Aerocap Thesis from 2009

[bondo]

Found another Engineering students Thesis on aerocaps I thought you guys might like to review.

There are some nice CFD graphics and a curved Aerocap was found to reduce the Cd the most. The fuel efficiency gain comes out to about 1 mpg in the calculations derived from the students CFD simulations.

I have experienced a higher percentage of fuel efficiency gain at around 3 mpg or 15% at sustained freeway speeds. Round.boater has seen a 15% increase also in the fuel efficiency of his truck since running an Aerolid, which he has recorded in his fuel log here on ecomodder.

round.boaters fuel log

http://ecomodder.com/forum/em-fuel-l...vehicleid=2565


In the last paragraph of the thesis, on future work, the student states a need to test an aerocap on a truck in the real world along with other aerodynamic devices.

Link

http://csus-dspace.calstate.edu/xmlu...pdf?sequence=1


Bondo

[Old Tele man]

...nice to read about the 3" and 6" height front air dams too!

[bondo]

Originally Posted by Old Tele man

...nice to read about the 3" and 6" height front air dams too!

I also like that different angles of the aerocaps were simulated. 12 degrees looks to be the best.

[t vago]

Dang me... My cap was indeed too aggressive. I had a 20 degree downangle. The coefficient of lift for 18.77 degrees increased by 63% over the baseline, in that paper. No wonder my aerocap flew!

Thanks!

[bondo]

Yeah t vago, lift is good for aircraft, bad for aerocaps.

The wind tunnel tests I did on my Aerolid in the A2 wind tunnel in North Carolina showed a significant increase in lift too. My lid is around a 12 degree slope. The students thesis shows a reduction in lift, at 12 degrees, which does contradict the data derived from test on my lid in the A2 wind trunnel.

[redneck]

Would adding tailplates lower the cd on the 3D aerocap?

>

[t vago]

Originally Posted by redneck

Would adding tailplates lower the cd on the 3D aerocap?

>

I can definitely tell you with 100% certainty, that the answer to your question is a firm and definite maybe.

[d0sitmatr]

excellent read !
although I did notice here was not much variation between a standard aerocap @ 10 vs @ 12. however, the angled cap did provide a much greater difference over both straight 10/12.
going by that study, the best gains would come from a front air dam @ 6" coupled with the curved (angled) aerocap.
which also makes me feel much better since that was the direction I was going to take with my Ranger prior to trading it

[aerohead]

I sure wish we could get away from 'angles'.Angles don't occur in high-performance structures,only compound curvature.
One can only discuss a particular angle,tangent to the body curvature,at any particular point,not some general area of the structure.
The folks did a lot of work.And the values are appropriate for their model,nothing else.They've essentially re-discovered Paul Jaray's work of 1922.
One would be warned if they believed any fast and hard rules would apply to these results when extrapolated out onto the general pickup truck population.
Sure,compound structures are the most complicated forms,most difficult to create tooling for,most expensive.But if you want the best quality fluid flow over a structure,you're hard pressed to beat them.
And if you ever intend to have all available kinetic energy transformed back to static pressure,and achieve lowest drag,you're pretty much locked in to using these forms.
Anywhere,except the automotive industry,will you find anything but these complex forms being used to eek out every bit of available energy when moving structures though fluids,be they gases or liquids.
Okay,rant over.Thanks Brett.

[slowmover]

A good read, all the way through.