Air Scoop for hybrids


#1

Perhaps I am far behind the technology, or physics does not support it; but does using an air scoop, on a hybrid, to recover battery charge from the effects of the air moving across the car make any sense?


#2

Do you have a link you can point us to so we know what you’re talking about? Off the cuff, an air scoop would not charge a battery unless there was an impeller inside that was powering a generator. And even then, you’d need to be traveling at airplane speeds to get anything overly useful out of it.


#3

That air scoop would probably be a real negative factor in terms of the car’s aerodynamics, thus negating any benefit from air being used to recharge the battery with little windmill-like devices–or whatever type of device you envision for this purpose.


#4

Where the laws of conservation of energy are concerned, there is no free lunch.

Let’s say you put a propeller on top of your hybrid and connect it to a generator. The wind resistance it adds to the car will eat up more fuel than it saves.


#5

My thought is that an impeller driving a generator, with a large scoop necked down to magnify the air flow might work. I admit though that the Conservation of Energy principle might result in it taking more energy to drive the impeller than could be recovered by spinning a generator. I have no idea how to even begin to calculate that, hence the question here.


#6

No, it wouldn’t work, because as others have mentioned the car has to expend energy to push the scoop and the impeller through the air (and the impeller is a double hit because it has to go through the air while turning a generator).

Some airplanes have emergency generators that work on this principle - if the engine flames out they drop an impeller into the flow of air around the jet. The impeller turns and powers vital systems so that you can get the engine (hopefully) restarted. But that only works because it’s using 400+mph air to spin the impeller, and it’s for emergency power when you’re in trouble - you don’t see them trying to use the impeller to reduce the power load in normal flight to save fuel, because it wouldn’t.


#7

Shadowfax

Thank you.


#8

bandjean, the answer to your question is still “no.”

It doesn’t matter if you use a large scoop or a small one. Narrowing the neck down won’t magnify air flow, it will restrict it.

Perhaps you should google “perpetual motion machine” for better understanding. Questions like this are why I think Physics should be a required class for a high school diploma.


#9

It won’t magnify air flow, but it will increase the velocity of the air stream.

Wouldn’t increase it enough to give you anything useful (although if you get the airflow up to a high enough speed and tune the impeller right, it’ll sound like a turbo :wink: ).