Name: sluice gate water pressure and reaction force
Uploaded: 2025-02-13T15:43:22.000Z
Duration: 1 min 11 s
Channel: JoVE

Une vanne est une barrière verticale qui contrôle l’écoulement de l’eau dans un canal.
Pour calculer les forces agissant sur une écluse, considérons que l’eau qui s’écoule sous la vanne.
Les forces dépendent de la profondeur de l’eau en amont et en aval.
Du côté amont, la profondeur est de z1, et du côté aval, la profondeur est de z2.
La différence de pression entre les deux côtés crée une force nette sur le portail.
En utilisant le principe de Bernoulli, la vitesse de l'eau sous la vanne, V2, peut être calculée sur la base de la différence de pression et de la chute de hauteur.
La force de réaction sur la vanne est calculée à partir de la force hydrostatique agissant en raison de la colonne d’eau des deux côtés.
La force est plus importante lorsque le portail est fermé en raison de la plus grande différence de pression.
Lorsque la vanne est ouverte, la force de réaction diminue car l’eau s’écoule librement sous la vanne, réduisant ainsi la différence de pression hydrostatique nette.
Ce principe permet de déterminer la force d’ancrage nécessaire pour maintenir la porte en place pendant le fonctionnement.

exemple de conception: forces dans une vanne d'écluse

Design Example: Forces in Sluice Gate

En génie hydraulique, les vannes d'écluse sont essentielles pour gérer le débit d'eau dans les canaux, les réservoirs et les systèmes d'irrigation. Les vannes d'écluse, agissant comme des barrières verticales, régulent l'eau en ajustant la hauteur d'ouverture de la vanne, ce qui modifie la vitesse et la pression de l'eau qui s'écoule sous la vanne. Il est essentiel de comprendre les forces impliquées pour concevoir des vannes d'écluse capables de résister aux différences de pression dynamiques, en particulier lorsque la vanne est fermée ou partiellement ouverte.

Les variables clés dans l'analyse des forces des vannes d'écluse comprennent la profondeur en amont z_1​ et la profondeur en aval z_2​. Lorsque la vanne est fermée, la profondeur de l'eau est plus grande du côté amont, ce qui crée un différentiel de pression important à travers la vanne. Cette différence de pression produit une force nette, qui nécessite un système d'ancrage pour maintenir la vanne en place en toute sécurité. La pression hydrostatique exercée du côté amont est proportionnelle à la profondeur de l'eau et à la force gravitationnelle, tandis que la pression en aval dépend de z_2​. Le gradient de pression résultant à travers la vanne crée une force nette qui pousse contre elle vers le côté aval.

Lorsque la vanne est partiellement ouverte, l'eau s'écoule en dessous et le principe de Bernoulli peut être utilisé pour déterminer la vitesse en aval, V_2​.

<img alt="Equation 1" src="/files/ftp_upload/18056/18056_Equation_1.svg" style="text-align: center; height: 90px;">


Étant donné les profondeurs en amont et en aval, le principe relie la variation de pression due aux différences de hauteur d'eau, ce qui permet de calculer V_2 en fonction des différences de hauteur et des gradients de pression. Cet écoulement diminue la pression exercée sur la vanne en permettant le mouvement plutôt que l'accumulation, réduisant ainsi la force nette lorsque l'eau s'écoule librement.

La force de réaction totale sur la vanne est principalement influencée par la force hydrostatique de la colonne d'eau en amont, qui est à son maximum lorsque la vanne est complètement fermée. Lorsque la vanne s'ouvre et que l'eau s'écoule en dessous, la réduction du différentiel de pression diminue la force de réaction.

<img alt="Equation 2" src="/files/ftp_upload/18056/18056_Equation_2.svg" style="text-align: center; height: 90px;">

Exemple de conception: forces dans une vanne d'écluse

Une vanne est une barrière verticale qui contrôle l’écoulement de l’eau dans un canal.
Pour calculer les forces agissant sur une écluse, considérons que l’eau qui s’écoule sous ...

Education

Enseignement

JoVE Core

Civil Engineering

Génie civil

Unit 1

Unité 1

Finite Control Volume Analysis

Analyse par volumes de contrôle finis

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

sluice gate water pressure and reaction force

Sluice gates control water flow in channels, reservoirs, and irrigation systems. They work as vertical barriers with an opening that can be raised or lowered. Changing the opening height changes the water velocity and pressure below the gate.

The forces on a sluice gate depend on the water depths upstream and downstream, written as z1 and z2. When the gate is closed, the upstream water depth is greater. That creates a strong pressure difference across the gate and a net force toward the downstream side. In that case, the gate needs an anchoring system to keep it secure.

The pressure on the upstream side is hydrostatic pressure, which depends on water depth and gravity. The downstream pressure depends on z2. Together, these pressures create the pressure gradient that pushes on the gate.

When the sluice gate is partially open, water flows beneath it. Bernoulli's principle can then be used to find the downstream velocity, V2, from the upstream and downstream depths. As the water moves through the opening instead of building up, the pressure difference becomes smaller and the reaction force on the gate decreases. The total reaction force is therefore highest when the gate is fully closed and lower as the gate opens.

Sluice Gate Water Pressure and Reaction Force

sluice-gate-water-pressure-and-reaction-force

conservation of mass in finite cotrol volume

conservation-of-mass-in-finite-cotrol-volume

Continuity Equation for a Fixed Control Volume

The continuity equation describes conservation of mass for a fixed control volume. In fluid mechanics, a system is a collection of the same contents over time, and its mass stays constant. That idea is the starting point for deriving the equation. To analyze flow, a fixed, non-deforming control volume is chosen so it matches the system at one instant. The Reynolds transport theorem then links the system to the control volume. It shows that the rate of change of system mass has two parts: mass...

conservation of mass in fixed, nondeforming control volume

conservation-of-mass-in-fixed-nondeforming-control-volume

Continuity and Velocity in Pipe Flow

Conservation of mass explains how fluid moves through a fixed control volume such as a pipe or duct. In a fixed, nondeforming control volume, the total mass stays constant unless mass enters or leaves through the control surfaces. For steady, incompressible flow, the mass entering the system equals the mass leaving it. A sewer pipe is a useful example of this idea. It can be treated as a fixed control volume with inlet and outlet control surfaces around the flow region. Because the fluid is...

conservation of mass in moving, nondeforming control volume

conservation-of-mass-in-moving-nondeforming-control-volume

Stormwater Detention Basin Mass Balance

Stormwater detention basins use mass balance to manage runoff during heavy rainfall. These basins are especially important in urban areas, where impervious surfaces can increase flooding risk. Engineers use the conservation of mass to track how water enters, is stored in, and leaves the basin. In a detention basin, the control volume is the water inside the basin. Its boundaries are the basin walls, the inflow pipes, and the outflow structures. During a rain event, water comes in through the...

linear momentum in control volume

Momentum Balance for Fluid Control Volumes

Linear momentum balance for a fluid control volume links Newton’s second law to moving fluid. The law says that the rate of change of linear momentum equals the sum of the external forces acting on the system. In a fluid system, this idea helps explain how motion and force are related. A control volume can match the fluid system at a specific moment. When that happens, the forces on the control volume and the system are the same. Reynolds transport theorem explains this connection by splitting...

application of the linear momentum equation

application-of-the-linear-momentum-equation

Forces in a 180° Pipe Bend

Forces in a 180-degree pipe bend can be found by applying the linear momentum equation to flowing water. The pipe has a constant cross-sectional area of 0.01 square meters, and the water moves at 15 meters per second. The pressure at the inlet is 0.2 megapascals, and the pressure at the outlet is 0.16 megapascals. The goal is to find the force components in the x and y directions that hold the bend in place. In this case, the flow is only in the y direction at both the entrance and the exit.

moment-of-momentum equation

Wind Turbine Torque and Angular Momentum

The moment-of-momentum equation helps explain how wind turbine blades create torque. Torque is the turning effect of a force around an axis. In rotating systems, this equation links the motion of the wind with the force acting on it. The equation begins with Newton's second law for a fluid particle. That law says the rate of change of linear momentum equals the external force on the particle. To find torque, the position of the particle relative to the rotation axis is combined with that force.

conservation of energy in control volume

Turbine Work from Energy Changes

A turbine can turn fluid energy into shaft work when flow passes through a control volume. The fluid enters the turbine at one point and leaves at another. Under steady-flow conditions, there is no energy buildup inside the control volume, so the stored energy does not change with time. This steady-flow setup makes the energy equation simpler. The turbine is treated as doing mechanical work, and heat transfer is taken as negligible, so Q̇ is approximately zero. The flow at the inlet and outlet...

application of the energy equation

Centrifugal Pump Flow Rate Calculation

Centrifugal pump flow rate can be calculated with the energy equation. In this problem, water moves between two reservoirs at different elevations, and the pump provides the energy needed for the transfer. The pump input is 7500 joules per second, the elevation difference is 10 meters, and the head loss from friction and other resistances is 5 meters. Both reservoirs are open to the atmosphere, so the pressure at the inlet and outlet is the same. That means the pressure terms in the energy...

design example: forces in sluice gate

Sluice gates control water flow in channels, reservoirs, and irrigation systems. They work as vertical barriers with an opening that can be raised or lowered. Changing the opening height changes the water velocity and pressure below the gate. The forces on a sluice gate depend on the water depths upstream and downstream, written as z1 and z2. When the gate is closed, the upstream water depth is greater. That creates a strong pressure difference across the gate and a net force toward the...

key terms and concepts

Learn how upstream and downstream water depths affect pressure, flow speed, and reaction force on a sluice gate when it is closed or partially open.

Sluice Gate Water Pressure and Reaction Force | JoVE K12

JoVE Core Civil Engineering provides a foundational exploration of essential construction materials in civil engineering, focusing on bricks, stones, steel, wood, and concrete through easy-to-understand animated videos. This collection covers the properties, manufacturing processes, and practical applications of these materials. Additionally, the accompanied science-in-action videos demonstrate the research experiments performed in laboratories.

civil engineering

Sluice Gate Water Pressure and Reaction Force

Description

Transcript

Tags