Name: pitot-static measurement in bernoulli flow
Uploaded: 2026-01-30T03:08:30.000Z
Duration: 1 min 24 s
Channel: JoVE

ベルヌーイの原理では、全圧力は流体システムの流線に沿って一定に保たれ、静的、動的、および位置エネルギー圧力の合計であると述べています。
静圧は、静止している流体によって加えられる力であり、パイプラインや給水システムで一般的に観察されます。
これは、流体の高さと密度に依存し、流体と接触する表面に対して垂直に作用します。
動圧は流体の速度に関連し、運動によるエネルギーを表します。
これは、雨水排水や高速の河川水路など、高速で移動する流体を含むシステムを設計する上で非常に重要です。
停滞圧力は、流体が静止したときに発生し、静圧と動圧が組み合わされます。
これは、ダムの表面やタービンブレードなど、流体の速度がゼロに低下する停滞点で測定されます。
静止圧力、動圧、停滞圧力のバランスを理解することは、流体システムの圧力変化とエネルギーを管理するのに役立ちます。
これらの圧力は、さまざまな土木工学アプリケーションでの対気速度と流体の流れの計算に重要なピトー静圧管などのデバイスを使用して測定されます。

静圧、よどみ、動圧、総圧

静圧、よどみ、動圧、総圧の概念は流体力学の基本であり、ベルヌーイの方程式を使用して説明されることがよくあります。

<img alt="Equation 1" src="/files/ftp_upload/18036/18036_Equation_1.svg" style="text-align: center; height: 26px;">

 ここで、p は静圧、1/2⍴V^2 は動圧、γz は静水圧または位置エネルギー圧、p_T は総圧で、非圧縮性の流れの流線に沿って一定です。

 1. 静圧 (p): これは静止している流体によって加えられる圧力、または流れる流体が運動方向に静止しているかのように感じる圧力です。これは、流れに挿入されたプローブまたはピエゾメータチューブを使用して測定されます。

 2. 動圧 (1/2⍴V^2): これは流体の速度による圧力上昇を表します。これは、流体の単位体積あたりの運動エネルギーとして解釈できます。

 3. よどみ点圧力 (p_s): よどみ点における静圧と動圧の合計で、流体の速度がゼロになります:

<img alt="Equation 2" src="/files/ftp_upload/18036/18036_Equation_2.svg" style="text-align: center; height: 26px;">

 4. 総圧 (p_T): 静圧、動圧、静水圧の合計です。流線に沿って:

 ピトー静圧管はよどみ点圧力 (p_s) と静圧 (p) を測定します。差を計算することで、流体の速度を決定できます:

<img alt="Equation 3" src="/files/ftp_upload/18036/18036_Equation_3.svg" style="text-align: center; height: 34px;">

 航空の対気速度測定などの用途では、ピトー静圧管の正確な位置合わせと配置が重要です。位置合わせがずれたり、詰まったりすると、誤った測定値が出て、運用上の安全性に影響する可能性があります。

ベルヌーイの原理は、全圧力が流体システムの流線に沿って一定に保たれ、静的、動的、および...

static-stagnation-dynamic-and-total-pressure

Education

JoVE Core

Civil Engineering

土木工学

Unit 1

ユニット1

Fluid Dynamics

流体力学

KEY TERMS AND CONCEPTS

主要用語と概念

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 in the direction of motion. It can be measured with a probe placed in the flow or with a piezometer tube. Dynamic pressure comes from the fluid's speed. It represents the pressure rise due to motion, and it can also be viewed as the kinetic energy per unit volume of the fluid.

Stagnation pressure is the pressure at a stagnation point, where the fluid velocity becomes zero. It equals the sum of static pressure and dynamic pressure. Total pressure includes static, dynamic, and hydrostatic pressure. Along a streamline, this total remains constant for incompressible flow.

A Pitot-static tube measures stagnation pressure and static pressure. The difference between these two readings can be used to determine fluid velocity. This measurement is important in applications such as airspeed sensing in aviation. For accurate results, the Pitot-static tube must be aligned and placed correctly, because misalignment or blockage can produce incorrect readings and affect safety.

Pitot-Static Measurement in Bernoulli Flow

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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 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

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 static, dynamic, stagnation, and total pressure relate to Bernoulli's equation and how a Pitot-static tube can be used to measure flow speed.

Pitot-Static Measurement in Bernoulli Flow | 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

Pitot-Static Measurement in Bernoulli Flow

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