What is the difference between nozzle (or a ventury) and flow control valve?

In summary, the main difference between nozzles and flow control valves is in the way they reduce the cross-sectional area of the pipe. Nozzles gradually reduce the area, converting potential energy to kinetic energy, while control valves do so abruptly. This results in a difference in the behavior of the fluid, with nozzles increasing velocity and reducing pressure, while control valves simply reduce the flow rate. For a better understanding of this concept, you can refer to books or other sources on fluid mechanics.
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In both the cases, the flow cross section area of the pipe is reduced.But in case of nozzles the velocity increases,pressure reduces and the flow rate is maintained.But in case of flow control valve, flow rate changes.(Assuming the fluid to be incompressible) Why is there a difference between the two cases?
 
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For any identical flow area and coefficient both the nozzle/orifice and the control valve act exactly in the same manner, reducing the size of the flow area in either case equally reduces the mass flow through the device.
 
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JBA said:
For any identical flow area and coefficient both the nozzle/orifice and the control valve act exactly in the same manner, reducing the size of the flow area in either case equally reduces the mass flow through the device.
Could you please explain how the flow area differs for the case of flow rate reduction from the case where velocity increases(flow rate maintained the same)?
Please suggest some books or other sources from which I can understand this.
 
  • #4
I may misunderstand your question, but:

A nozzle 'attempts' to preserve total energy by reducing cross-section gradually, with a minimum of friction/turbulence. Much of the potential energy due to pressure is converted to kinetic energy (velocity). Control valves reduce cross-section, but make no attempt to be gentle.
 
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  • #5
Dullard said:
I may misunderstand your question, but:

A nozzle 'attempts' to preserve total energy by reducing cross-section gradually, with a minimum of friction/turbulence. Much of the potential energy due to pressure is converted to kinetic energy (velocity). Control valves reduce cross-section, but make no attempt to be gentle.
Nice answer.So, in case of flow control valves, sudden reduction in cross sectional area is a reason for reduction in flow rate.
 

1. What is a nozzle and how is it different from a flow control valve?

A nozzle is a device used to control the direction and speed of a fluid, typically by creating a high-velocity jet. A flow control valve, on the other hand, is used to regulate the flow rate of a fluid by adjusting the size of the opening through which the fluid passes. Essentially, a nozzle controls the direction and speed of the fluid, while a flow control valve controls the flow rate.

2. How does a venturi differ from a flow control valve?

A venturi is a type of nozzle that uses a constriction in a pipe to create a high-velocity jet of fluid. This results in a decrease in pressure and an increase in velocity. A flow control valve, on the other hand, controls the flow rate of a fluid by adjusting the size of the opening. While a venturi also controls the flow rate, it does so by using a different mechanism.

3. Can a nozzle be used as a flow control valve?

In some cases, a nozzle can be used as a flow control valve by adjusting the size of the opening to control the flow rate. However, this is not the primary function of a nozzle, and a flow control valve is better suited for this purpose as it is designed specifically for flow rate regulation.

4. Which is more efficient, a nozzle or a flow control valve?

The efficiency of a nozzle or a flow control valve depends on the specific application. In some cases, a nozzle may be more efficient in controlling the direction and speed of a fluid, while a flow control valve may be more efficient in regulating the flow rate. It is important to consider the specific requirements of the application when determining which is more efficient.

5. Are nozzles and flow control valves used for the same purposes?

Nozzles and flow control valves are used for different purposes. Nozzles are primarily used to control the direction and speed of a fluid, while flow control valves are used to regulate the flow rate. They may be used together in a system to achieve a specific result, but their individual functions are distinct.

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