I am missing the difference between “rotary design” and turbine?
Unless one is using different words according simply to the number of blades or their aspect ratio (chord, that is to say width, versus length.)
??
Rotation about the vertical axis is much more efficient at low altitudes.
See the link that Yo Momma posted.
I’ve worked on these in the past, but probably at a much bigger scale than what you are moving towards.
[quote]Vegita wrote:
That old fasioned rotary design looks like it could really grab some wind! I wonder why there isn’t many of them in use? What would be the downside?
Also Just thinking about an airfoil design, This may make the blade over time spin much faster than is possible from a regular balde. I think you would need sustained winds for this design to be effective though, And heavy blades would probably help to keep momentum up while winds temporarily die down or change directions.
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I am an architect. I actually work for the government on energy conservation projects. I have seen design similar to what you are proposing, they are installing them as micro generators on buildings. I wish I could find a website. This design works well on smaller scales for the reason it takes less torque to move the generator because the assembly is rotated as you mentioned. Once you get to larger scales the construction is unruly.
This is also a design used in fan boxes for large builing applications.
[quote]Bill Roberts wrote:
I am missing the difference between “rotary design” and turbine?
Unless one is using different words according simply to the number of blades or their aspect ratio (chord, that is to say width, versus length.)
??[/quote]
What I ment by that is blade shape. Essentially airfoil vs. angled flat surface or sail-like cloth.
[quote]BigJawnMize wrote:
Vegita wrote:
That old fasioned rotary design looks like it could really grab some wind! I wonder why there isn’t many of them in use? What would be the downside?
Also Just thinking about an airfoil design, This may make the blade over time spin much faster than is possible from a regular balde. I think you would need sustained winds for this design to be effective though, And heavy blades would probably help to keep momentum up while winds temporarily die down or change directions.
V
V
I am an architect. I actually work for the government on energy conservation projects. I have seen design similar to what you are proposing, they are installing them as micro generators on buildings. I wish I could find a website. This design works well on smaller scales for the reason it takes less torque to move the generator because the assembly is rotated as you mentioned. Once you get to larger scales the construction is unruly.
This is also a design used in fan boxes for large builing applications.[/quote]
Thanks, I am a bit of a science nerd so I am glad my instincts have at least some practical application. Small scale is precicely what I’m looking for. I could picture having say four of these things mounted on each corner of my house. They wouldn’t look too bad, almost like a decoration. I will have to educate myself on how to tie them into my home electical system. I was thinking if I tied them into the main circuit board, after running the electricity through the appropriate converter to make them AC 120V, that anything in the house using electricity would pull whatever they could off them, thus reducing the amount I am pullig from the grid. I’m not looking to do any selling back at this point, I am just interested in cutting my electric bill.
Maybye some day down the road I will look into more units and some type of power storage device or sellback to the utility. I would love to be able to in the future, generate enough electricity to heat and power my home, Charge an electric car or two and maybe still sell a little leftover back to the grid. But as Bob did, I need to take baby steps first, build one, test it, improve it, etc…
BBB, just because a specific design is in use, doesn’t mean it is the most efficient. It may be the most cost efficient in a specific region due to materials, regulations or other factors. I am really looking to build my own out of lightweight wood. I’m not at all experienced with metalworking, plastics will be an option too, but I think wood will look nicer and function similarly.
V
Vertical rotation.
Change your plane of thinking.
[quote]DoubleDuce wrote:
Bill Roberts wrote:
I am missing the difference between “rotary design” and turbine?
Unless one is using different words according simply to the number of blades or their aspect ratio (chord, that is to say width, versus length.)
??
What I ment by that is blade shape. Essentially airfoil vs. angled flat surface or sail-like cloth.[/quote]
As the purpose in either case is aerodynamic lift driving the rotation, wouldn’t the difference just then be between failure to optimize the airfoil shape (flat or sail-like) versus a more efficient shape?
[quote]Bill Roberts wrote:
DoubleDuce wrote:
Bill Roberts wrote:
I am missing the difference between “rotary design” and turbine?
Unless one is using different words according simply to the number of blades or their aspect ratio (chord, that is to say width, versus length.)
??
What I ment by that is blade shape. Essentially airfoil vs. angled flat surface or sail-like cloth.
As the purpose in either case is aerodynamic lift driving the rotation, wouldn’t the difference just then be between failure to optimize the airfoil shape (flat or sail-like) versus a more efficient shape?[/quote]
Not exactly, they function on 2 different principals to create a resultant thrust. Modern turbines have blades that work at least primarily on Bernoulli?s principle where velocity difference on either side of the foil creates a pressure difference causing a perpendicular force to the flow of air.
The older style windmills work off conservation of momentum. Essentially they deflect flowing air to the side causing a reaction force in the blade. Like you take a ramp on a slick surface and let a block slide down the ramp. The ramp will slide in the opposite direction of the block.
To my understanding, the ramp idea works better at slower wind and rotational speeds (essentially its more ?torque-e?). They are however very limited in rotational speed and by turbulence problems.
Work however is force * distance (torque * angular distance in rotation), and modern turbines do this much better.
I can’t agree: f=ma in either case.
It’s just that one is lousy aerodynamics – like an airplane with a flat plank for a wing – and the other is better aerodynamics.
[quote]Vegita wrote:
I will have to educate myself on how to tie them into my home electical system. I was thinking if I tied them into the main circuit board, after running the electricity through the appropriate converter to make them AC 120V, that anything in the house using electricity would pull whatever they could off them, thus reducing the amount I am pullig from the grid.[/quote]
Yes, you will need to research this further. Unfortunately it’s not that simple and what you are proposing here would be very dangerous.
Why not set a simpler goal, such as charging a battery system that will be used to power a given light or set of lights that you have wired to dedicated DC.
Don’t let Snowball destroy it.
[quote]Bill Roberts wrote:
I can’t agree: f=ma in either case.
It’s just that one is lousy aerodynamics – like an airplane with a flat plank for a wing – and the other is better aerodynamics.[/quote]
One is lousy aerodynamics on purpouse. Think of the flat rotor blades like a sail, they want to catch the wind and effectively Tack into it. You are not trying to create pressure differences on one side of the blade from the other, as you are in an airfoil design. You are simply trying to catch the wind energy against a surface, and send the wind one way, and the surface goes the other way.
V
[quote]Yo Momma wrote:
Vertical rotation.
Change your plane of thinking.
[/quote]
I just can’t see how this thing is supposed to spin. I have seen other vertical designs, the only problem I see with those is it would be much harder to make mostly out of wood. I would need to learn some metalworking and welding at a minimum to make one of the more complex designs. Here are a few I have come across before.
Here is another one.
V
[quote]Bill Roberts wrote:
Why not set a simpler goal, such as charging a battery system that will be used to power a given light or set of lights that you have wired to dedicated DC.[/quote]
This is the way to go. Tie the windmills into a bank of deep cycle batteries. Connect these to an invertter connected to your fuse box. Remember it will take a massive turbine to generate power that you can use in real time, for example 1KW will power a 100watt light bulb for 10hrs, the power needs of even a toaster or small appliance will overwhelm most small turbines. With the batteries, you charge them and then you can draw from them at relatively high rate for good period of time when needed. Deep cycle batteries can discharge 80% or more of their capacity without being damaged. This setup will also smooth out the current supplied to the house (no ups and downs).
[quote]totalfit wrote:
Bill Roberts wrote:
Why not set a simpler goal, such as charging a battery system that will be used to power a given light or set of lights that you have wired to dedicated DC.
This is the way to go. Tie the windmills into a bank of deep cycle batteries. Connect these to an invertter connected to your fuse box. Remember it will take a massive turbine to generate power that you can use in real time, for example 1KW will power a 100watt light bulb for 10hrs, the power needs of even a toaster or small appliance will overwhelm most small turbines. With the batteries, you charge them and then you can draw from them at relatively high rate for good period of time when needed. Deep cycle batteries can discharge 80% or more of their capacity without being damaged. This setup will also smooth out the current supplied to the house (no ups and downs). [/quote]
A Massive turbine, or possibly many small ones. I do like the deep cycle battery idea also, It just means more used space and more up front investment, I don’t think the batteries would be very cheap. As battery technology get better and better, this will be a good way to go.
V
Perhaps your current horizontal design can be modified to enhance performance by the addition of a partial duct sail, like this picture. This would have to be mounted at the edge of your rooftop, so the sail will deflect vertical wind flow.
your makeing it more complecated than it needs to be, if your building it yourself why not go for an established design, like the kite generator. Get a cheap kite, wrap the cord around a dynamo, launch the kite… easy.