Orifice plate effect on impeller flow rate

In summary, the conversation is about finding the flow rate through a pipe with an orifice plate under the pressure of an axial flow impeller. The person is seeking help and suggestions on how to calculate the new flow rate and find the pressure difference with the orifice plate. They also mention using a pump curve and reference a Wikipedia page and the Crane handbook for more information.
  • #1
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Hi everyone,

Hoping someone can point me in the right direction.

I'm trying to find (a theoretical approximation of) the flow rate through a pipe where the pressure is provided by an axial flow impeller, but restricted by an orifice plate.

I have (or can get hold of) all the physical parameters - pipe dimensions, motor power, impeller power number, impeller pressure drop, pumping capacity, orifice area, etc..).
I know the flow rate through the open pipe with no orifice plate.

I imagine placing an orifice plate over the open pipe will create a higher pressure, more drag, put more load on the motor and reduce the flow rate.

How will I find out the new flow rate?

I guess I need to somehow find the new pressure difference either side of the orifice plate. I don't know how to do this.

Any ideas/suggestions/equations/text book references would be a great help!

Thanks!
 
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  • #2
  • #3
Thanks for the link.
Unfortunately it's the pump I'm designing (not intended to be a pump, but has a pumpig effect).
I may need some experimentation to figure out my pressure drop. Thanks anyway :)
 
  • #4
I imagine placing an orifice plate over the open pipe will create a higher pressure, more drag, put more load on the motor and reduce the flow rate.


Actually most pump motors experience less load when flow is throttled.
When you were a kid did you put your hand over exhaust from Mom's vacuun cleaner and wonder why motor sped up? Vacuum cleaners are centrifugal, but this Wiki shows similar curve for axial..

http://en.wikipedia.org/wiki/File:Axial_1.png

Ther must be a way to get your pump curve. They've been designing them for well over century.

Are you familiar with Crane handbook, "Flow of Fluids"? Where i worked It was on every mechanical engineer's desk.
http://www.flowoffluids.com/publications/crane-tp-410.aspx
 
  • #5


Hello,

The presence of an orifice plate in a pipe can significantly affect the flow rate through an impeller. The orifice plate creates a restriction in the flow, causing an increase in pressure and a decrease in flow rate. The amount of restriction depends on the size of the orifice plate and the flow velocity through the pipe.

To calculate the new flow rate, you will need to use the Bernoulli's equation, which describes the relationship between pressure, velocity, and elevation in a fluid flow. By taking into account the pressure difference created by the orifice plate, you can determine the new flow rate through the pipe.

There are also several empirical equations that can be used to calculate the flow rate through an orifice plate, depending on the specific parameters of the system. I would suggest referring to a fluid mechanics textbook for more detailed information and equations.

In addition, it may be helpful to conduct experiments or simulations to validate your theoretical approximation and determine the exact flow rate through the pipe with the orifice plate. I hope this helps and good luck with your research!
 

1. What is an orifice plate?

An orifice plate is a thin metal plate with a hole in the center that is inserted into a pipe to measure the flow rate of a fluid passing through it.

2. How does an orifice plate affect the flow rate of an impeller?

The orifice plate creates a restriction in the pipe, causing a decrease in pressure and velocity of the fluid. This, in turn, affects the flow rate of the impeller by reducing the amount of fluid that can pass through it.

3. What factors influence the orifice plate effect on impeller flow rate?

The size and shape of the orifice plate, the size and speed of the impeller, and the properties of the fluid (such as viscosity and density) can all influence the effect of an orifice plate on impeller flow rate.

4. Is the orifice plate effect on impeller flow rate significant?

Yes, the orifice plate effect can be significant as it can cause a decrease in the flow rate of the impeller, which can have implications for the efficiency and performance of the system.

5. How can the orifice plate effect on impeller flow rate be minimized?

The orifice plate effect can be minimized by choosing an appropriate size and shape for the orifice plate, optimizing the impeller design, and selecting a fluid with properties that are compatible with the system.

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