Wind Turbine Design

deccarroll85

As part of a 3rd year Mech Eng course we have been asked to design 3 parts of a 6kW wind turbine.
1: Bolts on the Tower base plate
2: Springs connecting the blade to rotor shaft
3: The rotor shaft
Would anyone have an idea of where to start with something like this?
Any guidance much appreciated....

Outkast_IRE

http://www.uaf.edu/acep/alaska-wind-diesel-applic/international-wind-diesel/presentations/WIDAC-Abbreviated-foundation-Coffman-Golder.pdf

This has some great photos of the steel foundation star and bolts. That might be worth a look at around pg 19 of it

mawk

you start with some knowns, some reasonable assumptions and some of the tools that you are learning in 3rd year mech.

take number 3.

you know the shaft has to transfer all the power and not break.
you know the electrical power is 6KW and since the turbine is not 100% efficient you know the shaft has to be speced higher than 6KW.

P=tw
6KW+efficiency loss=torque*Angular velocity

find out how fast a normal 6kw turbine spins. work out how much torque the shaft is designed to take nominally.

Then multiply that by factor of safety.

you now know how strong the shaft must be overall.

break out mohrs circle or do some mechanics of materials... pick a material and diameter of the shaft
BAM 1st class honour.

Thats what they want to see.

Shay_D_

Any ideas on where to start with the springs?

mawk

Yes. The rotors try to pull away like helicopter with it's nose down. Work out a rough magnetude of the lateral force by knowing their speed and surface area and profile and then use your mechanics of machines notes.

Pick a spring that fairly balances them forwards and back. Don't know for sure, but that sounds legit.

I don't (need to) remember the formulas for springs beyond hookes law but look them up and use them to imagine a spring diameter based on the properties of spring steel. Then specify that.

Also, fire up cad and draw it with dimensions. Got the little extra distance

paulmcgrath

I did my thesis on Wind Turbine's and i'm sure I have the answer to your question locked away up stairs somewhere.

But anytime i think about them brings me back to those dark thesis days. There never seemed to be an end in sight.

Does anyone else get sickened by big projects.

Ps what mawk said sounds about right

mawk

paulmcgrath wrote: »

I did my thesis on Wind Turbine's and i'm sure I have the answer to your question locked away up stairs somewhere.

But anytime i think about them brings me back to those dark thesis days. There never seemed to be an end in sight.

Does anyone else get sickened by big projects.

Ps what mawk said sounds about right

Thanks. oddly, I was trouble at reasoning from principles when I was in college. It somehow just clicked way later

paulmcgrath

had a think about this this morning.

do you have a cad model of your wt? if so, could be an idea to try run FE on it?

Shay_D_

No i just have a brief outlining the various details i need to find.

From brief;
Spring Design
The springs in question, help to connect the turbine blades to the main turbine nacelle. The purpose of the springs is to apply a force to the blade which counter balances a number of other forces which tend to fold the blade down into the axis of rotation of the turbine when the blades are rotating (so-called ‘coning’). However, when the wind speed reached a predetermined limit, the springs are not capable of preventing the blades from coning. This is the ‘overspeed’ control mechanism for the wind turbine. It is simple and effective mechanism and reduces complexity of the design relative to alternative control systems.

Some of the required deliverables for the spring design includes specification of such items as:
1. Spring Material
2. Number of springs required
3. Diameter of spring wire and of the spring(s)
4. Number of turns
5. Bend radii for the hook ends
6. Surface finish/treatment of the spring
7. Spring stiffness
8. Fatigue Factor of safety
9. Initial preload on spring (if any)
10. Any appropriate manufacturing tolerances.

mawk

Yup, that stuff is ask in your notes from sean f

Mr. Tezza

Back when I was in CIT first a few of the lads ther made a wind turbine, so I'm sure all the info necessary is lying around somewhere!