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Power generation & drag reduction (from "paddle wheel" mounted in rear turbulence)

Came across an interesting paper today that discusses power generation and drag reduction.

http://www.openfoamworkshop.org/2009...gnon_paper.pdf

Quote:

USING OPENFOAM TO MODEL ENERGY TAKEN FROM THE SWIRL
BEHIND A CAR

Louis Gagnon
Marc J. Richard
Benoît Lévesque
Dept. of Mechanical Engineering
Laval University
Québec (Québec) Canada

Abstract. A two-dimensional numerical analysis of the Ahmed body was performed using the k-!-SST turbulence model
from the OpenFOAM software. The analysis was then modified to include a rotating paddle wheel that captures energy
from the swirl that forms behind the vehicle. The rotating wheel is modeled using a General Grid Interface (GGI) and the
energy captured is calculated with the help of the forces library of the OpenFOAM software. Power generation reached
16.1 watts at optimal conditions. Total drag reductions up to 8.2% were found. Most computations were run in parallel
on a dual core computer.

I don't know how well it will translate to real life but it is interesting.

Reading the introduction, so far, so good. I'll take a look to all the document

Quote:

It was found that the rotating paddle wheel can generate 16.1 watts while reducing drag by 7.7%.

Interesting. People have been dreaming about this forever...... :D

http://www.chemistryland.com/CHM107/...indTurbine.jpg

from: CHM107 Energy: Quiz

(I kid.)

The rear is the ideal place for something like this, sure you are not going to get a whole lot of power out of it because there is not a lot of straight air flow, but it will help smooth the air flow and generate power at the same time.

I wonder if some of those piezo electric ribbon generators would do well, they have a very low power output but they also just need to flop around, like what happens when you have turbulent air flow.

Perhaps at some point they will do 3D modelling and wind tunnel evaluation.
Part of my brain says,eliminate the vorticity in the wake which the paddle wheel would harvest.
The other side says,if you're stuck with vorticity,then make the most of it.
The National Highway Traffic Safety Administration would have a say in the U.S.A. over any protruberance at the rear of a vehicle such as a paddle wheel.
'guess we'll see where it all goes.