Pitot tube

A probe that measures fluid speed by comparing stagnation pressure with surrounding static pressure. Its pressure difference yields speed when fluid density is known.

Stagnation pressure: The pressure a moving fluid would have if brought to rest without loss. The forward-facing opening senses this pressure as flow is brought nearly to rest.
Airspeed indicator: An aircraft instrument that displays airspeed from the difference between pitot and static pressures. It converts the probe's pressure difference into a cockpit speed indication.
Fluid pressure: The normal force per unit area exerted by a fluid on a surface. The probe's operation depends on distinguishing pressure contributions in moving fluid.
Static pressure port: An opening designed to sense a fluid's static pressure with minimal influence from flow direction. Unlike the forward-facing inlet, it is oriented to avoid capturing stagnation pressure.
Static pressure: The thermodynamic pressure of a moving fluid, excluding its directed motion. Side openings or a separate tap measure this reference pressure.
Aircraft airspeed: A measure of an aircraft's speed through the surrounding air, defined in several standard forms. Pitot pressure is the primary basis for indicated airspeed.
Fluid density: The mass of fluid per unit volume. The same pressure difference implies different speeds at different densities.
Prandtl probe: A combined pitot-static probe with openings for stagnation and static pressure measurement. It is a specific probe design that packages both pressure measurements together.
Bernoulli's principle: A relation among pressure, speed, and elevation in steady ideal fluid flow. It links the stagnation-to-static pressure difference to flow speed.
Wind tunnel: A facility that drives controlled airflow around models or instruments for testing. Pitot probes measure the test-section flow speed.

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