Principle of Pitot Tube:
Based on Bernoulli's theorem. Measures the difference between the stagnation pressure and static pressure to determine fluid velocity.
Formula:
Where:
v = flow velocity
ΔP = difference between stagnation pressure and static pressure
ρ = fluid density
Construction:
Pitot Tube: L-shaped tube with an opening facing the flow.
Static Ports: Small holes on the side of the tube to measure static pressure.
Manometer: Measures the pressure difference between the stagnation and static pressures.
Working:
The fluid enters the tube, stagnating and creating a high-pressure region.
Static pressure is measured from the ports on the side.
The difference between the stagnation and static pressures is used to calculate the fluid velocity.
Uses:
Measuring the velocity of air in HVAC systems.
Used in aircraft to measure airspeed.
Applied in wind tunnel testing and river flow measurements.
Advantages:
Simple and inexpensive.
Can measure high-speed flows.
Minimal disturbance to the flow.
Disadvantages:
Accuracy can be affected by misalignment with the flow direction.
Limited to point measurement (not for varying velocity profiles).
Requires careful calibration and maintenance.