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AeroDynamic Drag, why fight it? Use it

Discussion in 'Future Cars' started by clark, Oct 28, 2015.

  1. clark

    clark New Member

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    The Energy recuperate rate from the regen is around 64% maxed, i have read. And then there is energy lost through friction and Aerodynamic drag.


    I am just wondering if people has tried not to reduce aerodynamic drag but to calculate where the aerodynamic drag is the greatest.... or where the grill is and use micro wind turbine to recuperate the energy lost through wind drag etc.

    With micro wind turbine within the grill, it allows the flexibility to have different designs and not be greatly impacted by energy lost through drag. Also covering all windows with UV transparent solar panel might further reduce the energy lost for heating and filling in the energy lost from the road-tire friction....

    Just a thought

    - - - Updated - - -

    I was just randomly wondering about that, because Drag is correlated with the increase of speed,area, and also the energy lost/usage/recuperate rate. Thats all........

    Was just wondering what if the grill is as large as a mustang, then you stick 5 or so micro wind turbines in......how much energy can be outputted with it.....
     
  2. Johan

    Johan Took a TSLA bear test. Came back negative.

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    If you put turbines anywhere the drag will definitely increase as a result, and the amount of energy generated will certainly be much lower than what's lost due to the increase in drag, since no system (and certainly not a mini wind turbine) has 100% efficiency.

    I don't want to be belittling but please think of what you're proposing... Free energy anyone?
     
  3. wdolson

    wdolson Active Member

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    With any kind of energy transfer, there are always losses. What goes into the system is never as much as you get out. It's why perpetual motion machines are believed to be impossible.

    If you opened up the front of the car and put wind powered generators in there, the energy you get out of it will never be as much as you lose from the increased drag from opening up the front. Wind, hydro, and solar power works because we are tapping energy that would have hit that spot anyway. The energy is already there in the environment and we're just harvesting it. Now if you have a wind turbine on your car and it was a particularly windy day, you might be able to get some small energy gain, but even then the gain would be a lot less than from a stationary windmill because you're paying energy to move the windmill, both weight and drag with the car. It's far more efficient to make the car as efficient as possible and generate the power to drive it from stationary sources.

    Unfortunately with this sort of thing the saying "there ain't no such thing as a free lunch" comes into play.
     
  4. AlexT

    AlexT Member

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  5. TheTalkingMule

    TheTalkingMule Active Member

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    Obviously that's true, but what about in applications where you are just "trimming some of the fat"? I'm a 2001 Wrangler owner for instance and would like my next vehicle to be a Model 3 followed a few years later by a Tesla/Jeep effort at recreating a pure EV Wrangler TJ with an integrated field deployable solar array.

    The problem with Jeeps is they are a rolling cube, least efficient vehicle body know to man. Would there be a way to channel some of the air smacking the abrupt front of the vehicle into some kind of internal central wind tunnel with mini turbines? Is there no scenario where this makes sense? Wouldn't you be able to find a setup where the net drag is the same, but you get a small amount of charge out of the equation?

    Realizing of course this is infeasible on a vehicle like the Model S where the drag is optimized for efficiency.
     
  6. mmccord

    mmccord Member

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    You'd be better off doing the same thing without the turbines. (ie, just make it more aerodynamic to begin with)
     
  7. green1

    green1 Active Member

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    Unless the turbines are providing you with some other benefit (you really really love the turbine look?) you'll always do better letting the air flow instead of putting a turbine in the way. That could be either a tunnel through the vehicle, or on the outside of the vehicle, in either case, the lack of the turbine will always beat having it assuming everything else stays the same.

    So yes, a wall with a turbine in it will be more efficient moving through the air than a wall without one. But a wall with a turbine sized hole in it will be far more efficient than both.
     
  8. wdolson

    wdolson Active Member

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    However if you have a turbine in there, you need to supply energy to run the turbine, which comes from the battery pack. Basically you can't beat aerodynamic drag. City BEVs can be rolling cubes because drag is not a big factor in their efficiency, but any BEV designed for highway use is probably going to be as aerodynamic as possible until battery energy density gets to a point where the range hit from drag is unimportant. For example if you had a batter pack that could get a Model S 1000 miles range (under real world condition), but it would only be 800 miles range if put into a vehicle the shape of a Jeep, most buyers wouldn't worry about the extra 25% range they could get with the Model S shape because they are rarely going to drive even 800 miles in one go anyway.

    To some extent that is what we have in the ICE world. Gasoline has so much energy density (33X a gallon volume over Li-Ion cells) that people live with the range hit on poor aerodynamic vehicles. Additionally the shape of the efficiency curves for ICEs is more spread out than for electric motors. Drag is a bigger hit on efficiency for BEVs than ICE, but the trade off is the ICE is far less efficient overall (about 1/3 to 1/4 the efficiency).
     
  9. green1

    green1 Active Member

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    I think you're giving the ICEs too much credit, last I heard it was more like 1/5th
    I love telling people my car has the equivalent of about a 3 gallon gas tank, but I can drive 250 miles on it. oh, and it could seat 7...
     
  10. Drewflux

    Drewflux Member

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    Unfortunately a solar panel fitted to the vehicle would not generate enough power to charge the battery. It would be interesting if Tesla were to go down the route Toyota did with the prius. Fit a solar panel to the roof, use it to allow preconditioning of the climate control. However I would also use it to maintain the 12v battery.
     
  11. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Unless it's changed, all the solar panel on the Prius does is run a ventilating fan.
     
  12. windgrins

    windgrins Member

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    Directly (UP and Down)wind Faster than the Wind.

    Just to be clear, the DUWFTTW video referenced is very real. There is no perpetual motion involved or violation of the law of conservation of energy as many think. The same machine can run Directly Downwind Faster than the Wind also (with a slightly different gearing and propeller configuration).

    DDW.mov - YouTube

    The reason this is completely different from the initial proposal for the thread is that the vehicle in the video is capturing wind energy not created by the vehicle itself but is from the air moving over the ground. For it to work there has to be an actual motion of air with respect to the surface AKA "wind". (it doesn't matter if the surface is moving or the air is moving as long as there is relative motion). The vehicle captures energy by slowing the air motion with respect to the ground through a tricky linkage of the propeller to the wheels. I will most definitely assure you that this vehicle is very real and holds the world records for travelling directly up and downwind faster than the wind itself that is powering it. And I will repeat again that it is neither Perpetual Motion or something from nothing. The energy is supplied by the wind and it will slow to a stop if the wind isn't blowing over the ground.

    The Chief project scientist is Rick Cavallaro who holds a Masters degree in Aerospace Engineering. It is interesting because it is very counterintuitive for most folks. Everyone always asks the same question: "How can you possibly run faster (downwind) than the wind which is powering you since you have to pass through the point where the relative wind on the vehicle is zero?". The answer is because of the way the vehicle harvests energy with the wheels and propeller due to the relative motion of the air and ground (not as is usually thought, the vehicle and the air).
     
  13. Johan

    Johan Took a TSLA bear test. Came back negative.

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    Thanks for the video. Cool stuff. Either I must be very dumb or very smart, because to me there's nothing counter intuitive to the car (being very light and efficient) going against the wind faster than the wind itself, powered by the windmill. In fact it's easier for me to imagine how this could be done (mechanically) than how a windmill would make a light bulb glow, for example (seems like a more complicated apparatus to me).
     
  14. green1

    green1 Active Member

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    Thing is, when there is not wind, or when you are trying to travel faster than this device can manage, it is now additional weight, and (significant) additional drag on the vehicle.

    It's a neat device, but it doesn't give you any advantage (and in fact is a significant disadvantage) in normal real world applications.

    It's a similar idea to old sailing ships, they could sail on certain points of sail faster than the wind itself, but they were replaced by motorized vessels because the motorized vessel could travel even faster, and weren't at the whim of the wind.
     
  15. Model 3

    Model 3 Active Member

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  16. Johan

    Johan Took a TSLA bear test. Came back negative.

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  17. Model 3

    Model 3 Active Member

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    I don't know anything more then what's in that article. Maybe he parks the car against the wind?

    I think I'm probably been Nigeria-scammed ;)
     
  18. wdolson

    wdolson Active Member

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    This article has more pictures of the car:
    http://www.oaupeeps.com/2014/07/archive-oyeyiola-segun-student-of-oau.html

    It smells of a perpetual motion kind of scam to me. Looking at the pictures, there are no inlets for the air to enter for the wind turbines. And if they were there, on a windless day, or if not driving into the wind, the drag from the air going through the turbines would be more of an energy loss than you would gain from the electricity produced. You would have to drive into a pretty hefty headwind to overcome the losses and actually get any benefit, and it would be unlikely with such a poor aerodynamic shape as that thing with a big wing on the roof.

    Looking at the pictures, he's either done a very good job of tucking the wiring for the solar panel away, or that thing is not connected to the car. Considering his other claims about the wind turbines, I wouldn't be surprised if the solar panel isn't connected to anything.
     
  19. Johan

    Johan Took a TSLA bear test. Came back negative.

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    "Hello Sir! My name is Oyeyiola Segun, a Part 5 student of the Electronic and Electrical Department of Obafemi Awolowo University, Nigeria.

    I was well informed of your stronghold in business and foresight in investing in renewable power transportation over the years, an incentive that induced me writing you to seek your ability at sustaining the conclusion of a pending transaction for our mutual benefit..."
     
  20. Model 3

    Model 3 Active Member

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    According to one on an another forum a commenter on the article (I can't see the comments at all my self) was irritated that the article forgot to tell that the wind turbine was in the "frunk" and was put up to use when the car was parked. Seems to me that both the solar panel and the wind turbine only is meant to work while the car is parked, not to charge the car while driving.
     

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