Step cavity and gabion aeration on a gabion stepped spillway

Zhang, Gangfu; Chanson, Hubert

doi:10.14264/uql.2014.37

Cited by 5 publications

(5 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2b & 2c). The interfacial velocity data in the free-surface flow presented some self-similar shape (Zhang and Chanson 2014). In the mainstream, the velocity profiles were close to a power law distribution for y < Y 90 where Y 90 is the characteristic elevation where C = 0.90.…”

Section: Air-water Flow Propertiesmentioning

confidence: 72%

“…Altogether the interactions between seepage and free-surface flows were significant, leading to a complex cavity recirculation flow pattern and lesser flow resistance on gabion stepped chutes compared to smooth stepped chutes. Felder and Chanson (2011), Guenther et al (2013), Wüthrich andChanson (2014) ZHANG, G., andCHANSON, H. (2016). " Gabion Stepped Spillway: Interactions between Free-Surface, Cavity, and Seepage Flows."…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Gabion Stepped Spillway: Interactions between Free-Surface, Cavity, and Seepage Flows

Zhang

Chanson

2016

J. Hydraul. Eng.

Self Cite

View full text Add to dashboard Cite

On a gabion stepped chute, the steps contribute to the dissipation of turbulent kinetic energy, freesurface aeration may be intense and there are complex interactions between the free-surface flow and seepage motion. Detailed measurements were conducted in a relatively large-size gabion stepped spillway model. Using a combination of high-speed movies and phase-detection probe measurements, the air-water flow properties in the step cavities and in the gabions were documented. Strong air-water exchanges between seepage and stepped cavity flows were observed. The data showed a complex bubbly seepage motion in the gabions, associated with a high level of interactions between seepage and free-surface flows, leading to a modification of the step cavity recirculation and lesser flow resistance.

show abstract

Section: Air-water Flow Propertiesmentioning

confidence: 72%

Section: Resultsmentioning

confidence: 99%

Gabion Stepped Spillway: Interactions between Free-Surface, Cavity, and Seepage Flows

Zhang

Chanson

2016

J. Hydraul. Eng.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The latter increase is likely caused by the convective acceleration due Note it is also possible to estimate Equation (6.51) from the phase-detection probe data alone: The present data reveal a positive correlation between the residual head and discharge. In comparison to recent literature (Felder and Chanson 2011b, Zhang and Chanson 2014 In a stepped chute, the steps generate significant form losses that account for the majority of the total energy dissipation (Chanson 2001b. By convention, the flow resistance in quasi-smooth skimming flows may be expressed in terms of the Darcy-Weisbach friction factor (Rajaratnam 1990, Chanson 2001b where Sf is the slope of the total head line.…”

Section: U D C E C E C E Udmentioning

confidence: 93%

Free-Surface Aeration, Turbulence, and Energy Dissipation on Stepped Chutes with Triangular Steps, Chamfered Steps, and Partially Blocked Step Cavities

Zhang¹

Self Cite

View full text Add to dashboard Cite

The present thesis work contains investigations of the two-phase flow properties and energy dissipation mechanisms in a 45° steep chute lined with various types of stepped macro-roughness, including one configuration with triangular flat steps, one with chamfered steps, and three with partial step cavity blockages. The study was conducted in large-size physical models with an emphasis on the skimming flow regime subject to minimal scale effects. Detailed two-phase flow patterns were documented using an ultra-high-speed video camera and processed with advanced computer vision techniques. Both the developing clear-water flow region and the fully-developed aerated flow region were investigated.In the clear water flow region, the free-surface curvature was pronounced notably at smaller A novel setup consisting of a dual-tip phase detection probe and a total pressure transducer was proposed to enable separation of the water-phase properties from the mixture. The system allowed a better assessment of the water phase turbulence properties, which displayed similar levels of fluctuations to those in the clear water flow region. The same setup was used to appraise the energy dissipation performance of each model, with an average level of 50% energy dissipation found in all but the chamfered chute at large discharges. Direct total head measurements by the transducer appeared to be of superior quality compared to those inferred from phase-detection probe data alone, which were shown to have typically overestimated the energy dissipation potential.iii Comparison between different models revealed relatively larger sensitivities of the free-surface aeration than of the energy dissipation performance to the roughness density and the step shape.Sharp edges with a smaller roughness density appeared to improve air-entrainment, which could be linked to the state of vortex shedding determined by the roughness. The chamfered steps increased the skin friction contribution to the total drag, which was associated with a delayed onset of aeration and an energy dissipation performance that scaled poorly with an increasing discharge. Overall, the flow processes more resembled those over obstacles, which might demand investigations on an individual basis.iv Declaration by authorThis thesis is composed of my original work, and contains no material previously published or written by another person except where due reference has been made in the text. I have clearly stated the contribution by others to jointly-authored works that I have included in my thesis.

show abstract

“…5, relationships were suggested for estimating the flow regimes limits on the gabion stepped weirs (normal steps) as shown in Table 4. Most studies such as (Zhang and Chanson, 2014; Wuthrich and Chanson 2015; Zhang and Chanson, 2015) used y c /h s to obtain the flow regime limits instead of the drop number [17,18,19]. This could be correct on the gabion spillways.…”

Section: Flow Regimementioning

confidence: 99%

“…The onset of the skimming flow on the gabion stepped weirs can be determined using formulae obtained by (Wuthrich and Chanson, 2015, Zhang and Chanson, 2015, Zhang and Chanson, 2014) [16][17][18] as presented in Table 1.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Effect of Downstream Slope and Rockfill Materials on Flow Regimes over Gabion Stepped Weirs

Alabas¹,

Jahad²,

Al-Ameri³

et al. 2023

Pol. J. Environ. Stud.

View full text Add to dashboard Cite

It is important to determine the limits of flow regimes in the design of stepped weirs because of the hydraulic performance of each regime. The present study investigates the effect of downstream slope and rock fill materials on flow regimes in gabion stepped weirs. Nine physical models of gabion weirs were used in the experiments. The models' downstream slopes ranged from 1:05 to 1:4 V:H. In addition, two types of rockfill materials: crushed stone of 0.42 porosity and rounded gravel of 0.38 porosity were used to study the effect of rockfill materials on flow regimes. The nominal size of the crushed stone was (37.5 mm -13.2 mm) D50 = 23 mm and the nominal size of the rounded gravel was (26.5 mm -13.2 mm) D50 = 16 mm. Each model has been tested with ten runs for discharge per unit width ranging (from 0.006 to 0.105 m 3 /sec. m) to cover all flow conditions and flow regimes. The onset of each flow regime for all physical models has been observed. The experimental data of the gabion stepped weirs have been used to develop equations to estimate the onset of each flow regime. The coefficient of correlation (R) of the developed equations ranged between 0.95 to 0.97. The results indicated on the steeper downstream slope models (1:0.5, 1:0.83), there is interference between the nappe and transition flow regimes. The nappe flow regime has not appeared on all steps at the same

show abstract

Step cavity and gabion aeration on a gabion stepped spillway

Cited by 5 publications

References 16 publications

Gabion Stepped Spillway: Interactions between Free-Surface, Cavity, and Seepage Flows

Gabion Stepped Spillway: Interactions between Free-Surface, Cavity, and Seepage Flows

Free-Surface Aeration, Turbulence, and Energy Dissipation on Stepped Chutes with Triangular Steps, Chamfered Steps, and Partially Blocked Step Cavities

Investigation of the Effect of Downstream Slope and Rockfill Materials on Flow Regimes over Gabion Stepped Weirs

Contact Info

Product

Resources

About