Hi guys,
I know I have been silent a lot the past years, but one of the many many reasons was that I had some discussions about the venturi effect under cars with some people. It eventually made me decide to make a venturi and demonstrate the effect. And now I actually made a Youtube video out of it. Jeej my first actual face appeareance!
Click here: http://youtu.be/yovQMJ02uMo
So that is one of the things that has souped up my time, hope it is fun and learning to watch.
Bernoulli's principle
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saxophonias
- Posts: 2590
- Joined: Fri Jul 03, 2009 6:03 am
Re: Bernoulli's principle
So how can we make use of this principle to our intake tubes?
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Dodo Bizar
- Site Admin
- Posts: 2009
- Joined: Mon Jun 22, 2009 10:36 pm
Re: Bernoulli's principle
Silly answer would be not... if not talking carburator which utilises this principle. My video is much more useful for explaining ground effect with a good diffusor. Note however, don't misstake my 1D venturi to look like a car with front scoop, large sideskirts and diffusor, flows beneath cars are not 1D. They are at least highly 2D if not 3D in shape. Practically the best setup is a very tiny scoop (or simply rounded front bumper), flat bottom with no skirts and a large properly working diffusor (as explained in a neighbouring topic on this forum part). This will create a nice patch of low pressure around the fuel tank area giving a lot of downforce on the rear axel. See your average sportscar or racing car these days. The splitters etc. are a bit different and help create a local low pressure patch on the front axel, however miss matching both systems might result in shitty performance downforce wise. Just a little disclaimer here actually.
Though we have venturi's in our exhaust often... just in front of the cat... but that is there for a different reason. I guess.
Though we have venturi's in our exhaust often... just in front of the cat... but that is there for a different reason. I guess.
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saxophonias
- Posts: 2590
- Joined: Fri Jul 03, 2009 6:03 am
Re: Bernoulli's principle
Right! I had in mind more the venturi effect in intake tube applications. More or less the same principle apart from the type of surface?
Also, do you have an opinion about the ek9 body kit improvements? Are they designed to serve a purpose performance wise or only the looks?
Also, do you have an opinion about the ek9 body kit improvements? Are they designed to serve a purpose performance wise or only the looks?
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Dodo Bizar
- Site Admin
- Posts: 2009
- Joined: Mon Jun 22, 2009 10:36 pm
Re: Bernoulli's principle
Hard to say and I do not know the EK9 kit by heart (link for lazy me?). However generally I only think any real performance comes from the full rear filling diffusors that nicely stroke with the stock underbody of our cars and otherwise... I guess all the rest is just for looks. Maybe some very unnoticable gains with the 'soft' splitters etc.
Actually I read someone years ago saying that 'rake' is benificial. Rake is the front end being somewhat lower than the rear. That combined with a diffusor makes actually sense... this is how I think: look at your average F1 car or any racing car that has a flat floor. The flat part is always lower towards the front and is higher at it's end, still before the part where the actual diffusor starts. I guess it has to do with the 2D/3D-ness of the flow, the diffusor does its work, however the air will be sucked in along the side under the floor due to the low pressure. Instead of blocking it with skirts let it enter (no high-end racing car these days I have seen with skirts) and let it flow, any lower/more blokkage or flatter floor and the flow would probably stall somewhere and completely destroy the effect of the diffusor.
It's a bit of guess work from my side, but I try to base on what I read in some rare white papers on this subject, some flow calculations of racing cars I found on the net and most important, by going to racing conventions and dropping on my knees to study the undersides of LMP cars and such. I think one of the break-throughs in the profesional racing world on this matter was Toyota's '97 or '98 LMP1 car, the one with the first 'double diffusor'. Which means it has a flat floor with diffusor for rear downforce and something like a very large wing in the front with its 'exit flow' in the front windshield region.
Actually I read someone years ago saying that 'rake' is benificial. Rake is the front end being somewhat lower than the rear. That combined with a diffusor makes actually sense... this is how I think: look at your average F1 car or any racing car that has a flat floor. The flat part is always lower towards the front and is higher at it's end, still before the part where the actual diffusor starts. I guess it has to do with the 2D/3D-ness of the flow, the diffusor does its work, however the air will be sucked in along the side under the floor due to the low pressure. Instead of blocking it with skirts let it enter (no high-end racing car these days I have seen with skirts) and let it flow, any lower/more blokkage or flatter floor and the flow would probably stall somewhere and completely destroy the effect of the diffusor.
It's a bit of guess work from my side, but I try to base on what I read in some rare white papers on this subject, some flow calculations of racing cars I found on the net and most important, by going to racing conventions and dropping on my knees to study the undersides of LMP cars and such. I think one of the break-throughs in the profesional racing world on this matter was Toyota's '97 or '98 LMP1 car, the one with the first 'double diffusor'. Which means it has a flat floor with diffusor for rear downforce and something like a very large wing in the front with its 'exit flow' in the front windshield region.