PitotRöhren

A Pitot tube is a crucial instrument used in fluid dynamics to measure fluid flow velocity. It consists of a thin tube pointing directly into the flow, with a small opening at the tip. This opening measures the stagnation pressure, which is the pressure of the fluid when it is brought to rest. The main body of the tube contains one or more side openings, typically located perpendicular to the direction of flow. These openings measure the static pressure, which is the pressure of the fluid when it is not disturbed by the instrument.

The difference between the stagnation pressure and the static pressure is known as the dynamic pressure. According to Bernoulli's principle, the dynamic pressure is directly related to the kinetic energy of the fluid, and therefore its velocity. The relationship is expressed by the formula: dynamic pressure = 1/2 * density * velocity^2. By measuring both static and stagnation pressures and knowing the fluid's density, the velocity can be calculated.

Pitot tubes are widely used in aviation to determine airspeed. Airspeed indicators in aircraft are essentially calibrated Pitot tubes, displaying the calculated airspeed. They are also employed in various engineering applications, such as measuring wind speed in meteorology, airflow in ventilation systems, and water flow in hydraulic systems. Despite their simplicity, Pitot tubes are highly accurate when properly installed and maintained, and are a fundamental tool for understanding and quantifying fluid motion.