Wind Turbine Blade

If you copy an existing DESIGN what will you have designed?

Have you done any air foil design work? Any study on the subject? No?

Basic Design of Flying Wing Models

1. AeroFoil, A 2-d Airfoil Design And Analysis ProgramYou +1'd this publicly. Undo
2. Airfoil Design

Do your own homework!!

I am a mechanical engineering student. I know what constitutes in an airfoil. I want to know the specific airfoil for a turbine blade of length 50 cm - 80 cm. and I have to write down the lift co-efficient, the drag co-efficient and plot a graph. and then design the blade on pro-engineer software. So for designing a whole portable wind turbine, I got everything, the height, the shaft, the planetary gear system I am going to use and the magnetic generator and the battery to store the power. I will even have a bearing on which the the shaft conected to the rotor blades will be housed. I hope I am making some sense now. I want an airfoil shape that will work best for blades of small length. Is there any such airfoil data available?

"Is there any such airfoil data available?"

Probably. Where have you looked so far?

Do you really understand the purpose of these projects?

I'd think the goal would be for the student, you, to learn how to actually desgin something and validate the design. Then pick a design that you think is the best one AND GO WITH THAT ONE.

Good luck.

I have talked to my tutors. I am a mechanical engineering student and not an aerospace student. My main concern are the gears and the motors and the mechanism. the tutors asked me to get the airfoil shape online and then choose one based on a group of airfoil shape. I am not stealing. :)

I agree Lyn, do your homework; however, you failed to mention reynolds number...venturi pressure drops etc...

How about simply scaling it from an existing design?

How do you do that? Can you give a summary or some books to read? The issue with an existing design is that, the airfoil shape of the blade for the existing design have a limit of minimum length of 1 meter, and the airfoil blade i am designing is of length 50 cm - 80 cm. SO I hope you got my main concern now

Why bother with designing your own?

Just go on eBay and buy a set for $25 and be done with it.

My final year project is to create a portable wind turbine that can be carried anywhere and that will produce enough electricity to charge phones, light a camp, charge laptops. So it is a designing project only. I am going to have solar panels to increase the chances of gaining electricity. I know it sounds like an interesting project. So, you can know that building one is going to be quite expensive. I might buld one when I have enough cash and surely share with you the pictures. So can you suggest me an airfoil shape of the blade for a chord length of 50 cm to 80 cm. Having great lift :)

80 cm, produces around 30 watts or more for charging mostly 5

vdc devices , and is portable? I can make one for under $100 in a fair days work using almost entirely off the shelf components. No special airfoil designs required either.

I think you are greatly overestimating what it takes to make a simple but functional wind generator in that size and power range.

Well, Power = 0.5 x air density x Area of the rotor x (velocity)^3 if you input the power as 30 W air density as 1.22 area of rotor = Pi*r^2 Velocity of the wind on which you need 30 W = 10 km/hr or 25/9m/s and if you solve for the radius, you'll get a radius of 85.5 cm and that's the power absorbed from the wind by the blade and when you add gears to increase the rpm and use a magnetic generator. You will have an output power of 50 W. I hope now you got the whole deal :)

Yep I get it. I have been experimenting with wind power for over 20 years now and I can assure you that what the theoretical formulas say rarely ever performs that well in reality.

The biggest issue is realistic airfoil design. A highly efficient design for a specific size may get you 10 % more peak efficiency in the end over a basic design but the that added 10% may take 10x more skill, effort, and cost to manufacture placing its end cost to implement way past its added performance gains for capturing what it essentially a free energy source anyway.

Believe me I have been there and chased the numbers. Simple, basic, cheaper to build but runs at a slightly higher wind speed or larger diameter rotor always beats nit picky perfection in the end power production and longevity of the system as a whole.

BTW where do you plan on using these portable units that wont have someones head potentially in the way of a high speed blade?

The point is your design will need to have the lowest point of the blade preferably higher than 99% of the average population height which means needing a tower that is nearly 3 meters high to the center of your rotor which if you have done your wind loading calculations means you have a fair a mount of leverage forces to deal with and keep stable.

Especially so if this is going to be a light weight easily portable design which to me means it should be able to be broke down or set up in less than 5 minutes and fit in a common camping backpack sized carrying case weighing under 15 KG.

Wow this is hard to read!

You seem to be saying that for 30 watts (of wind power), you need 10 km/hr and a radius of 85.5 cm. So far so good.

But then you seem to be implying that adding gears and a generator will increase this to 50 Watts. That is, of course, completely wrong. The turbine itself might be 40% efficient. Adding gearing will reduce output power and the generator is not likely to be more than 90% efficient. 10 watts would be more reasonable, given otherwise perfect conditions.

You are not really thinking that increasing speed with a gearbox will increase power, are you?

Given that small of diameter of rotor there should not be any problem with running them as a direct drive setup well into the 1500 - 2500 RPM range thus eliminating the need for a gearbox all together.

Agreed.

I was pointing out the seemingly crazy physics implied by the OP's post: that the theoretical maximum wind power for the 10 km/h condition (30 Watts) would magically become 50 Watts at the output of the generator. In a near-perfect world, with perfect bearings, perfect blades and perfect generator, the best that could be attained would be the Betz number x the theoretical wind input, or a little under 18 Watts. In the real world, you can't come very close to even this.

It looks like the OP thinks over-unity machines are commonplace.

Oops. Did my math american style at 10 MPH not 10 KPH factoring for an at best 30 watt output not 50 watts.

Still I see no need for a gearbox on that small of rotor.

This must be homework, because the pragmatic solution is to buy a suitable blade set. Therefore, I recommend that you start by reading "Theory of Wing Sections" by Abbott and Doenhoff. This will give you the fundamentals for designing a section shape, and the book also provides experimental data from tests of many section shapes. You will discover the effects of scaling blades up and down.

eachairfoil section will have a specific angle of attack so as it could reduce stress and break down.

This is not the reason that each section has a specific angle of attack. Google "wind turbine blade twist."

the angle of attack is to reduce stress as well as for the lift, the velocity of air at each part of the airfoil will be different and the lift force will be different, for example , the root of the blade will have a much lower lift force than the tip of the blade and to attain that, we bring in the concept of angle of attack

Blade twist has very little to do with reducing stress, and a great deal to do with optimizing the L/D value at each station along the blade. At each station, the airfoil should be operating at that angle of attack which produces the best L/D figure, rather than (for instance) at that angle of attack which produces maximum lift (thus, wind turbine blades look like sailplane wings - long and slender, and devoid of high lift - and thus high drag - devices such as flaps and slats). Because the apparent wind angle is different at each station, the angle of attack must be different.

A blade in which the angle of attack (relative to the air stream) is the same at each station must be twisted (otherwise, the tip will operate at a higher angle of attack than the root, and will be stalled when the root is still flying). This aerodynamic requirement is then balanced with structural requirements.

The design of a blade is a compromise between structure and aerodynamics.

There is no single "best" airfoil section for a wind turbine, any more than there is a single best section for an airplane wing. Because your target windspeeds are low and your foil is relatively small, you will need to look for a section that performs well at low Reynolds numbers.

"the root of the blade will have a much lower lift force than the tip of the blade and to attain that, we bring in the concept of angle of attack"

"We" don't "bring in the concept of angle of attack" to attain the condition in which "the root of the blade will have much lower lift force". This condition is undesirable structurally. Structurally, it would be preferable to have more lift near the root so bending moments would be lower.

But the nature of a wind turbine has the tip flying at very high speeds and the root flying at very low speeds. This means that the tip can generate far higher lift (given that lift goes up with the square of velocity) than the root.

I gather English is your second language, but certainly your native language uses punctuation, capitalization, etc. to help clarify meaning, does it not? Your post would be clearer as several sentences.

Blades are so yesterday.....?

http://www.ecochunk.com/2196/2012/09/05/the-saphonian-blade-less-wind-turbine-costs-less-produces-more-energy/

That's a great concept, but mine is a portable wind turbine. Check this out.. http://www.youtube.com/watch?v=Z9o_6FH_Zns

This seems much less labor intensive...

http://www.oksolar.com/lion/Item/15646/solar-laptop-battery-charger-foldable-30-watts

or maybe something like this for on the go....

http://inhabitat.com/the-voltaic-fuse-10w-solar-laptop-charger-buckles-onto-any-backpack/

That's pretty cool :) I tried asking for the same while choosing my project, but the tutor ended up telling me that my project is supposed to be mechanical and solar is completely electronical. So i had to change my topic of project. By the way, are you having any idea about airfoil?

Maybe something vertical in design...?

http://www.ecochunk.com/1115/2012/07/19/prototype-vertical-axis-wind-turbine-and-be-flat-packed-and-shipped/

What about a bicycle with wind turbine wheels...? When you get to your destination you just tip the bike over and set the turbine blades....also could have it charge while pedaling....a dual system....

This is cool, mounts right on the bike....

http://mplsbikelove.com/forum/viewtopic.php?f=17&t=7242 (Sorry! Link no longer available.)

Dynohub....

"The Schmidt dynohubs put out 6v at 3w with no noticeable added resistance. The sexy look of a Schmidt installed on one's bike is way more bling than blight. I've got one on my touring bike that powers both my headlight and taillight. I've been meaning to look into designing a circuit to charge my cell phone, but I haven't gotten around to it yet."

http://www.peterwhitecycles.com/schmidt.asp (Sorry! Link no longer available.)

These are good...

http://shop.miniscience.com/navigation/detail.asp?id=BGEN1

$25. on Ebay....

http://www.ebay.com/sch/Wind-Generators-/121837/i.html?_nkw=blades&_frs=1

http://www.ebay.com/sch/Wind-Generators-/121837/i.html?_nkw=vertical+wind+turbine&_frs=1

http://www.onlinetes.com/wind-sail-type-vertical-axis-wind-turbines-111011.aspx