Numerical simulation of air entrainment in uniform chute flow

Hohermuth, Benjamin; Schmocker, Lukas; Boes, Robert M.; Vetsch, David

doi:10.1080/00221686.2020.1780492

Cited by 12 publications

(5 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Despite not simulating the air-water mixture, the TPVoF may be an appropriate tool for preliminary analysis of flows with low air-concentrations (<20%), where the tracking of the free-surface is dominant. Further research should compare the efficiency of the CTPE with other successful approaches using the VoF or the mixture models combined with a sub-grid bubble model (e.g., [27,37]), in cases where the air-concentration is lower than 15-20%, or even for larger air concentrations, in light of some recent successful applications of the VoF and mixture models for highly aerated flows [16,18,24].…”

Section: Discussionmentioning

confidence: 99%

“…Commonly, lower-nappe aeration is characterized by the ratio (β) between the flowrate of air-entrained at the cavity zone (Q al ) and water flow-rate at the inlet (Q w ), see Equation (24). Q al is measured by the air flow-rate entering the cavity zone through both lateral air-vents (Figure 2).…”

Section: Lower-nappe Aerationmentioning

confidence: 99%

“…Also, the scientific community published plenty of data of physical models, allowing the calibration and validation of numerical models (e.g., [7][8][9][10][11][12][13][14]). Despite not being completely established in practical engineering, CFD is becoming a reliable and important tool, enabling the test of innovative designs quickly with cost-saving, and a detailed analysis of most phenomena in the flows (e.g., [15][16][17][18][19][20][21][22][23][24]). CFD also provides valuable information in the design and validation stages, predicting problems.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Do the Volume-of-Fluid and the Two-Phase Euler Compete for Modeling a Spillway Aerator?

Mendes

Lara

Viseu

2021

Water

View full text Add to dashboard Cite

Spillway design is key to the effective and safe operation of dams. Typically, the flow is characterized by high velocity, high levels of turbulence, and aeration. In the last two decades, advances in computational fluid dynamics (CFD) made available several numerical tools to aid hydraulic structures engineers. The most frequent approach is to solve the Reynolds-averaged Navier–Stokes equations using an Euler type model combined with the volume-of-fluid (VoF) method. Regardless of a few applications, the complete two-phase Euler is still considered to demand exorbitant computational resources. An assessment is performed in a spillway offset aerator, comparing the two-phase volume-of-fluid (TPVoF) with the complete two-phase Euler (CTPE). Both models are included in the OpenFOAM® toolbox. As expected, the TPVoF results depend highly on the mesh, not showing convergence in the maximum chute bottom pressure and the lower-nappe aeration, tending to null aeration as resolution increases. The CTPE combined with the k–ω SST Sato turbulence model exhibits the most accurate results and mesh convergence in the lower-nappe aeration. Surprisingly, intermediate mesh resolutions are sufficient to surpass the TPVoF performance with reasonable calculation efforts. Moreover, compressibility, flow bulking, and several entrained air effects in the flow are comprehended. Despite not reproducing all aspects of the flow with acceptable accuracy, the complete two-phase Euler demonstrated an efficient cost-benefit performance and high value in spillway aerated flows. Nonetheless, further developments are expected to enhance the efficiency and stability of this model.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Lower-nappe Aerationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Do the Volume-of-Fluid and the Two-Phase Euler Compete for Modeling a Spillway Aerator?

Mendes

Lara

Viseu

2021

Water

View full text Add to dashboard Cite

show abstract

“…Jesudhas et al (2018) used the large eddy simulation method to analyze the hydrojump process and obtained flow field information such as turbulence structure characteristics. Hohermuth et al (2021) used Flow‐3D to simulate self‐aerated water flow within a certain slope range, and the error was only about 10%.…”

Section: Introductionmentioning

confidence: 99%

Aeration strength analysis of overflow weir in siphon well based on numerical simulation of water–air two‐phase flow

Liu,

Lin,

Huang

et al. 2023

River

View full text Add to dashboard Cite

The phenomenon of water aeration is serious after the overflow weir in the siphon well at the cooling water circulation system of coastal power plants. At present, designing special hydraulic structures is an effective way to reduce the intensity of aeration. In this paper, three engineering structure schemes were designed, and the three‐dimensional Realizable k–ε turbulence model was used. The volume of fluid method was introduced to capture the free water surface, and the unstructured grid was used to construct the two‐phase turbulent flow field. The aeration concentration and pressure distribution, obtained by numerical simulation, were basically consistent with the physical model test results. The results showed that the flow field at the orifice plates of cases 1 and 2 changed drastically, and the turbulent kinetic energy downstream of the orifice plate decreased with the increase of the number of holes. As for case 3, it showed that the high‐speed water flow fell into the water cushion pool, tumbling and sucking up a lot of air, and the turbulent kinetic energy and Reynolds stress were significantly greater than the other two cases. The hydraulic structure changed the cavitation characteristics of the downflow water, and the sequence of aeration concentration of the horizontal section was case 3 > case 1 > case 2. The aeration concentration was only 9.18%–17.86% in case 2. The aeration concentration at stable time is expressed as a function of the relative water depth y/y90 and the turbulent diffusion coefficient D. The distribution formula of aeration concentration was established, and its validity was verified by literatures. The results of this study will provide a certain reference for in‐depth analysis of water–air mixing motion characteristics, and simultaneously, it will have a guiding significance for the design of siphon well defoaming engineering.

show abstract

“…Based on the VOF model, Li Zhigao [12] simulated water-air mixing in open channel water flow and in front of a gate, and calculated the shape of the water-air interface, the distribution of water-air content, and the velocity field, pressure field, turbulent kinetic energy, and turbulent dissipation rate distribution of the flow field. Hohermuth et al [13] used a uniformly aerated water flow to calibrate the mixing model, solved the mixed Reynolds mean N-S equation, and used different sub-grid air transport models to evaluate the effects of drag coefficient, correction model, and bubble diameter. Zhou Ling et al [14][15][16] simulated the water-gas two-phase interaction in a pipeline containing trapped air mass by using a three-dimensional CFD method, and showed the dynamic change process through the water-gas two-phase distribution diagram.…”

Section: Introductionmentioning

confidence: 99%

Gas Loss Mechanism in the High-Pressure Air Cushion Surge Chamber of Hydropower Station for Transient Process

Xia

Wang

Du³

et al. 2023

Water

View full text Add to dashboard Cite

Water–air interaction (mixing of gas and water and gas dissolution into water) is one of the main reasons for gas loss in air cushion surge chambers. With the increase of water head in hydraulic power generation systems, the heat and mass transfer process at the water–air interface under high-pressure conditions intensifies, and the water–air interaction is further strengthened. If some gas is mixed/dissolved in water and enters downstream pipelines, it will affect the safety of the unit. At present, there has been no theoretical or systematic research on gas loss and related water gas two-phase flow in air cushion surge chambers under high-pressure conditions. Therefore, this article established an air loss model for an air cushion surge chamber based on the VOF model and gas–liquid mass transfer theory. We analyzed the mechanism of gas loss in the gas chamber through simulation and quantitatively expressed the gas loss. The results indicate that during a typical large fluctuation process, the gas–liquid mass transfer process at the water–air interface, air mass, and vortex is very strong, with a pressure chamber of approximately 923.89 m3. The gas dissolved in water enters the water diversion system, with a length of 28.75 m3. High pressure gas enters the water diversion system in the form of air masses. When considering the water inlet on the right side of the air chamber, the total gas loss in the air chamber is slightly lower (854.18 m3) and no mixed air mass was detected entering the connecting pipe.

show abstract

Numerical simulation of air entrainment in uniform chute flow

Cited by 12 publications

References 35 publications

Do the Volume-of-Fluid and the Two-Phase Euler Compete for Modeling a Spillway Aerator?

Do the Volume-of-Fluid and the Two-Phase Euler Compete for Modeling a Spillway Aerator?

Aeration strength analysis of overflow weir in siphon well based on numerical simulation of water–air two‐phase flow

Gas Loss Mechanism in the High-Pressure Air Cushion Surge Chamber of Hydropower Station for Transient Process

Contact Info

Product

Resources

About