Compressed air for drag reduction ( Coanda slots )

[itjstagame]

Weird the article (the original post) says that the pulsed air comes from the slots on the side of the trucks (the ones one person thought were inlets). I don't know why it would be advantageous to have a high pressure zone here, unless they're just directing them to increase the speed of the air.

Someone also mentioned something about .25psi, I couldn't find that mentioned anywhere but that means that redirecting high pressure from the front to low pressure in the rear would not work, .25psi to me indicates that they want to turn the rear into a high pressure zone, but I think the best you can do with ducting is just to fill the vacuum (you'll never get higher than 0psi).

I haven't been able to EVER find the article, but when I was at RPI I was shown a paper once by a researcher there that was using cylindrical speakers for air flow control. He had these levating camera robot things and would pulse a frequency through speakers on the side and it would create a fake pressure zone that would cause the robot to rotate.

He had actual wind tunnel (like model test bench wind tunnel) picture of the cylinder off and on and it was a marked improvement. I'm talking like 6 years ago and have been looking for the article ever since.

Basically though I've always wanted to read more, I mean you can all picture a cylinder (so a circle) crossways in a wind tunnel, circles create horrible drag behind them and are not areo at all. He had a slot on the back of the cylinder that would some how create air/sound bubbles from a pulsed speaker and created a 'fake' aircraft wing looking shape in the next wind tunnel test. It was amazing to say the least.

[aerohead]

Originally Posted by itjstagame

Weird the article (the original post) says that the pulsed air comes from the slots on the side of the trucks (the ones one person thought were inlets). I don't know why it would be advantageous to have a high pressure zone here, unless they're just directing them to increase the speed of the air.

Someone also mentioned something about .25psi, I couldn't find that mentioned anywhere but that means that redirecting high pressure from the front to low pressure in the rear would not work, .25psi to me indicates that they want to turn the rear into a high pressure zone, but I think the best you can do with ducting is just to fill the vacuum (you'll never get higher than 0psi).

I haven't been able to EVER find the article, but when I was at RPI I was shown a paper once by a researcher there that was using cylindrical speakers for air flow control. He had these levating camera robot things and would pulse a frequency through speakers on the side and it would create a fake pressure zone that would cause the robot to rotate.

He had actual wind tunnel (like model test bench wind tunnel) picture of the cylinder off and on and it was a marked improvement. I'm talking like 6 years ago and have been looking for the article ever since.

Basically though I've always wanted to read more, I mean you can all picture a cylinder (so a circle) crossways in a wind tunnel, circles create horrible drag behind them and are not areo at all. He had a slot on the back of the cylinder that would some how create air/sound bubbles from a pulsed speaker and created a 'fake' aircraft wing looking shape in the next wind tunnel test. It was amazing to say the least.

I believe that Prandtl did R&D work with cylinders with suction-slots around the turn of the 20th-Century.His work is often mentioned in slotted-wing literature,flaps and slats.

[Vwbeamer]

How about steam? The rigs make a lot heat that is wasted already, looks like steam would act pretty much like compressed air....just thinking

[BamZipPow]

Originally Posted by Vwbeamer

How about steam? The rigs make a lot heat that is wasted already, looks like steam would act pretty much like compressed air....just thinking

Carrying that amount of water to generate the steam over an extended drive would probably offset any gains you could git.

[aerohead]

Originally Posted by Vwbeamer

How about steam? The rigs make a lot heat that is wasted already, looks like steam would act pretty much like compressed air....just thinking

With hot/humid summers,perhaps AC condensate could be collected real-time as you drove,and fed to exhaust-boot-strapped flash-heater,driving it to super-heat and plumbed out to the slot,augmenting "carried" H2O.

[SvdM]

Originally Posted by max_frontal_area

...he
ran an 8" wide and 2" thick oval tube which evacuated air from the center of the bottom front of the vehicle (which was causing the lift from air damming up) through the car longitudinally exiting right behind the bottom part of the rear window. unfortunately he ended up in a higher speed class because of that mod...

So if I understand this correctly, he DID run faster because this mod helped more high pressure air to the back of the car into the low pressure area, thereby reducing drag?

Now it sounds like most posts here are theorising about almost eliminating the low pressure completely, but even reducing it by say 5% would be beneficial.

I (thus) still thing that ducting higher pressure air from the back of the radiator through a well made ram-air system, running parallel to the exhaust in the tunnel (not to increase FA) to the back, could be a positive rather than a negative, especially at highway speeds.

Yes / No

[SvdM]

Originally Posted by max_frontal_area

...he
ran an 8" wide and 2" thick oval tube which evacuated air from the center of the bottom front of the vehicle (which was causing the lift from air damming up) through the car longitudinally exiting right behind the bottom part of the rear window. unfortunately he ended up in a higher speed class because of that mod...

So if I understand this correctly, he DID run faster because this mod helped more high pressure air to the back of the car into the low pressure area, thereby reducing drag?

Now it sounds like most posts here are theorising about almost eliminating the low pressure completely, but even reducing it by say 5% would be beneficial.

I (thus) still think that ducting higher pressure air from the back of the radiator through a well made ram-air system, running parallel to the exhaust in the tunnel (not to increase FA) to the back, could be a positive rather than a negative, especially at highway speeds.

Yes / No

[mwebb]

...."I (thus) still think that ducting higher pressure air from the back of the radiator through a well made ram-air system, running parallel to the exhaust in the tunnel (not to increase FA) to the back, could be a positive rather than a negative, especially at highway speeds.

Yes / No

"....

maybe
i suggest you google "Merideth effect" before you begin your modification

[botsapper]

Ducting/exhaust tuning for better aero.

The F1 duct does not involve any pressurized or blown-air (ironically also called 'blown wing') just a pressure differential fed through slot gaps of the rear wing, cause stall conditions & lessen downforce of wings. Benefits on the top end speeds.

http://www.youtube.com/watch?v=YZ86yAAExWo

There are also the Red Bull 'blown floor' or double diffusers, to create more downforce. The rear-pointed exhaust gases help redirect, control & accelerate underbody flow for more effective venturi bottom.
Exhaust Driven Diffuser

And this year's aero trick shows up in Renault's exhaust system, blowing exhaust forward?!! Supposedly to accelerate & buildup high pressure regions @ the back.
Renault R31 Front Exit Exhausts (FEE) – Explained « Scarbsf1's Blog

[BamZipPow]

Originally Posted by mwebb

...."I (thus) still think that ducting higher pressure air from the back of the radiator through a well made ram-air system, running parallel to the exhaust in the tunnel (not to increase FA) to the back, could be a positive rather than a negative, especially at highway speeds.

Yes / No

"....

maybe
i suggest you google "Merideth effect" before you begin your modification

ch5-5