pitottype

Pitot-type refers to a class of fluid velocity sensors that determine flow speed by measuring pressures from a facing opening and comparing them to the surrounding static pressure. The most common implementation is the Pitot tube, often used in conjunction with static ports to form a Pitot-static system. The device converts kinetic energy of the flowing fluid into a measurable pressure difference, which can then be translated into velocity.

Principle and relationship. When flow enters the Pitot opening, it stagnates, yielding stagnation pressure p_t. Static pressure p_s is measured by separate side ports. The dynamic pressure q = p_t − p_s is related to velocity by q ≈ ½ ρ v^2 for incompressible flows, where ρ is fluid density. At higher speeds, compressibility effects require corrections using isentropic relations or specific calibration. The result can be wired to a gauge, a pressure transducer, or an electronic instrument for display.

Construction and usage. A Pitot-type sensor typically consists of a hollow tube facing the flow, with a central inlet for total pressure and side holes for static pressure. It is connected to pressure sensors or manometers. In aviation, the Pitot-static system feeds the airspeed indicator and other avionics, while in wind tunnels and industrial settings it provides velocity measurements in pipes or open channels.

Advantages and limitations. Pitot-type sensors have no moving parts and offer fast response and robustness. They require clean, undistorted flow and proper orientation; readings degrade with icing, contamination, or flow distortion and must be calibrated for density, temperature, and compressibility.

History and scope. The Pitot tube was invented by Henri Pitot in the 18th century for river flow measurement and was later adapted into the Pitot-static systems widely used in aviation and experimental fluid dynamics. See also Pitot tube and airspeed indicator.