Pitot Tube

Principle of Pitot Tube:

• Based on Bernoulli’s theorem. Measures the difference between the stagnation pressure and static pressure to determine fluid velocity.

Formula:

$v = \sqrt{\frac{2\Delta P}{\rho}}
$

• Where:
  • v = flow velocity
  • ΔP = difference between stagnation pressure and static pressure
  • ρ = fluid density

Construction of Pitot Tube:

1. Pitot Tube: L-shaped tube with an opening facing the flow.
2. Static Ports: Small holes on the side of the tube to measure static pressure.
3. Manometer: Measures the pressure difference between the stagnation and static pressures.

Working of Pitot Tube:

• 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.

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