Flow kinematics with oppositely rotating coaxial layers

Orekhov, Genrikh

doi:10.1051/e3sconf/20199705051

“…The viscosity of the medium has a great influence on the diffusion of circulation in the counter-vortex flow. Let's return to expression (18). Here, the viscosity is present in the Re number.…”

Section: Ro Ro    mentioning

confidence: 99%

“…Among the energy dissipation methods of the flow spilled with its swirling, the countervortex method stands out, making it possible to effectively dissipate the high-velocity flow energy in a rather short section of the flow conductor [16,17,18]. It must be said here that a counter-vortex flow is an artificially created flow in which oppositely swirling layers of fluid or gas interact in a circular cylindrical chamber.…”

Section: Introductionmentioning

confidence: 99%

Circumferential velocities in laminar and turbulent counter-vortex flow

Orekhov

2023

E3S Web of Conf.

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Knowledge of the parameters of fluid movement is essential in the designing and operating various technological processes in various technical applications. These processes play a special role in hydro engineering, where the structures of water works are directly subjected to static and dynamic forces from the side of the water flow. The operation of hydraulic turbines, spillway and water transport systems, and other hydraulic structures is directly connected with understanding the behavior of a fluid in various regimes of movement. This report is devoted to the study of a special type of fluid and gas flow, which is called counter-vortex flow. The report compares the results of the distribution of circumferential velocities with a laminar and turbulent pattern of fluid movement. The results of the laminar flow regime were obtained using a mathematical model, and the turbulent regime on a physical model using laser technologies. Such a comparison allows one to assess two approaches in determining the kinematic structures of a complicated flow. The parameters for the viscous fluid laminar flow were determined based on the traditional system of Navier-Stokes equations by determining the dependence of the circumferential component of the total velocity at the given initial circulations and angular flow velocity. A physical model was made and equipped with a set of measuring equipment to obtain the distribution of velocities in the turbulent flow. The comparison showed that the distributions of velocities for the considered flow regimes depending on the channel radius have close coincidence. In contrast, the transformation length-wise of the active zone of the flow is significant.

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“…For example, researchers have recently used experimental models to investigate swirled flows with oppositely rotating layers in a high-head spillway structure to dissipate energy of high-velocity flows (Orekhov 2019). Newer, more efficient trash racks are being proposed and tested in laboratory flumes to improve trash removal and water passage efficiency while preventing the rack from clogging (Itsukushima et al 2016).…”

Section: Water Conveyancesmentioning

confidence: 99%

Needs and Opportunities for Testing of Hydropower Technology Innovations

Musa

¹

,

Smith²,

Sasthav

³

et al. 2022

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Despite hydropower's status as a well-established technology, changes in the global energy sector have prompted a variety of necessary hydropower technological innovations. Examples include efficient lowhead turbines, more flexible and dispatchable hydropower and pumped storage systems to complement variable and intermittent renewable resources, and technologies providing higher environmental performance. However, while innovative technologies are currently being proposed to meet these development challenges, small hydropower facility owners do not have sufficient risk-bearing capacity to adopt new, unvalidated technologies. This discourages manufacturers from bringing nascent technologies to market and stalls the technological growth of the sector. To reduce the risks associated with new technologies and promote further innovation, systemic (and sometimes unconventional) validation activities and new testing capabilities for hydropower are highly desired. These testing capabilities must demonstrate the safety, environmental acceptability, reliability, and performance of innovative technologies to quantify their value compared with existing technologies. Establishing these capabilities through dedicated testing facilities will be key to promoting hydropower growth in the United States.Following direction from the House Energy and Water Development Committee, the US Department of Energy's Water Power Technologies Office (WPTO) has been tasked with understanding the state of hydropower testing in the United States. This scoping report discusses the needs and opportunities of hydropower testing in the United States, with a specific focus on small hydropower. Future developments will likely mostly target low-head sites with less than 30 ft (9.1 m) from new stream-reach developments, non-powered dam retrofits, and rehabilitation/upgrade of existing plants.Based on emerging technology trends, testing gaps evaluation, and stakeholder inputs, four overarching thematic challenges were identified for testing hydropower innovations: 10

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Circumferential velocities in laminar and turbulent counter-vortex flow

Orekhov¹

2023

AIP Conference Proceedings

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0

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Knowledge of the parameters of fluid movement is essential in the designing and operating various technological processes in various technical applications. These processes play a special role in hydro engineering, where the structures of water works are directly subjected to static and dynamic forces from the side of the water flow. The operation of hydraulic turbines, spillway and water transport systems, and other hydraulic structures is directly connected with understanding the behavior of a fluid in various regimes of movement. This report is devoted to the study of a special type of fluid and gas flow, which is called counter-vortex flow. The report compares the results of the distribution of circumferential velocities with a laminar and turbulent pattern of fluid movement. The results of the laminar flow regime were obtained using a mathematical model, and the turbulent regime on a physical model using laser technologies. Such a comparison allows one to assess two approaches in determining the kinematic structures of a complicated flow. The parameters for the viscous fluid laminar flow were determined based on the traditional system of Navier-Stokes equations by determining the dependence of the circumferential component of the total velocity at the given initial circulations and angular flow velocity. A physical model was made and equipped with a set of measuring equipment to obtain the distribution of velocities in the turbulent flow. The comparison showed that the distributions of velocities for the considered flow regimes depending on the channel radius have close coincidence. In contrast, the transformation length-wise of the active zone of the flow is significant.

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Flow kinematics with oppositely rotating coaxial layers

Cited by 3 publications

References 14 publications

Circumferential velocities in laminar and turbulent counter-vortex flow

Circumferential velocities in laminar and turbulent counter-vortex flow

Needs and Opportunities for Testing of Hydropower Technology Innovations

Circumferential velocities in laminar and turbulent counter-vortex flow

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