Funneling wind 2

[acadien]

I live in a area where the wind comes from the North-West most of the year. In winter (when the air is denser) the wind velocities are very high. So with this in mind I was thinking of building a funnel (5m X 5m entrance reduced to a 0.5m dia cylinder. Inside the cylinder ther would be a one or multiple stage turbine (static vanes and power vanes). I would like your comments on this and some usefull equations. I used Area1 * Speed1 = Area2 * Speed2, this gives me incredibly high velocities for the ratio previously detailled (higher than the speed of sound). Q1. Is the air density reduced as you funnel it? What do you think the efficiency (in %) of a turbine can be?

 

[buzzp]

Interesting idea. How long would the funnel be? Seems this number would have to be kind of high or the relationship you stated would not apply (if it does . But I am only a EE. Neat idea though.

 

[acadien]

Entrance to the Funnel would be 5m by 5m tapering at a 45deg angle to a conned turbine entrance having a 2inch (0.05m) exposure. The area of the turbine exposed to the wind is calculated by the equation pi*r^2. The outer radius minus the interior radius.
e.g wind 10m/s (36Km/hr)
A1V1=A2V2 -> 25sqrm*10m/s = (pi(0.25)^2-pi(0.2)^2)V2
V2 = 250/.07 = 3571m/s.

I am also an EE, I would like to use the electricity generated to electrolyse water and generate Hydrogen (this would be a later phase) Ph1 would be a grid tie-in to pay the bills for further expanssion, but 0.03$ per Kwh it takes a while.
Other concerns(scale 1 to 10): Snow and brime-5, turbulance-2, turbine parts-8, gearbox-8, generator-3, inverter-3, money-8.

 

[DFK]

You just can't expect the wind to go sailing into your throat area. Look at Bernouli's equation, which is an energy balance equation especially useful for fluid flow.
To simplify, the static pressure (SP) plus the velocity pressure (VP)at one point must equal the SP plus VP at the second point in the system. The practical implication is that should the velocity go up, the static pressure must go down.
The VP of the wind is expressed by .5 * (mass)(velocity)^2.
The static pressure in the throat can't be negative, so there is a limit on the velocity of the air in the throat. This is based on the upstream total pressure. For wind, this isn't much, compared to say, a wind tunnel, where there is a huge motor-driven fan or compressor.
This is fundamentally why you don't see much in the way of funnel's or concentrators in the wind turbine technology. You can't get something for nothing. Sorry.
In your comtemplated design, the throat would choke off flow. Since power is porportional to momentum flow (mass times velocity), you would get less power output with your funnel (due to losses) that you would putting your vanes out in the open.

 

[nbucska]

What about just use a big building with an open tunnel
in the middle ?

<nbucska@pcperipherals.com>

 

[acadien]

The Idea of a Wind Funnel is more to protect the turbine apparatus so it could be built on the ground. This has some advantages: lower cost for one. The disadvantage is obvious it's tuff to turn the entire thing into the wind. I got the idea by observing the snow drift in the winter. The wind comes uninterrupted from the bay for over 20 Miles and then it’s a 70foot or so cliff. Anyway it is from a mostly steady direction and is of high velocity. The funnel would also serve to allow less than centered wind to still power the turbine (at 60deg from center the useful wind drops to less than 5%).
I have started to learn about Bernoulli and his Physics in search of a ratio of mouth to throat area with acceptable air flow. Perhaps it is disappointingly only 1.1:1 or an interesting 10:1.
The second part of the Turbine (stator(s) and rotor(s)) is that for me it seems easier to build an aerodynamically “perfect” short blade (less than 12” for example) than a 15foot radius 3 bladed propeller, also easier to design. Of course the turbine would turn quite rapidly and one should plan accordingly. Any ideas on a name for the apparatus: FunWind: FunnelPower…
The Idea of a Wind Funnel is more to protect the turbine apparatus so it could be built on the ground. This has some advantages: lower cost for one. The disadvantage is obvious it's tuff to turn the entire thing into the wind. I got the idea by observing the snow drift in the winter. The wind comes uninterrupted from the bay for over 20 Miles and then it’s a 70foot or so cliff. Anyway it is from a mostly steady direction and is of high velocity. The funnel would also serve to allow less than centered wind to still power the turbine (at 60deg from center the useful wind drops to less than 5%).
I have started to learn about Bernoulli and his Physics in search of a ratio of mouth to throat area with acceptable air flow. Perhaps it is disappointingly only 1.1:1 or an interesting 10:1.
The second part of the Turbine (stator(s) and rotor(s)) is that for me it seems easier to build an aerodynamically “perfect” short blade (less than 12” for example) than a 15foot radius 3 bladed propeller, also easier to design. Of course the turbine would turn quite rapidly and one should plan accordingly. Any ideas on a name for the apparatus: FunWind: FunnelPower…

 

[jmw]

Re the last posting, mount the turbine vertically and use a weather vaned duct to face into the wind and re-direct the air flow downwards.
However, why is it easier to build a short bladed system where presumably the rotational speed will lead to serious balancing problems that to build a long bladed rotor? Folks have been building windmills for thousands of years with long blades, with shutters like a louvered door or with furling sails....and they can develop some very useful energy.

 

[xerxy]

Although the static pressure must go down when the wind is funneled and the velocity of the wind is increased, it should be noted that the pressure on the BACK of the funnel is DECREASED. It's the pressure difference of the front and back side of the funnel that will drive the turbine. Is that enough to make up for the losses in effiency? I'm not sure. I think it's worth looking into though.

The remarks on this have been very intelligent!

John

 

[acadien]

Thanks xerxy, I've started scavenging for parts on e-bay (permanent magnet, magnet wire, Diodes, voltage regulator IC, capacitors etc) and started building a small turbine. Working with magnets is interesting and lots of laught when they stick to your tools or you forget you have one in your hand... anyway. It's the windy season here and a good time for testing, my personnal R&D budjet is limited so it takes a littele time. The plan is to build a model that I can mount with and without a funnel and take measurements for analysis. Ultimately if this works I would build a bigger one. The long term goal would be to build a complete system generating 1000W for under 1000$US, this would be in my mind very competitive (I haven't done a market analysis yet) I will evnetualy as part of my general Parallele engineering philosophy. Also (my wife thinks I'm crazy for this) the licensing scheme for building the WindMill would follow the same philosophy as OpenSource Software. You shouldn't get billions of dollars because you were the fisrt personn to think of something (imagine if the first cave man who discovered fire, patented-it) anyway I talk a lot. Thanks for posting your comments.

 

[xerxy]

I'll be very interested to hear how your experiment goes Acadien. I've had a wind funnel design I've been playing with for several years. My design has always been at a very large scale. I just have a feeling the wind funnel needs to be at a fairly large scale to be very effective and efficient.

Let me know how your experiment goes. It will be a good learning experience no matter what.

john@johnhoward.net

Have a great day!

John

 

[235zzzo]

Hi ACADIEN

Please keep on being "crazy", but always doing something you believe on, even in the end, you just goy one more try,... until you get some solution. That´s for that we live in this planet, to do things for fun, as well.
Cheers!
zzzo

 

[235zzzo]

Hi, Xerxy!


What you said makes sense! The windfunnel technology needs flows with significant momentum in order to get good relation between flow momentum and the losses inside of the funnel. Besides that, you should to choose the rigth location and orientation for such ugly funnel...in some property of yours, of your father-in-law, maybe..
Cheers!
zzzo

 

[LarryXMM]

Hi Acadien, I was having similar ideas today as I was driving through some wide open MN farm country. Did you ever get any experimental results wrt/funnelling? I haven't really found anything conclusive ont the web as to why it should or shouldn't work. As you have said, it seems like the there would be significant advantages to a smaller fixed mount turbine.

Larry

 

[acadien]

Sorry LarryXMM no experimental results, I unfortunately lack the time ( I have 4 kids all less than 4) or the resources to build a model ( repeat the last brakets ). But I am still thinking about it especially tonight with a 70Km/h wind outside.... -15C with that.