bridge Piers—Part I

Abstract

Flow mapping around bridge piers is crucial in estimating scour development potential under different flow conditions. The reliable measurement of turbulence and the estimation of Reynolds stress can be achieved on scaled models under controlled laboratory experiments using high-frequency Acoustic Doppler Velocimeter Profilers (ADVP) for flow measurement. The aim of this paper was to obtain operation parameters for an array of Vectrino Profilers for turbulent flow field measurement to reliably measure the flow field around bridge piers. Laboratory experiments were conducted on a scaled river model set up in an open channel hydraulic flume. Flow field data were measured on three characteristic profiles, each containing five measurement points collected by ADVPs configured as an array of two instruments. The determination of the operation parameters was done as a two-step process—calibration through the flume’s pump flow rate and verification with Acoustic Doppler Current Profiler RioGrande field data. Based on the results, the following setup for ADVPs’ operation parameters can be used to obtain reliable flow data in the scour hole next to the bridge pier: adaptive Ping Algorithm, Transmit Pulse Size of 4 mm and Cell Size of 1 mm.

Calibration and Verification of Operation Parameters for an Array of Vectrino Profilers Configured for Turbulent Flow Field Measurement around Bridge Piers—Part II

“…In the setup used for this paper, flow is disrupted by complex hydraulic structure (model pier and riprap), standard logarithmic velocity profile characteristic for the unobstructed flow is not expected, and velocity profiles are "random" which limits the applicability of visual evaluation of the velocity profile for XS-DS. However, the difference between Adaptive and Max interval PA is not significant, as demonstrated by Liu et al (Table 3 from [54]), and as also stated in Part I of this research where differences between configurations C2 and TC are small for all metrics (see Table 3 from [29]). Liu et al [54] also pointed out that CS and TPS should be treated with caution, which agrees well with the results of this study as discussed earlier, showing that TPS has the largest effect on the results, while CS has a larger effect than PA but not as large as TPS (Figures 5-8).…”

“…A sensitivity analysis is performed to determine the influence of different parameters on the measured velocity data. During the calibration and verification procedure [29], configuration C6 (PA set to Adaptive, CS set to 1 mm, and TPS set to 4 mm) proved to be the best suited for flow field measurements in the model of bridge pier protected with riprap that was described in detail in Part I of this research. For that reason, configuration C6 will be referred to as the Target Configuration (TC).…”

“…Configurable velocity profiling parameters were Ping Algorithm (PA), Transmit Pulse Size (TPS), and Cell Size (CS). The optimal configuration against which all others were evaluated was configuration C6, defined as the most accurate for flow measurement around the bridge pier in Part I paper of this research [29], where calibration and verification of ADVPs' operation parameters were presented. Results of calibration and verification have shown that the calculated flow rates in the flume correspond best with the pump flow and field ADCP data when ADVP is configured according to the C6 configuration with the following parameters: Ping Algorithm set to Adaptive, Transmit Pulse Size equal to 4 mm, and Cell Size of 1 mm.…”