Measure velocity and flow rate using pressure differences.
A Pitot tube measures stagnation pressure; with static pressure it gives velocity V=√(2ΔP/ρ). A Venturi meter measures flow through a throat via pressure drop: Q=C_dA₂√(2ΔP/(ρ(1-β⁴))). Orifice plates and rotameters are alternatives.
A 100 Pa dynamic pressure of air indicates 12.9 m/s.
Pitot tubes and Venturi meters measure flow speed or rate from pressure differences, which are simple and reliable for water, air and gases.
Measure velocity and flow rate using pressure differences.
Pitot tubes and Venturi meters measure flow speed or rate from pressure differences, which are simple and reliable for water, air and gases.
A contraction increases velocity and lowers pressure, and the pressure difference gives the flow rate through Bernoulli and continuity.
The stagnation pressure, and the difference from static pressure gives the dynamic pressure and the flow speed.
Typical applications include measuring the airspeed of an aircraft with a pitot tube, metering water flow in a municipal pipe with a venturi and checking air velocity in a duct with a pitot traverse.
Study "Bernoulli equation" first (topic 53 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
Discharge coefficient C_d≈0.98. Permanent pressure loss. Aircraft airspeed indicators.
A 100 Pa dynamic pressure of air indicates 12.9 m/s.
The next topic is "Momentum equation", which builds directly on this one.
It is classed as Intermediate in Thermodynamics & Fluids (topic 54 of 105). It is an intermediate topic. Work through the beginner topics in Thermodynamics & Fluids first.
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