High-velocity air-water flows downstream of sluice gates including selection of optimum phase-detection probe

Felder, Stefan; Hohermuth, Benjamin; Boes, Robert M.

doi:10.1016/j.ijmultiphaseflow.2019.04.015

Cited by 32 publications

(26 citation statements)

References 53 publications

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“…Close to the channel bed and close to the free-surface y/Y 90 > 1.2, F tended to zero. In general, F increased with increasing flow rate, which is in agreement with previous studies of high-velocity air-water flows (e.g., Chanson & Toombes, 2002;Felder et al, 2019;Zhang & Chanson, 2017).…”

Section: Water Resources Researchsupporting

confidence: 92%

“…Both electrodes were insulated by epoxide, resulting in a sudden drop in resistivity if the needle tip was in air, corresponding to a raw voltage of about 0.5 V and to a voltage of about 4.3 V when the probe tip was in water. The WRL double-tip conductivity probes have been previously successfully benchmarked against other phase-detection probes in high-velocity air-water flows (Felder et al, 2019;Felder & Pfister, 2017), and further details on the working principles can be found in Cartellier (1990), Chanson (2002a), andPfister (2017). The conductivity probes were carefully placed in flow direction perpendicularly to the chute to optimize the piercing of the air-water interfaces with the needle tips.…”

Section: Water Resources Researchmentioning

confidence: 99%

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Flow Resistance and Energy Dissipation in Supercritical Air‐Water Flows Down Vegetated Chutes

Scheres

Schüttrumpf

Felder

2020

Water Resources Research

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Vegetation covers on dikes and embankment dams have proven as sustainable and cost‐effective surface protection against external erosion caused by hydraulic, mechanical, or climatic impacts. Determination of the hydraulic loads that act upon these covers requires the knowledge of the flow resistance. While the high‐velocity flows on vegetated slopes are often aerated, the flow aeration has rarely been considered, and no direct measurements of the air‐water flow properties have been conducted to date. The air‐water flow properties are needed for a direct estimation of important design parameters such as friction factors and residual head at the downstream end. Herein, unique air‐water flow measurements were conducted in high‐velocity air‐water flows down a vegetated chute with a 1:3 slope. Several vegetation covers were tested for a range of flow rates. The experiments revealed strong flow aeration within three‐dimensional, fragmented flows associated with complex interactions of vegetation and high‐velocity flows. The air‐water flow properties were measured with phase‐detection intrusive probes providing novel insights into aerated flows on vegetated chutes including distributions of void fraction, bubble count rate, and interfacial velocity as well as direct estimates of energy dissipation and flow resistance. The results highlighted strong flow aeration and energy dissipation for all vegetated configurations. The median equivalent Darcy‐Weisbach friction factors for all vegetations were within 0.19 to 0.45, comparable to aerated flows on stepped spillways. The present results highlighted the significant flow resistance of vegetated covers and the need to consider air‐water flow properties in the design of vegetated chutes.

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Section: Water Resources Researchsupporting

confidence: 92%

Section: Water Resources Researchmentioning

confidence: 99%

Flow Resistance and Energy Dissipation in Supercritical Air‐Water Flows Down Vegetated Chutes

Scheres

Schüttrumpf

Felder

2020

Water Resources Research

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“…Cummings and Chanson, 1997) and fiber optical probes (e.g. Boes, 2000), as shown in Felder and Pfister (2017);Felder et al (2019). The measurement uncertainty of the conductivity probes in this manuscript is therefore expected to be similar to the data presented in table 1.…”

Section: A Glimpse On Measurement Accuracysupporting

confidence: 66%

“…A convergence analysis of the stepped spillway data showed that sampling durations T > 45 s could further improve the measurement accuracy (Appendix A). The raw voltage signals were recorded with the same LabVIEW-based data acquisition system using a high-speed acquisition unit (National Instruments USB-6366) and further details on the overall probe designs can be found in Felder and Pfister (2017) and Felder et al (2019). Table 3: Experimental flow condition and dual-tip phase-detection probe specifications for the re-analysed datasets; CP: phase-detection conductivity probe; FO: phase-detection fiber optical probe; Reynolds number Re = q/ν, with ν the kinematic viscosity of water and q the specific discharge; f : sampling rate, T : sampling duration; ∆ x: streamwise tip separation distance.…”

Section: General Remarksmentioning

confidence: 99%

“…Experimentally recorded signals are different from synthetic signals and the utilization of the AWCC technique in laboratory or large-scale applications requires an appropriate selection of processing parameters, including the number of particles N p and threshold values for the maximum crosscorrelation coefficient and the secondary peak ratio (Kramer et al, 2019) (figure 1d ). To facilitate the selection of processing parameters, this work explores the sensitivity of the AWCC technique through a re-analysis of previous phase-detection probe measurements (Felder and Pfister, 2017;Felder et al, 2019;Montano, 2019). The AWCC technique is detailed in section 2, followed by a description of the selected datasets (section 3) and a presentation of the sensitivity analysis (section 4).…”

Section: Adaptive Window Cross-correlation (Awcc) Techniquementioning

confidence: 99%

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Best practices for velocity estimations in highly aerated flows with dual-tip phase-detection probes

Kramer

Hohermuth

Valero

et al. 2020

International Journal of Multiphase Flow

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Dual-tip phase-detection probes can be used to measure flow properties in gas-liquid flows. Traditionally, time-averaged interfacial velocities have been obtained through cross-correlation analysis of long time-series of phase fraction signals. Using small groups of detected particles, a recently developed adaptive window cross-correlation (AWCC) technique enables the computation of pseudo-instantaneous interfacial velocities and turbulence quantities in highly aerated flows, albeit subject to some smoothing which is due to the use of a finite window duration. This manuscript provides guidance on the selection of optimum processing parameters for the AWCC technique, additionally addressing shortcomings such as velocity bias correction in turbulent flows and extrapolation of turbulence levels to single particles. The presented technique was tested for three highly turbulent air-water flows: smooth and rough-wall boundary layers (tunnel chute and stepped spillway), as well as breaking shear layer flows of a hydraulic jump. Robust estimations of mean velocities and velocity fluctuations were obtained for all flow situations, either using dual-tip conductivity or fiber optical probe data. The computation of integral time scales and velocity spectra is currently limited by the data rate and must be treated with caution.

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Remote sensing of aerated flows at large dams: proof of concept

Kramer

Felder

2021

Preprint

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High-velocity air-water flows downstream of sluice gates including selection of optimum phase-detection probe

Cited by 32 publications

References 53 publications

Flow Resistance and Energy Dissipation in Supercritical Air‐Water Flows Down Vegetated Chutes

Flow Resistance and Energy Dissipation in Supercritical Air‐Water Flows Down Vegetated Chutes

Best practices for velocity estimations in highly aerated flows with dual-tip phase-detection probes

Remote sensing of aerated flows at large dams: proof of concept

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