Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Wind Turbine on a Car

  1. Nov 23, 2013 #1
    First of all, I have read some of the previous posts that related to this topic, but they are closed.

    I am not looking to solve the world's energy crisis, but I was wondering if there was a way to harness some of the energy given off as friction from the drag of a car. I was looking at some of the embellishments on my excursion (clearly not made to be aerodynamic), and I found that there were several different grooves that could easily be made into something like a wind tunnel. So, my question is whether it would increase the drag to cut the ends open and install a small turbine, more so than it could create.
    Please keep in mind that fact that there is already a preexisting body where it would be, so to simply say "it's impossible due to conservation of energy" is not helpful nor necessarily true.
    EDIT: I may not have been clear enough as to what I was trying to ask. I would use the turbine as a generator for energy, to be used in the engine in some form or another. Specifically, I was looking at adding a unit that created Hydrogen from water, to enhance the gas and make the car more fuel efficient. But, being that cars are dreadfully inefficient, would it even be worth it in the end? That is, in the sense of energy, not dollars.
     
    Last edited: Nov 23, 2013
  2. jcsd
  3. Nov 23, 2013 #2

    A.T.

    User Avatar
    Science Advisor
    Gold Member

    If there is no true wind (relative to the ground), I don't think this makes sense for cars.

    But airplanes, have to create lift, which induces vortices. And this specific loss form can be harvested with wind tip turbines (slide 21):
    http://www.dept.aoe.vt.edu/~mason/Mason_f/WingtipDevicesS04.pdf
    But it is probably simpler to use winglets and other shapes that reduce the vortices in the first place.

    Another way for planes to recover energy lost to drag are boundary-layer ingestion engines. The body accelerates the air, and the engines recover some of that kinetic energy by working more efficiently, than in the freestream.
    http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_09_30_2013_p40-619758.xml

    As for ground vehicles, they can use the true wind relative to the ground to propel themselves. To go directly upwind, they need a turbine:

    https://www.youtube.com/watch?v=F7PNSyAfCjk
     
  4. Nov 23, 2013 #3

    OmCheeto

    User Avatar
    Gold Member
    2016 Award

    Last edited by a moderator: May 6, 2017
  5. Nov 23, 2013 #4
    Fair enough. I hadn't seen that particular post, which would have saved me quite a bit of time...
     
  6. Nov 23, 2013 #5

    OmCheeto

    User Avatar
    Gold Member
    2016 Award

    I'm not trying to discourage you. Your question, and subsequent edit, show that you are not a dullard. Somewhere in this forum, someone posted something almost identical to what you did. I responded with something to the effect; "Idea stolen. Thank you."

    I will have to find that person one day, and give him/her their $20,000,000 reward.


    --------------------------------
    Daddy Ombucks...... Ha!
    Ok to delete, infract, and ban.
     
  7. Nov 23, 2013 #6

    Baluncore

    User Avatar
    Science Advisor

    Any turbine added to a car would increase drag and so fuel consumption more than it could possibly generate.

    It is often possible to get a 20% improvement in fuel economy from a vehicle by the addition of airflow controlling profiles. You can also get a 20% advantage by driving 10% slower on the highway. Reducing the weight of the vehicle is also beneficial, especially in hill country or stop/start conditions in a city. These methods are way ahead of any co-generation available, which would actually cost you more fuel.

    Some methods of reducing vehicle drag are; boattail plates or base flaps that reduce drag at the tail by confining the eddy flow behind the vehicle so as to not increase it's aerodynamic profile. Using skirts along the sides of the vehicle can have quite a significant benefit in cross winds.

    Finding ways of increasing vehicle economy while remaining within the regulations and not obstructing other road users is a much better investment than researching co-generation.
     
  8. Nov 24, 2013 #7
  9. Nov 24, 2013 #8

    A.T.

    User Avatar
    Science Advisor
    Gold Member

    Only if you have true wind.
     
  10. Nov 24, 2013 #9
    Faster than wind

    Sail boats can go upwind faster than the wind. It is well known fact

    http://upload.wikimedia.org/wikipedia/en/thumb/0/0e/True_Wind_vs_Apparent_Wind.png/550px-True_Wind_vs_Apparent_Wind.png [Broken]

    http://en.wikipedia.org/wiki/Sailing_faster_than_the_wind
     
    Last edited by a moderator: May 6, 2017
  11. Nov 24, 2013 #10

    OmCheeto

    User Avatar
    Gold Member
    2016 Award

    Did you ever see my post regarding my research of the NASA test vehicle studying this? It seems to confirm your statements. It was another variation of a "Wind Turbine on a Car" thread.

    My favorite post from that thread was by Berkeman.

    11 year olds have an excuse to be crackpots. All others are doomed to be italicized....... :biggrin:
     
  12. Nov 24, 2013 #11

    Baluncore

    User Avatar
    Science Advisor

    Yes I did. I am aware, but the OP asked a different question.
    The subject of this thread appears to have now morphed from miniature surface turbines on/in the surfaces of the vehicle to major vehicle extensions in the form of wind powered vehicles.
     
  13. Nov 24, 2013 #12
    I don't think Betz' law is valid here. The reason that you can't get all the power of the incoming wind, with a stationary windmill, is because the windspeed behind the mill can't go to 0, because the air couldn't get away.

    With a car windmill however, It doesn't matter that you can't slow down the wind to 0 (in the car frame), because the force on the car will be less if the wind isn't completely slowed down.
     
    Last edited by a moderator: May 6, 2017
  14. Nov 24, 2013 #13

    rcgldr

    User Avatar
    Homework Helper

    Assuming a zero wind (relative to the pavement) condition, then the power consumed by the turbine equals the net drag of the turbine times the speed of the car (ground speed and wind speed are the same). With any normal power conversion device, the power output is less than the power consumed (input), so the turbine on a car ends up being a net loss.

    Regarding the other posts about wind powered vehicles, these require a non-zero wind speed relative the ground in order to function. I assume this was not the intent of the orginal post.
     
  15. Nov 24, 2013 #14

    berkeman

    User Avatar

    Staff: Mentor

    Thread closed for Moderation...
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Wind Turbine on a Car
  1. Wind Turbine (Replies: 2)

  2. Wind turbine (Replies: 3)

Loading...