propeller for 50 to 60 mph wind

[airtime]

doing an experiment with a wind driven alternator behind a vehicle. the vehicle will be used to provide the exact wind speed. the blades will be inside a tube so wind will be coming from one direction only (and saftey) . trying to keep the tube to a 2o to 24" size. i'm thinking multiplal blades with a very high speed. trying to decide on a sutible size a/c 3 -phase alternator. this test will be for a battery charging system. i'm new to the wind power ideas and i'm no enginer (although my brother is and i will be referring the some technical questions to him so as not to get bogged down in technical stuff here). what i'm looking for is a starting point on the blade set up and alternator sizing. power out put predictions will be welcomed.

thanks in advance, gerald hocutt

[Projector]

No advice on this, but some encouragement.  It's easier to do something when you know it's been done before.  Smokey Yunick used something like this to gain an extra edge on the race track.  He had a generator powered by a propeller inside the engine bay of his race car to take the power generation load off the engine.  When it was discovered by track officials it was outlawed as a cheat.  This took place back in the 60s, and race track speeds were around 100-120MPH or so.  He used a simple small propeller for this, so with a more modern design aimed towards efficiency you might be able to make something of this at a lower speed.  Might also consider mounting this to the front of the car where it'll hit the wind head-on.  

If you can make enough power to not use the vehicle alternator, might be able to redesign it to mount the wind-spun alt inside the engine bay, and either eliminate the engine driven one altogether (would need a deep cycle battery to cover extended idling) and see a mileage savings on your car with this.  Do it right and you'd be able to do it without affecting the cd of your car.

[airtime]

thanks projector,

i'm hoping i can spin the thing fast enought to produce some serious power. like  a jet turbine, maybe wide blades to catch the air and really push the rpm's up. spin the alternator fast enough to pruduce some real power. looking at the 240 volt range.

[fungus]

Just remember that any power taken from the 'wind' that the car creates adds extra drag on the vehicle, making the engine have to work harder..

[airtime]

just trying to see how much power i can get out of this thing. not really taking in the vehicle. just using it for a halfway accurate wind measure. no wind tunnel around here open to the public.

how large an altinator do you think i could turn with this small a blade? as far as power goes.

[ghurd]

The vehicle will change the <air speed : speedometer> ratio.

A 1 MPH air speed to wind speed difference will throw the results into the "totally useless" region.

'Jerry' did tests about like this.  Might want to check his posts.

BTW, where is Jerry?

I hope his stuff is not deleted because he hasn't signed-on recently.

G-

[airtime]

ghurd,

are you saying that a car traveling 50 mph in zero wind condition would be different than a constant wind blowing 50 mph. not really concerned with the difference if there is one, just looking more into the rpm and speed of the propeller in regards to turning an alternator.

what is the normal pitch of a blade?   i was thinking 50 mph, at a 10 degree pitch would equal about 5280 rpms.

does this sound right?

just thru the 10 pitch out there because i don't know what it would really be.

[TomW]

G- ;

BTW, where is Jerry?

I hope his stuff is not deleted because he hasn't signed-on recently.



Nothing gets deleted due to absence.

Last I heard he had a fire at his audio store and maybe a death in the family? I suspect he still has his business email audiosourcesalem at aol dot com so might be worth sending an email to him if you want to get in touch?

Cheers.

TomW

[airtime]

i was looking at his post with the pole in the back of his truck. the power was getting up there when he stopped at 35 mph. plus he was using regular propeller blades.

i'm interested in upper 50 mph wind with solid looking water mill style blades, or jet turbine style blades, something that will catch the air and really spin.

[DanB]

I don't buy this one projector..

'Smokey Yunick used something like this to gain an extra edge on the race track.  He had a generator powered by a propeller inside the engine bay of his race car to take the power generation load off the engine.'

At best his 'wind turbine' under the hood was probably 30% efficient (at best - probably much worse actually).  the belt driven alternator/generator would've been better.

  'When it was discovered by track officials it was outlawed as a cheat.  This took place back in the 60s, and race track speeds were around 100-120MPH or so.  He used a simple small propeller for this, so with a more modern design aimed towards efficiency you might be able to make something of this at a lower speed.'

He was wasting power though...  he'd have done better to leave the belt on and not have a wind turbine there.  

  Might also consider mounting this to the front of the car where it'll hit the wind head-on.  

'If you can make enough power to not use the vehicle alternator, might be able to redesign it to mount the wind-spun alt inside the engine bay, and either eliminate the engine driven one altogether'

any energy captured by the wind turbine is also generated by the engine - it only makes for more conversions and lower efficiency to capture it with a wind turbine, much simpler and much more efficient to just use the engine itself and a belt.

 '(would need a deep cycle battery to cover extended idling) and see a mileage savings on your car with this.'

No matter how you do this you'd get worse milage assuming you generated the same amount of energy with the  wind machine as you did with the belt driven unit.

'  Do it right and you'd be able to do it without affecting the cd of your car.'

No....  Any energy you capture from wind created by driving a car will increase drag and it will not be terribly efficient.  If you could do this, and generate electricity without affecting the cd of the car (and Im not sure why you think thats possible) then you could have an electric that charged itself up as it went down the road and then you're talking perpetual motion.

Here is an amusing video on the topic!

http://youtube.com/watch?v=bkcn8ZkvKKc

[finnsawyer]

Two points:  A vehicle can cause turbulence in the air flow behind it, so you can't be sure what the speed of the air flow at the WT will be.  Better to place the WT some distance in front of the vehicle before the air flow is deflected.  Placing the turbine in a tube is not the same as having it completely in the free flow.  Check my Diary here:

   http://www.fieldlines.com/story/2007/12/5/16183/1323

to see where analyzing the case of a WT in a tube leads.  Get your brother to read it too.

[DanB]

Hi Gerald - what is the purpose of this?

If its to generate power with 'real' wind and the car is only for testing purposes then a 24" dia blade will not generate a great deal of energy.

If you're thinking of generating power for a car and this is to remain part of the car to make electricity 'for' the car then it makes no sense, you'd do much better to have another belt driven generator/alternator under the hood.

If you build something reasonably efficient then I expect you could have about 500 Watts @50 mph with a 24" blade(less than 1 hp) and I expect it would take about 3 - 4hp just to drive the aparatus down the road.

I say this stuff because It is a very common question we get in email - 'what if I put a wind turbine on my electric car...  so it charges itself up as it drives down the road'.  Oddly - the more 'conversions' involved the more people start getting confused and most weird perpetual motion/overunity schemes involve lots of conversions.  Again - it's impossible - you make more energy more efficiently by hooking your generator to your engine with a belt and there are still losses.

[Flux]

I can't see where this is going and I have no intention of getting very involved.

Dan is about right at 500W, I would have put your chances lower than that.

A true ducted windmill would no doubt do a little better but a windmill in a tube is not a ducted windmill and would likely perform a lot worse.

Wind speed is unlikely to be directly related to the vehicle speed in this case so it is not even a true calibration for a small machine.

Flux

[wooferhound]

it's been done before . . .

[airtime]

i was thinking, if you built an electric car from the ground up and do away with the common thinking of car building, you could design an electric vehicle that would be more effient. say by placing a large diameter tube in the middle of the car to house the turbines. that would leave room on either side of the tube to sit passengers and driver. the tube would be larger in the front and extend beyond or even with the front of the vehicle (look like a real ricer, lol) the larger air intake would then funnel down the tube and increase air flow to the turbine. if you say 500 watts would be max, then if the first turbine is putting out 500 watts, how mauch could i get out of the other 3 i would place inside the tube. 1500 to 2000 watts? this tube would extend thru the vehicle and exit in the rear. i would not expect this system to power the car just extend the range. charge the power pack some as your going down the road. i don't believeany electric car will function as well as it shouold if it's designed around a gas powered car. i'm no engineer and new to the electric power stuff so i'm just trying to get some feed back from more experienced people who hink outside the box.

[airtime]

after reading some on the links provided, i see there is great and highly technical debates on the down tube turbines effiency.. maybe it would be more effective to use the tube to catch the air and direct it to the rear of the car where it could branch off into 4 smaller tunnels to feed each turbine. like 4 20" diameter tubes each containing a turbine. the center channel could then be shaped into a different shape to maximize passenger room and still carry the air to the rear of the vehicle to power the turbines.

maybe even make the frame out of the 20"  tubes so each turbine would have it's own air flow, this would solve the airflow problem plus boost effiency on the other 3 turbines.the suspension would be connected to the tube frame, wheel electric motors provide the power.

might could place some smaller tubes on the roof to add some extra power. this could extend the range of the electric vehicles surely.

[DanB]

Yes, I was afraid that was where this was going... ;-)

Every bit of energy that the wind turbine captures in the car is generated by the electric motor that drives the car, and the conversion (electric motor to wheels to moving the car through the air to wind turbine blades to shaft to generator back to batteries etc...)is terribly inefficient.  the best you could hope for is to seriously reduce the cars range off its batteries by doing something like this.  (if you could increase it you'd have perpetual motion in the bag)

[elvin1949]

Dan

 This guy sounds like my baby brother.

He won't listen either.

later

Elvin

[airtime]

thanks for the video dan, that video car looked dangerous. i wonder how they turned out. it's a ruff design for sure but i bet they got some good data from the experiment.  

elvin, comments like yours kept the discovery that the earth was round from man for hundreds of years

 dan, for experimental purposes only, what type of propeller would you think would work best in capturing driving wind. a squirrel cage type, axis type or common wind turbine type.

on a squirrel cage type, it would only have to extend partially above the hood line and would cut the wind drag way down. just thinking here.

[DanB]

'thanks for the video dan, that video car looked dangerous. i wonder how they turned out. it's a ruff design for sure but i bet they got some good data from the experiment.  

elvin, comments like yours kept the discovery that the earth was round from man for hundreds of years'

I posted the video because it's funny...  it is rediculous.  Again - you can take an electric car and put a wind turbine on it and you will absolutely reduce the range - it's a silly thing to do.

 'dan, for experimental purposes only, what type of propeller would you think would work best in capturing driving wind. a squirrel cage type, axis type or common wind turbine type.'

No type.  A generator belted to the motor would be lots more efficient than a wind turbine on there and even that would be a really bad idea.

'on a squirrel cage type, it would only have to extend partially above the hood line and would cut the wind drag way down. just thinking here.'

I'd stop thinking about this right away and spend your time reading some basic physics.

[Projector]

Smokey's deeds are well documented on the internet.  Unfortunately I wasn't able to find the one that described the windmill driven generator, but I did read it.  Otherwise I'd not have posted it.  I'm not imaginative enough to make stuff like this up.

Airtime, I hate to say it, but now that I know your end goal I have to agree with the naysayers here.  I'm all for trying new things to improve efficiency whether people say they will work or not, but when you consider cost to benefit, I don't see how this would be worthwhile to pursue.  I doubt you'd be able to spin the generator fast enough to make the required power at speed.  Another problem, is the wind mass changes with speed.  With a fixed angle on the blades there is a fixed maximum efficiency you can achieve.  Some sort of variable blade pitch system would be needed to increase the effective range of the turbine.  

Good luck to you if you decide to pursue this, I hope you can make it work out but I don't think you will get very far.