Absolute Pressure of Fluid: Static + Dynamic = 15psi?

In summary, to determine the absolute pressure of a fluid, one must combine the static and dynamic pressures. However, the absolute pressure also depends on the ambient pressure, which can differ in various environments. In pipes with flow, the local pressure is determined by adding the differential pressure to the ambient pressure. In open columns of water, the pressure increases with depth. Additionally, there are different types of pressure, such as absolute and gage pressure, which are determined by subtracting the ambient pressure. Sealed loops have mechanisms to control pressure through temperature regulation or pressure valves.
  • #1
Idea04
194
1
to get the absolute pressure of a fluid you would take the static pressure and add it to the dynamic pressure. And you would have the total pressure. If that total pressure let's say 10psi static pressure and 5 psi dynamic pressure, gave a total of 15psi. So if you had 15 psi flowing through a pipe and into a closed tank to pressurize it would the value of the pressure in the closed tank be equal to 15psi the absolute pressure of the fluid?
 
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  • #2
The absolute pressure depends on the ambient pressure. In the Earth's atmosphere, at sea level, the ambient pressure is 1 atm or 14.696 psia. In a pipe, if there is flow, there is some pressure differential. If the outlet is at ambient pressure then one simply adds the differential pressure to ambient pressure to get local pressure.

If there is a column of water open at the top, the pressure at top is ambient and increases as depth increases.

One can talk of absolute pressure, or gage pressure, which is given by subtracting the ambient pressure from the absolute pressure.

Sealed loops usually contain an accumulator or 'pressurizer' with which to control pressure by regulating the temperature of the vapor phase, or pressure valves.
 
  • #3


Yes, the value of the pressure in the closed tank would be equal to 15psi, which is the absolute pressure of the fluid. This is because the absolute pressure is the total pressure of the fluid, which includes both the static and dynamic components. In this case, the total pressure of 15psi is made up of 10psi of static pressure and 5psi of dynamic pressure, resulting in the same value for the absolute pressure.
 

1. What is absolute pressure of fluid?

The absolute pressure of a fluid is the total pressure exerted by the fluid, including both the static pressure (due to the weight of the fluid) and the dynamic pressure (due to the fluid's motion).

2. How is absolute pressure of fluid measured?

Absolute pressure of fluid is typically measured using a pressure gauge or manometer. These devices measure the pressure exerted by the fluid, taking into account both the static and dynamic components.

3. What is the difference between absolute pressure and gauge pressure?

Absolute pressure includes the atmospheric pressure (or any other external pressure), while gauge pressure only measures the pressure above atmospheric pressure. Absolute pressure is always positive, while gauge pressure can be positive or negative.

4. What factors affect the absolute pressure of fluid?

The absolute pressure of fluid is affected by the density of the fluid, the height of the fluid column, the velocity of the fluid, and the external pressure. Changes in any of these factors will result in a change in the absolute pressure of the fluid.

5. Why is it important to consider both static and dynamic pressure when measuring absolute pressure of fluid?

Static pressure is important because it represents the weight of the fluid and can affect the stability of structures that contain the fluid. Dynamic pressure is important because it represents the pressure exerted by the fluid's motion and is often used in fluid dynamics calculations. Combining both static and dynamic pressure gives a more complete understanding of the total pressure exerted by the fluid.

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