- #36
Dieseltwitch
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In fact in a movie, i think it was air force one or something... they show an apu( aux power unit) that pops out with a turbine on it, when the aircraft has a loss of power for some reason.
Dieseltwitch said:In fact in a movie, i think it was air force one or something... they show an apu( aux power unit) that pops out with a turbine on it, when the aircraft has a loss of power for some reason.
If you do similar considerations, including car drag, transmission loss, and account for non-ideality of the rotor, you still actually end up with a wind car that could go faster than the free stream velocity in the upwind direction.
But I don't think such a car is built.
Sjonnie said:Such a car has been build at the Delft University of Technology. It worked. One of the important aerodynamic aspects of using wind energy is the LIFT principle. When a horizontal axis windturbine has wing-shaped rotorblades it will be able to rotate faster than the windspeed. This means a higher efficiency than drag-based windturbines.
However even with drag-based windturbines such a vehicle can be build. The drag of the vehicle should be minimized as much as possible. EXAMPLE: http://www.zeiltheorie.nl/wagentje.html
Roy Dale said:The air flowing around the car is not what is turning the turbine because there is no air flowing around the car unless the wind is blowing. Luckily aerodynamic force does not require air to actually flow around an object, it only requires a difference in velocity between the object and the sometimes still air (relative airflow). The relative airflow in this situation is caused by the linear motion of the object through the air as well as the motion of the object while in the air (rotation). This is important because to determine aerodynamic force you must first determine the direction of relative airflow that caused it.
Drag can spin any wind turbine but if this is a lift based horizontal axis wind turbine similar to a propeller, the same lift that causes it to spin can greatly (depending on its speed of spin) oppose its forward linear motion. The more the blades spin the more the relative airflow starts to change to a direction more opposite the direction of spin and subsequently the increasing lift starts to tilt more rearward opposit the direction of its linear motion.
Drag is not defined as the aerodynamic force that opposes forward motion. Oh wait a minute that’s the way it’s defined in aeronautic texts books, this may be the reason pilots do not know the difference between lift and drag.
It will not work no matter how you slice it. The turbine spins by the force of air flowing through it. The reactive force of the turbine pushes back on the air. This creates drag. your vehicle will need to work harder in proportion to how much extra drag is placed on it.irian said:I thought is good idea, because that is make like aeroplan, make you car have big power, less to use petrol, if you use wind turbine, that is make your car moving slow, in front your car have big drag force. like aero have big lift force to help plane to move to up but for renew energy you can try that, i have one e-book about wind turbine handbook, if you want to know you can download that in scribd.com. maybe the book can help you analyze factor and fabrication wind turbine.that is not econoical because you must add new compenet to connection wind energy with your car. thanks,
irian
ym : iriansyahputra
blog : http://irianpoo.blogspot.com/"
DaveC426913 said:It will not work no matter how you slice it. The turbine spins by the force of air flowing through it. The reactive force of the turbine pushes back on the air. This creates drag. your vehicle will need to work harder in proportion to how much extra drag is placed on it.
The only energy you will generate with the wind turbine is that which is generated by the engine working harder. What you've got there is a rather inefficient device that converts gasoline into electricity.
No, it doesn't happen like thatlightyears said:I say not to punch a hole in the car. I ask what if you take the surface that is resisting on the car and you take that resistence away to replace it with a turbine? That causes the same amount of resistence that it had orignally
The_Thinker said:If supposing we were to add a wind turbine connected to a generator to a moving car, would we be able to get the air flowing around the car to turn the turbine and therefore gain some energy? If it is possible, is it economical? if it is, is it practical? would there be a loss? would there be any gain in overall efficiency??
A friend of mine wants to do this project for collage and wants to implement this idea... I just want to know if it is practical or not...
So... what do you guys think?
Still no.OmCheeto said:If you slice a pickup truck into the equation it might work.
I think a bank of small turbines, placed behind and below the rear window of a pickup truck would both generate power and reduce the aerodynamic drag of the vehicle.
DaveC426913 said:Still no.
In order for the turbines to generate power, they must produce drag.
Adding wind turbines the the back end of a truck does not make it more streamlined, it makes it less streamlined (as was already said). Adding a turbine to anything makes it have more drag than it had before you added the turbine.OmCheeto said:True. But the design of trucks is so dreadfully bad in the first place, I can't imagine something streamlining the back end, not making the vehicle more efficient, even a bunch of mini-turbines.
dec2012omg said:I think it is definitely possible. One of us just needs to design it and show the formulas to prove it would be more fuel efficient. 'The energy is in the wind'
Welcome to PF. I'm not sure how to explain it any clearer than it already has. The wind moves a wind turbine by appying a force to it in the direction the wind is moving. In other words, for a wind turbine on top of the a car moving forward, the wind pushes it backwards -- slowing the car.dec2012omg said:I was thinking about this last night.
Surely a wind turbine on top of a car as it travels at speed would generate free energy.
Even if it only powers 20% of the car, this would be a great success for our planet.
I think it is definitely possible. One of us just needs to design it and show the formulas to prove it would be more fuel efficient. 'The energy is in the wind'
DaveC426913 said:Still no.
In order for the turbines to generate power, they must produce drag.
xxChrisxx said:Read the above.
If you take energy from something useful. You LOSE!
Ie it would be more energy efficient to simply use the electricity generated by the engine.
engine > altenator > phone
engine > motion > wind tubine > phone.
It adds more steps the energy has to take when ultimately it comes form the same source.
DaveC426913 said:pr0nChrispr0n
Momentum isn't energy.pronjay said:OK so the turbine causes drag, but you have the momentum of the car so maybe you would get a slight overall net gain of energy i.e. enough to power a mobile phone...?
Momentum isn't force either.yeah but you have the momentum of th vehicle so doesn't this more than counteract the drag?
Would cause back-pressure on the exhaust system.dr dodge said:hmmm..."turbine on the exhaust"...
You're expending energy getting the thing up to speed, then you're going to steal that energy for somewhere else?dr dodge said:what about perm magnets on the intake turbocharger rotor
OK, stick one on your roof then. If there's access to the grid (which is why there's a docking station there) then there's no point to attaching a wind turbine at the docking station. Attach it somewhere in the grid that's more efficient for function and just have wired into the grid.dr dodge said:given as much as most cars sit vs drive, the wind turbine would work good with a "docking station" for the hybred car
dr
Like a turbocharger...? Or you could use the turbine directly to power a generator.dr dodge said:hmmm..."turbine on the exhaust"...
Yes, but it is already an energy recovery device, so you probably don't gain any more by doing this.what about perm magnets on the intake turbocharger rotor
If you mean waste heat recovery then yes."antifreeze in the cooling system and waste exhaust"
Correct.big peltier device to change heat transfer to electricity
(from my understanding with an engineer here that worked with peltier devices they will produce electricity from temp transfer, although not as effieient as power into transfer heat)
Correct.given as much as most cars sit vs drive, the wind turbine would work good with a "docking station" for the hybred car
just not a good idea on the car at speed
dr
Yes, but the gain is greater than the loss. Turbochargers do, in fact, improve efficiency for a given power output.DaveC426913 said:Would cause back-pressure on the exhaust system.
A turbocharger is already an energy recovery device - he's just thinking of other ways to use it.You're expending energy getting the thing up to speed, then you're going to steal that energy for somewhere else?
You're not thinking critically. You're just pointing at components and asking if it's possible to tap energy from them.
DaveC426913 said:Would cause back-pressure on the exhaust system.