Mill wheel Diameter sizes

In summary, a millwheel will generate power based on the reduction in velocity or the change in height of the flow. The design will be based on the RPM and the volume and water speed of the stream.
  • #1
Aweir
1
0
Hi
Im thinking of constructing a millwheel with flat fins to run in a stream.
Is there a formula i can use to calculate the most efficient ∅ to construct it , when taking into account the velocity and area the stream and the surface area of the fins when submerged. and their relevant angles to the current.
It would be good to know the formula for converting the force generated to Watts.
Thanks!
 
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  • #2
The design will depend on the velocity of the stream and/or the hight difference available.
The energy available will be due to the reduction in velocity, or the change in height of the flow.

The diameter of the wheel will determine the RPM of the shaft. A small diameter, wide wheel will run faster than a large diameter narrow wheel. The diameter will therefore be chosen based on the RPM you require.
 
  • #3
You are lucky to have running water available. Could be a good project.
I don't know much about the details but I do know that 'over', rather than 'under' flow is the thing to go for in water wheel design. If you have enough drop and the possibility of building up any head of water (i.e. a mill-pond or reservoir), you will get much more Power out of your wheel if the water flows over the top of your wheel than under it.

If you have to have the wheel just dipping in the stream, you might consider a screw turbine design, which is, again more efficient than any paddle wheel (hence the way ships have been propelled for a century or more). No one uses paddle wheels for electric power on sailing boats - they all use screw turbines, these days, dragged behind, which is popular for ocean cruising.

The formula for force and power is, very basically
Power = Force times Speed
But, with a wheel, the speed varies over the radius so that formula doesn't say it all. You may be able to get 'anything' to rotate in flowing water but, to get the best out of it, you will need to do a fair bit of design prep.

Some idea of the scale you will be working on could help with useful answers. What sort of volume / water speed / depth and width of channel are you dealing with? You may find that a propellor from an old outboard motor would do very well.
 

1. What is the purpose of varying mill wheel diameter sizes?

The size of the mill wheel is important because it determines the speed and power of the mill. Smaller mill wheels are better suited for grinding finer grains, while larger mill wheels are better for grinding coarser grains or for generating more power.

2. How does the mill wheel diameter affect the output of the mill?

The diameter of the mill wheel directly affects the output of the mill. A larger diameter wheel will have a greater circumference, allowing for more grain to be ground in a single rotation. This results in a higher output of flour or other milled products.

3. Are there standard sizes for mill wheels or do they vary by mill?

There are no standard sizes for mill wheels, as they can vary depending on the type of mill and its intended use. However, there are commonly used sizes that have been developed over time for specific purposes, such as grinding wheat or corn.

4. How do you determine the appropriate mill wheel diameter for a specific mill?

The appropriate mill wheel diameter is determined by factors such as the type of grain being milled, the desired output, and the power source available. A miller may also take into account the size and capacity of the mill building when selecting a mill wheel diameter.

5. Can the mill wheel diameter be changed or adjusted?

In most cases, the mill wheel diameter cannot be easily changed or adjusted. It is typically determined by the design and construction of the mill. However, some mills may have adjustable mill wheel settings to allow for different grain sizes or power requirements.

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