Vortex Generators - hopefully a rational discussion.

[freebeard]

I find it interesting to bring my 30 years of aviation, aircraft modification, and maintenance and a minor in rotorcraft aerodynamics to the table to see how it can be applies to the everyday driver.

I see VG's ruffle feathers around here.

Welcome to Ecomodder.

How are you wih MS Paint? Photoshop? Scanning hand sketches? I for one would appreciate if you could document the layout on your pickup. I'm hoping it's a 1954 Studebaker.

I have never seen vortex generators not work, so I'm not a skeptic. Questions:

• Can they be placed after maximum cross-section so they don't add frontal area?
• What do you think about the theory there needs to be something to re-attach to?
• Does your theory about virtually extending the body equate to my theory about shrinking the apparent cross-section at separation, or would there be detail differences?

...and slightly off-topic:

• What's the best way to get an helicopter fuselage at scrap metal prices that could be dropped onto a VW Beetle floorpan?

Kind of like this (BD Trike bede BD5), except Bede 5Js are in short supply.

aerohead -- We crossposted. I'm going to go back and read that about 5 times, but...

*Suction and blown slots DO show a drag reduction,however,the energy required to operate the pump exceeds the energy saved.

Coanda, baby! Too bad cars don't used pumped air for engine cooling so the heat could selectively be added to the attached flow.

[aerohead]

If you could harvest all the exhaust heat to run a hermetically-sealed gas cycle turbo-compressor or turbo-vacuum pump,you might be able to augment the flow volume to the slots.This energy is being wasted and is about 33% of the engines entropy.

[freebeard]

I wonder if you could chop a turbocharger into a turbo-shaft? I like the idea of diverting the corrosive exhaust gases.

OK, Porsche use pumped air cooling! Their fan can have 5 to 11 blades depending on your backpressure needs.

Someone showed a subwoofer (I think it was a commercial product) that used a constant-speed variable-pitch propeller. It could produce notes as low as 50hz by reversing the pitch in a cycle. For your compressor/vacuum pump.

[ecomodded]

Originally Posted by aerohead

If you could harvest all the exhaust heat to run a hermetically-sealed gas cycle turbo-compressor or turbo-vacuum pump,you might be able to augment the flow volume to the slots.This energy is being wasted and is about 33% of the engines entropy.

that is a lot of hp that is available for recovery , once a method is devised.

Worth trying to figure out to put it mildly.
First thing comes to my mind is steam regeneration next is making it a electrical generation system that turns heat into electricity for storage and use later for the cars needs.

Combine both ideas and its a steam engine for electricity production.

[MrInstrument]

Originally Posted by MetroMPG

This is the one style of car I'd actually like to try them on - small cars with very short rear decks. Tuft testing the deck would reveal whether it was a good candidate for a VG test or not.

I sold the truck and just purchased the new test vehicle. 2014 VW Golf TDi.

[aerohead]

Originally Posted by freebeard

I wonder if you could chop a turbocharger into a turbo-shaft? I like the idea of diverting the corrosive exhaust gases.

OK, Porsche use pumped air cooling! Their fan can have 5 to 11 blades depending on your backpressure needs.

Someone showed a subwoofer (I think it was a commercial product) that used a constant-speed variable-pitch propeller. It could produce notes as low as 50hz by reversing the pitch in a cycle. For your compressor/vacuum pump.

30-years or so ago,the Israeli's had solar ponds with immersed heat exchangers
full of refrigerant which would flash to superheat and high pressure which would impell a turbo-generator to provide electric power day and night.
We might be able to harvest the exhaust heat to directly run the turbo-compressor or turbo-vacuum pump to create the Coanda curtains.
With say,33% of the fuels energy lost down the tailpipe,this seems like an interesting field to plow.
J.J.Cornish III of the AIAA has demonstrated very 'fast' aft-bodies with perfectly-attached flow using suction (which dates to the 1920s with Ludwig Prandtl's STOL aircraft research).We just need a cost-effective source for the input energy.
Since a turbocharger is designed to harvest a pressurized gas stream,it seems like the logical candidate.By using the blowdown energy,then all the waste heat as possible,a compound turbo system might pay dividends via the slot system.Closer to an adiabatic engine.

[Superfuelgero]

Originally Posted by ecomodded

that is a lot of hp that is available for recovery , once a method is devised.

Worth trying to figure out to put it mildly.
First thing comes to my mind is steam regeneration next is making it a electrical generation system that turns heat into electricity for storage and use later for the cars needs.

Combine both ideas and its a steam engine for electricity production.

At that point, might as well go full steam. Fyi, for the racers amongst us, the landspeed records for steam are ridiculously old and low.

[Smokeduv]

With say,33% of the fuels energy lost down the tailpipe,this seems like an interesting field to plow.

Actually, I find this 33% accurate, and is the basis of the new regulations on the F1. They basically run the turbo without wastegate so, instead of sending the excess exhaust gases through the wastegate, they send all the gases through the turbine and control boost and turbo speed with a motor generator, which recovers that unused thermal energy into electrical energy. That energy is stored in a battery and used in different areas, one being at the same electric generator, reversing it and making it a motor and thus, eliminating turbo lag (I'm not good explaining this, you are the experts, but you get the idea). With this they could lower fuel consumption by 30% in a very high performance car (which is a bit controversial, because the fans wants power, not a fuel-efficient car, but anyway).

[aerohead]

Originally Posted by Smokeduv

Actually, I find this 33% accurate, and is the basis of the new regulations on the F1. They basically run the turbo without wastegate so, instead of sending the excess exhaust gases through the wastegate, they send all the gases through the turbine and control boost and turbo speed with a motor generator, which recovers that unused thermal energy into electrical energy. That energy is stored in a battery and used in different areas, one being at the same electric generator, reversing it and making it a motor and thus, eliminating turbo lag (I'm not good explaining this, you are the experts, but you get the idea). With this they could lower fuel consumption by 30% in a very high performance car (which is a bit controversial, because the fans wants power, not a fuel-efficient car, but anyway).

It's good to hear that F1 is exploring technology which may actually trickle down into consumer products.Thanks for the info.

[freebeard]

Will BMW's electric turbocharger end turbo lag?

BMW was talking about this in 2011.