Cavitation and decrease in pressure confusion

In summary, cavitation is the formation and collapse of vapor bubbles in a liquid due to a decrease in pressure. It can cause damage to equipment and affect its performance. It is caused by high fluid velocity, low pressure, and high temperature, and can be prevented by reducing fluid velocity, increasing pressure, and selecting a suitable liquid. Cavitation can have negative effects on equipment, such as erosion, reduced efficiency, and noise and vibration.
  • #1
R Power
271
0
I am confused a bit about fact that there is a decrease in pressure as velocity is increased which is the principle behind cavitation. Now cavitation occurs when velocity of liquid increases so much that pressure decreases (as according to bernoullis equation) and reaches below it's vapour pressure and boiling starts.
Now my confusion is that why would pressure fall down? To increase the velocity of liquid we have to increase the pressure on the other side or we have to force the liquid we can say which will increase fluid pressure at that position. Due to this a large pressure difference will be set up and fluid will flow with high speed but this pressure difference is due to increase in pressure on the other side and not due to decrease in pressure where cavitation would occur.
Why would cavitation occur then? There should be no decrease in pressure , only difference between pressures would be more . so why cavitation occurs.
 
Physics news on Phys.org
  • #2

Thank you for your question about the principle behind cavitation. Cavitation occurs when the pressure of a liquid drops below its vapor pressure, causing the liquid to boil and form vapor bubbles. This decrease in pressure can be caused by an increase in velocity, as described by Bernoulli's equation.

To understand why this decrease in pressure occurs, we must first understand the concept of flow energy. When a fluid is in motion, it has kinetic energy and potential energy. Kinetic energy is the energy associated with the motion of the fluid, while potential energy is the energy associated with the position of the fluid.

When the velocity of a fluid increases, its kinetic energy also increases. This increase in kinetic energy comes at the expense of potential energy, meaning that the fluid's pressure decreases. This is because the fluid particles are moving faster, and therefore have less time to interact with each other, resulting in a decrease in pressure.

Now, let's apply this concept to cavitation. As the velocity of a liquid increases, its pressure decreases. If the pressure drops below the vapor pressure, the liquid will start to boil and form vapor bubbles. These bubbles then collapse, creating shock waves that can cause damage to equipment.

To prevent cavitation, we can either decrease the velocity of the liquid or increase the pressure on the other side. However, simply increasing the pressure on the other side will not necessarily prevent cavitation. This is because the pressure drop is a result of the fluid's energy, not just the difference in pressure between two points.

In summary, cavitation occurs when the pressure of a liquid drops below its vapor pressure, which can be caused by an increase in velocity. This decrease in pressure is a result of the fluid's energy, and not just the difference in pressure between two points. I hope this explanation helps to clear up your confusion.
 

1. What is cavitation?

Cavitation is the formation and collapse of vapor bubbles in a liquid due to a decrease in pressure. This can occur in various systems, such as pumps, propellers, and turbines, and can cause damage to the equipment and affect its performance.

2. How does cavitation affect pressure?

Cavitation causes a decrease in pressure due to the formation of vapor bubbles. As these bubbles collapse, they create shock waves that can damage the surrounding material and decrease the pressure in the system.

3. What causes cavitation?

Cavitation can be caused by various factors, including high fluid velocity, low pressure, and high temperature. It is also influenced by the properties of the liquid, such as its viscosity and surface tension.

4. How can cavitation be prevented?

Cavitation can be prevented by reducing the fluid velocity, increasing the pressure, and selecting a liquid with suitable properties for the system. Proper maintenance and design of equipment can also help prevent cavitation.

5. What are the effects of cavitation on equipment?

Cavitation can cause erosion or pitting on the surface of equipment, leading to reduced efficiency and performance. It can also create noise and vibration, which can be damaging to the equipment and may require costly repairs.

Similar threads

  • Mechanics
Replies
5
Views
1K
Replies
12
Views
12K
Replies
26
Views
1K
Replies
2
Views
1K
  • Mechanics
2
Replies
43
Views
4K
Replies
4
Views
2K
Replies
3
Views
988
Replies
48
Views
4K
  • Thermodynamics
Replies
7
Views
735
Back
Top