Name: fluid head profiles in pipes and channels
Uploaded: 2025-02-13T15:43:14.000Z
Duration: 1 min 27 s
Channel: JoVE

En un fluido que fluye a través de una tubería, la línea de energía representa la energía total del fluido, combinando la presión, la velocidad y las alturas de elevación.
Por el contrario, la línea de gradiente hidráulico muestra solo la suma de las cargas de presión y elevación, excluyendo la velocidad.
Estas líneas representan visualmente la distribución de energía y presión en un sistema de flujo de fluidos.
La diferencia entre estas líneas es la carga de velocidad; la línea de energía es siempre mayor que la línea de gradiente hidráulico durante el flujo.
En un fluido estacionario, las líneas de gradiente de energía e hidráulica coinciden.
La presión positiva ocurre cuando la línea de gradiente hidráulico está por encima de la tubería; la presión negativa ocurre cuando está por debajo, lo que puede causar problemas como la cavitación.
Mantener el gradiente hidráulico por encima de la elevación de la tubería evita problemas como el arrastre de aire y la falla estructural de la tubería.
En los sistemas de sifón, la comprensión de estas líneas garantiza la presión adecuada para mantener un flujo ininterrumpido.
El monitoreo de estas líneas ayuda a detectar fugas u obstrucciones y a diseñar sistemas para evitar golpes de ariete o reflujo.
Instrumentos como los tubos de Pitot y los piezómetros miden estas líneas, lo que ayuda en el diseño y análisis de sistemas hidráulicos en ingeniería civil.

línea de energía y línea de gradiente hidráulico

Energy Line and Hydraulic Gradient Line

Basadas en la ecuación de Bernoulli, la línea de energía (EL) y la línea de gradiente hidráulico (HGL) proporcionan representaciones gráficas de la distribución de energía en un sistema de flujo de fluido. Para flujos estables, incompresibles y no viscosos, la ecuación de Bernoulli se expresa como: <img alt="Equation 1" src="/files/ftp_upload/18039/18039_Equation_1.svg" style="text-align: center; height: 34px;"> Aquí, H es la altura total, p/γ​ es la altura de presión, V2/2g​ es la altura de velocidad y z es la altura de elevación. La línea de energía (EL) representa la altura total disponible en el flujo. Está ubicada sobre el punto de referencia e incluye los tres componentes de energía. En condiciones ideales, permanece horizontal, ya que la energía total no varía a lo largo de una línea de corriente. La elevación de la EL se puede medir utilizando un tubo de Pitot, que captura la presión de estancamiento y proporciona el valor total de energía. La línea de gradiente hidráulico (HGL) representa la altura piezométrica (p/γ+ z), que excluye la altura de velocidad. Se encuentra por debajo de la EL a una distancia vertical, que es igual a la carga de velocidad (V2/2g​). La HGL representa las variaciones de presión dentro del sistema. En tuberías presurizadas, se encuentra por encima de la tubería, mientras que en el flujo en canal abierto, coincide con la superficie del agua. Si la velocidad del fluido o el diámetro de la tubería cambian, la elevación de la HGL se ajusta en consecuencia. La carga de presión es cero en la salida de la tubería, lo que hace que la HGL coincida con la carga de elevación. Para un flujo constante y no viscoso desde un tanque, la EL y la HGL son horizontales, lo que refleja una carga constante y una presión atmosférica de salida. Las aplicaciones prácticas a menudo incorporan efectos viscosos y pérdidas, que distorsionan la EL y la HGL. Estos conceptos son cruciales para analizar las distribuciones de presión y energía en sistemas de fluidos.

Línea de energía y línea de gradiente hidráulico

En un fluido que fluye a través de una tubería, la línea de energía representa la energía total del fluido, combinando la presión, la velocidad y las alturas de elevación.
En...

Education

Educación

JoVE Core

Civil Engineering

Ingeniería Civil

Unit 1

Unidad 1

Fluid Dynamics

Dinámica de fluidos

KEY TERMS AND CONCEPTS

TÉRMINOS Y CONCEPTOS CLAVE

fluid head profiles in pipes and channels

Fluid head profiles in pipes and channels show how pressure, speed, and height change in a flowing fluid. These profiles come from Bernoulli's equation for steady, incompressible, inviscid flow. In that equation, total head includes pressure head, velocity head, and elevation head.

The energy line (EL) shows the total head available in the flow. It sits above the datum and includes all three energy parts. Under ideal conditions, the EL stays horizontal because the total energy does not change along a streamline. A Pitot tube can be used to measure the EL by capturing stagnation pressure and giving the total energy value.

The hydraulic grade line (HGL) shows the piezometric head, which is the pressure head plus the elevation head. It does not include the velocity head. The HGL lies below the EL by a vertical distance equal to the velocity head, V²/2g. It helps show pressure changes in the system.

In a pressurized pipeline, the HGL is usually above the pipe. In open-channel flow, it matches the water surface. If fluid velocity changes or the pipe diameter changes, the HGL position changes too. At a pipe outlet, pressure head is zero, so the HGL meets the elevation head.

For steady, inviscid flow from a tank, both the EL and HGL are horizontal. This reflects constant head and atmospheric pressure at the outlet. In real systems, viscous effects and losses can bend these lines. These ideas are important for reading pressure and energy in fluid systems.

Fluid Head Profiles in Pipes and Channels

fluid-head-profiles-in-pipes-and-channels

bernoulli's equation for flow along a streamline

bernoulli-s-equation-for-flow-along-a-streamline

Pressure and Speed in Bernoulli's Equation

Bernoulli's equation links pressure, speed, and height in a moving fluid along a streamline. It is used for incompressible, inviscid fluids under steady flow. The idea comes from applying Newton's second law to a small fluid element. That element feels forces from pressure differences, gravity, and changes in velocity. The resulting equation shows how fluid energy is shared. In the equation, P is pressure, ρ is fluid density, v is velocity, g is the acceleration due to gravity, and h is...

bernoulli's equation for flow normal to a streamline

bernoulli-s-equation-for-flow-normal-to-a-streamline

Pressure Changes Across Curved Streamlines

Bernoulli's equation for flow normal to a streamline describes how pressure changes across curved streamlines. When a fluid follows a curved path, the outer side of the curve experiences centrifugal force, which pushes the fluid outward. The pressure is therefore higher on the inner side, near the center of curvature, and lower farther out. The size of this pressure difference depends on the fluid's velocity and the radius of curvature. In flows with nearly straight streamlines, the pressure...

bernoulli's equation: problem solving

Venturi Meter Flow Rate from Pressure

A Venturi meter measures fluid flow rate in a pipeline by using pressure changes and Bernoulli's equation. In a sewage system, it can be used to determine wastewater flow rate by reading the pressure difference across the meter. The narrowed throat makes the fluid speed up, and that change in speed is linked to pressure drop. The first step is to find the cross-sectional areas of the pipe and the Venturi throat. These areas are needed to interpret the pressure difference shown on the pressure...

static, stagnation, dynamic and total pressure

static-stagnation-dynamic-and-total-pressure

Pitot-Static Measurement in Bernoulli Flow

Static pressure, dynamic pressure, stagnation pressure, and total pressure are key ideas in fluid dynamics. They are often explained with Bernoulli's equation. In that equation, p is static pressure, 1/2ρV^2 is dynamic pressure, γz is hydrostatic pressure or potential energy pressure, and pT is total pressure. For incompressible flow, the total pressure stays constant along a streamline. Static pressure is the pressure a fluid exerts when it is at rest, or when flowing fluid is brought to rest...

free jet

Liquid Speed from Reservoir Outlets

Free jets show how liquid moves after leaving a reservoir through an opening and flowing into the air without resistance. The jet speed is found with Bernoulli’s principle, and it depends on the height of liquid above the opening. This relationship assumes atmospheric pressure at both the reservoir surface and the jet exit. The liquid column’s height controls the speed at the nozzle because the fluid’s potential energy changes into kinetic energy during flow. As the liquid leaves the...

continuity equation

Fluid Flow and Area Changes

Fluid flow and area changes are linked by the continuity equation. For a steady flow of an incompressible fluid in a confined system, the mass flow rate stays constant. This idea is useful in nozzles, syringes, and pipes where the cross-sectional area changes. The mass flow rate is written as an equation that connects density, area, and velocity. For incompressible flow, the density stays the same, so the equation becomes simpler. When the area gets smaller, the fluid speed must increase. When...

energy line and hydraulic gradient line

Fluid head profiles in pipes and channels show how pressure, speed, and height change in a flowing fluid. These profiles come from Bernoulli's equation for steady, incompressible, inviscid flow. In that equation, total head includes pressure head, velocity head, and elevation head. The energy line (EL) shows the total head available in the flow. It sits above the datum and includes all three energy parts. Under ideal conditions, the EL stays horizontal because the total energy does not change...

design example: designing water slide

Water Slide Speed and Bernoulli's Principle

Water slide speed is controlled by Bernoulli's principle and the height of the slide. Engineers use these ideas to keep the ride exciting while making sure the water stays safe for riders. As water moves downhill, gravity makes it speed up. The water at the bottom depends on the height it starts from. A taller slide gives the water more potential energy at the top. That energy changes into kinetic energy as the water descends, so the flow becomes faster. Bernoulli's principle helps describe...

key terms and concepts

Learn how the energy line and hydraulic grade line show total head, pressure changes, and velocity effects in pipes, tanks, and open channels.

Fluid Head Profiles in Pipes and Channels | 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

Fluid Head Profiles in Pipes and Channels

Description

Transcript

Tags