Bernoulli's Equation and tube vacuum

In summary, the conversation discusses the use of a venturi tube and a secondary opening to create a local vacuum. The question is whether a different equation should be used to calculate the rate of air induction or if Bernoulli's equation for pressure drop still applies. It is suggested that the Bernoulli equation can be applied if the vacuum is not too large and a discharge coefficient should be used for the non-ideal flow through the air hole.
  • #1
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I have a venturi tube and downstream of it, there is a small secondary opening at the end of the throat. This is where the local vacuum is created as the velocity increases and the pressure decreases. This difference between this pressure and the atmospheric pressure will induce air into the secondary opening. Does anybody know if I have to use another equation for the rate of air induction versus this differential pressure or will the same Bernoulli's equation for pressure drop through the venturi tube still apply? If there is another equation, do you know what it is? Thanks!
 
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  • #2
If your vacuum is not too large (say 13.2 psia), you could apply the Bernoulli equation to this "air hole" also. You should use a discharge coefficient for the air hole since flow will not be ideal.
 

1. What is Bernoulli's Equation?

Bernoulli's Equation is a fundamental equation in fluid dynamics that describes the relationship between fluid pressure, velocity, and elevation. It states that as the velocity of a fluid increases, its pressure decreases, and vice versa.

2. How is Bernoulli's Equation applied in real-life situations?

Bernoulli's Equation is used in a variety of real-life situations, such as in the design of aircraft wings, in calculating the flow of water through pipes, and in understanding the dynamics of airflow in ventilation systems.

3. What is the significance of tube vacuum in Bernoulli's Equation?

In Bernoulli's Equation, the term for pressure includes both the fluid's static pressure and the dynamic pressure caused by the fluid's velocity. In a tube vacuum, the fluid's velocity is zero, so the dynamic pressure is also zero, simplifying the equation and allowing for easier calculations.

4. How does tube vacuum affect the flow of a fluid?

In a tube vacuum, the fluid will flow faster due to the absence of air resistance. This increase in velocity decreases the fluid's pressure, according to Bernoulli's Equation. This effect is often demonstrated in experiments where a fluid is sucked through a straw.

5. Can Bernoulli's Equation be used to explain the lift force on an airplane wing?

Yes, Bernoulli's Equation is one of the principles that explains the lift force on an airplane wing. As the air flows over the curved surface of the wing, it must travel faster than the air below the wing, creating a difference in pressure that results in lift.

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