ENGINEERING – PIPE FLOW & WATER UPPLY CALCULATOR
Pitot Tube Velocity
A precise tool.
What is the Pitot Tube Velocity & How does it work?
A Pitot tube consists of a forward‑facing opening that measures the total (stagnation) pressure of a fluid flow. When the fluid is brought to rest at the tube tip, its kinetic energy is converted into pressure energy, allowing the instrument to capture the combined static and dynamic pressures. The difference between the stagnation pressure (P_0) and the static pressure (P_s) is directly related to the fluid velocity. By applying Bernoulli’s equation for incompressible flow, the velocity can be expressed as (v = sqrt{frac{2,(P_0 – P_s)}{rho}}), where (rho) is the fluid density. In practice, accurate velocity measurement requires careful alignment of the tube with the flow direction and compensation for temperature‑dependent density variations. The Pitot tube is widely used in water supply systems, HVAC testing, and open‑channel flow studies.
v = sqrt{frac{2,(P_0 – P_s)}{rho}}
v = fluid velocity (m/s)
Parameters
Result
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Frequently Asked Questions
How does a Pitot tube measure fluid velocity?
A Pitot tube measures fluid velocity by capturing the difference between stagnation pressure (total pressure) and static pressure.
What is the formula for calculating velocity using a Pitot tube?
Velocity = sqrt(2 * (P0 - Ps) / rho), where P0 is stagnation pressure, Ps is static pressure, and rho is fluid density.
Why is Bernoulli's equation used in this calculation?
Bernoulli's equation relates the energy of a fluid at different points along its flow path, allowing for velocity calculations using pressure differences.
What are the units for stagnation and static pressures in this formula?
Stagnation and static pressures are typically measured in Pascals (Pa) or inches of water column (inH2O).
How accurate is a Pitot tube velocity measurement?
Accuracy depends on the calibration of the Pitot tube and the fluid's properties, generally within ±5% for clean, steady flows.
Can this method be used for compressible fluids?
This method is primarily for incompressible fluids. For compressible fluids, a different approach using Mach number and temperature is required.
What are some common applications of Pitot tubes?
Pitot tubes are commonly used in aerodynamics to measure airspeed, in HVAC systems to measure airflow velocity, and in fluid dynamics research.
Results are for informational purposes only and do not constitute professional advice.