Mechanical enery equation to valve equation

In summary, the conversation discusses a request for help in deriving the algebraic link between the mechanical energy-equation and the valve equation in the context of a bachelor thesis on valves. The valve equation is also referred to as the flow coefficient-equation and is expressed as Cv=Q * [Square](Sg/[Delta]p). It is suggested to derive it from Bernoulli's equation and consider neglecting elevation and assuming constant velocity. The conversation also mentions the need for field units (American units) and expresses appreciation for any help.
  • #1
Fingon
1
0
Hi

I’m writing my bachelor thesis about valves, and was wondering if anyone could help me with the following derivation:
I need to show the algebraic link between the mechanical energy-equation and the ”valve equation” that is Cv=Q * [Square](Sg/[Delta]p). This can also be called the flow coefficient-equation.

Everything in field units (american units)

All help will be appreciated a lot!
 
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  • #2
Fingon said:
Hi

I’m writing my bachelor thesis about valves, and was wondering if anyone could help me with the following derivation:
I need to show the algebraic link between the mechanical energy-equation and the ”valve equation” that is Cv=Q * [Square](Sg/[Delta]p). This can also be called the flow coefficient-equation.

Everything in field units (american units)

All help will be appreciated a lot!
Pressure is energy / unit volume so the [itex]\Delta P = Q^2\rho/C_v[/itex] expresses an energy loss per unit volume.

AM
 
  • #3
Derive it from Bernoulli's. As the length of the valve is generally too small, you can neglect difference in elevation (if any) and also it is a safe assumption to consider constant velocity. The pressure drop across the valve then becomes a function of velocity. Express frictional resistance in terms of velocity and equate it to pressure drop.
 

1. What is the mechanical energy equation to valve equation?

The mechanical energy equation to valve equation is a mathematical formula that relates the mechanical energy of a system to the flow of fluid through a valve. It is commonly used in fluid mechanics and thermodynamics to calculate the work done by a fluid as it passes through a valve.

2. How is the mechanical energy equation to valve equation derived?

The mechanical energy equation to valve equation is derived from the principle of conservation of energy, which states that energy cannot be created or destroyed, only transferred or converted into different forms. It takes into account the potential energy, kinetic energy, and flow energy of a fluid as it passes through a valve.

3. What are the variables in the mechanical energy equation to valve equation?

The variables in the mechanical energy equation to valve equation include the fluid density, velocity, and pressure at the inlet and outlet of the valve, as well as the height and velocity of the fluid above the valve. These variables can be measured or calculated to determine the energy transfer through the valve.

4. How is the mechanical energy equation to valve equation used in real-world applications?

The mechanical energy equation to valve equation is commonly used in the design and analysis of fluid systems, such as pipelines, pumps, and turbines. It allows engineers to calculate the energy losses and efficiency of these systems and make improvements to optimize their performance.

5. Are there any limitations to the mechanical energy equation to valve equation?

The mechanical energy equation to valve equation assumes that the fluid is incompressible and that there are no energy losses due to friction or turbulence. These assumptions may not hold true in all real-world situations, so it is important to use the equation with caution and consider other factors that may affect the performance of the system.

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