Standing wave at dropshaft inlets

Wu, Jianhua; Ren, Weichen; Ma, Fei

doi:10.1016/s1001-6058(16)60765-5

Cited by 9 publications

(5 citation statements)

References 5 publications

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“…Water The k value of different positions was calculated by the simulated tangential velocity. Then combined with Equations (17) and (18), the theoretical pressure at each position can be obtained. The comparison of pressure between the theoretical value and the simulated value is shown in Figure 21, where the dotted line indicates the boundary between the forced vortex and the free vortex region.…”

Section: Theoretical Analysis Between Cross-sectional Pressure and Tamentioning

confidence: 99%

“…Pfister and Crispino [13] presented an applicable concept to a novel junction chamber combining with several inlet channels. In addition, Hager [11], Crispino and Pfister [17], and Wu et al [18] theoretically and experimentally analyzed the performance of the standing wave at the intake structure, mainly characterized by the relative height, the location and the extent.…”

Section: Introductionmentioning

confidence: 99%

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Three-Dimensional Flow of a Vortex Drop Shaft Spillway with an Elliptical Tangential Inlet

Zhou

Yin

et al. 2021

Water

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Vortex drop shaft (VDS) spillways are eco-friendly hydraulic structures used for safely releasing flood. However, due to the complexity of the three-dimensional rotational flow and the lack of suitable measuring devices, current experimental work cannot interpret the flow behavior reliably inside the VDS spillway, consequently experimental and CFD study on a VDS spillway with an elliptical tangential inlet was conducted to further discern the interior three-dimensional flow behavior. Hydraulic characteristics such as wall pressure, swirl angle, annular hydraulic height and Froude number of the tapering section are experimentally obtained and acceptably agreed with the numerical prediction. Results indicated that the relative dimensionless maximum height of the standing wave falls off nearly linearly with the increasing Froude number. Nonlinear regression was established to give an estimation of the minimum air-core rate. The normalized height of the hydraulic jump depends on the flow phenomena of pressure slope. Simulated results sufficiently reveal the three-dimensional velocity field (resultant velocity, axial velocity, tangential velocity and radial velocity) with obvious regional and cross-sectional variations inside the vortex drop shaft. It is found that cross-sectional tangential velocity varies, resembling the near-cavity forced vortex and near-wall free vortex behavior. Analytic calculations for the cross-sectional pressure were developed and correlated well with simulated results.

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Section: Theoretical Analysis Between Cross-sectional Pressure and Tamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Three-Dimensional Flow of a Vortex Drop Shaft Spillway with an Elliptical Tangential Inlet

Zhou

Yin

et al. 2021

Water

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“…The water depth steadily increases by increasing the flowrate, and the water depth doesn't increase in the intake structure (x < 0.71 m) in spite of decrease of the channel width. In a curved channel, a standing wave can be appeared due to the velocity increase [10], and the previous research [11] reported that the maximum water level may occur within the vertical shaft. However, in this channel, the water depth increase by a standing wave was not observed in the vertical shaft.…”

Section: Water Depth Measurementsmentioning

confidence: 99%

Experimental Studies on the Formation of Air-core inside the Drop Shaft

2018

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In this study, the drainage efficiency of the multi-stage intake structure, which transports flood to the underground storage, was investigated from the laboratory experiments. The multi-stage intake structure was designed based on the tangential intake and the steps on the bed were purposes to decrease the energy of approaching flow. The experimental results show that the maximum water depth was effectively decreased in the entrance of the drop shaft. The measurements results of the air core width in the drop shaft show that the flow was stably drained without the choking. Furthermore, the air core width tends to increase with the Froude number, and these results indicate that the multi-stage intake structure is applicable to convey the approaching flow with relatively high velocity.

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“…Similar dropshafts with large-angle steps or blade-shaped steps were tested by means of experimental and numerical methods, respectively, and these case studies provided some useful information about the flow characteristics in the dropshafts (Qi et al 2018;Wu et al 2018;Sun et al 2020). Attention was also paid to the standing waves formed at the inlet of such dropshafts in the literature (Wu et al 2017). However, the performance and mechanism of the energy dissipation and cavitation erosion reduction in the dropshaft are yet to be investigated to support the design.…”

Section: Introductionmentioning

confidence: 99%

Hydraulic performance of helical-step dropshaft

Ren

et al. 2021

Water Science and Technology

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Aiming to achieve energy dissipation and prevention of cavitation erosion, a kind of dropshaft in urban drainage systems, called helical-step dropshaft, is introduced in this paper. It dissipates flow energy by means of step geometry and prevent cavitation erosion through air entrainment. To verify its availability, the hydraulic characteristics of the helical-step dropshaft were experimentally investigated, including the flow regimes, the efficiency of energy dissipation, characteristics of air entrainment and pressure distribution. The results demonstrate that, even for a large discharge, flow can be discharged smoothly and steadily, and a high energy-dissipation rate of over 87% is achieved. There are three distinct flow regimes observed in the dropshaft, namely nappe flow, mixed flow and skimming flow. Moreover, there is no less than 1.6% air concentration and a reasonable pressure distribution on the step surface. This study provides an attractive alternative for the design of drop structures.

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Standing wave at dropshaft inlets

Cited by 9 publications

References 5 publications

Three-Dimensional Flow of a Vortex Drop Shaft Spillway with an Elliptical Tangential Inlet

Three-Dimensional Flow of a Vortex Drop Shaft Spillway with an Elliptical Tangential Inlet

Experimental Studies on the Formation of Air-core inside the Drop Shaft

Hydraulic performance of helical-step dropshaft

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