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ok so instead of describing the theory behind this one, let me just describe my prototype, and i think the idea will become clear.
1) get a plastic 2 liter pop bottle
2) throw the cap away
3) cut a hole in the middle of the bottom of the bottle about the same size as the natural hole on top
4)
get ahold of a condum (unused if possible)
5) cut the very tip of the condom off, essencially making a latex tube.
6) attach one end of the latex tube to the natural opening in the 2 liter bottle, and use some sealant to keep it in place with an air tight seal.
7) pull the free end of the condom THROUGH the inside of the 2 liter bottle, and get its open cut to where the new hole in the BOTTOM of the 2 liter is (this may be trickey)
8) attach this end to the mouth of the hole in the same way, with the sealant.
**now what you should be looking at has the VERY loose approximation of the shape of a torus (i use the word torus, just to clairify what surfaces are inside of what). also, you should be able to see daylingt when you look through the bottom whole of the bottle straight up through the letex tube.
9) in the SIDE of the 2 liter cut a small hole (half centimeter in diameter)
10) get some vaccume line from autozone (a foot will be enough) and put one end a couple centimeters into the small hole in the 2 liter. (dont let it stick far enough in that it gets anywhere near the condom running through the middle)
10) attach this connection with the sealant
now what you have is the bottle/condum torus, with a tube coming out of the inner volume.
now blow into the vaccume line. the condom should puff out in the middle, making the passage from top of the bottle to the bottom smaller. suck on the vaccume line. the condom should expand in the middle, making it bigger.
as a throttleing device, you wouldn't care much about increasing the cross sectional area (sucking on the vaccume hose). but you WOULD want to decrease the cross sectional area to "throttle" the air that will be flowing through it.
this throttle would have an advantage over normal TBs (ThrottleBodies), since there is no butterfly valve in the center. this would be extremely beneficial at wide open throttle, when in a normal TB, the only thing the butterfly valve is doing is creating an air flow restriction and making a LOT of turbulance (which further inhibits flow).
i also thought of the "poor man's" way of testing the flow of my design versus a normal TB. all you need is a vaccume cleaner, a musical instrument that changes pitch based on how hard you blow it (like a whistle), some sound recording software that lets you view the recorded wave graphically, and a microphone (dont even need a good one, headphones pluged into the mic input would work). oh yeah, you would also need a normal TB with the same cross sectional area to test it against. actually, you wouldent need it to be the same cross sectional area, as long as you knew what the area was, and have a basic understanding of fluid flow math equations.
practically in a car you would use hydraulic fluid to "blow" into the inlet tube, and obviously the materials would be tougher than a damn condom.
also, whatever you do, do NOT try to salvage this condom for it's intended use! you will end up with sealant on your penis and a child.
Similar Device
http://www.redvalve...ual_10_reasons.html
[jhomrighaus, Aug 02 2006]
Venturi flow
http://www.foxvalve...ameset-venturi.html
Take a look at the flowmeter loss, and the cavitating venturi [Ling, Aug 03 2006]
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thanks Lt_Frank, im still trying to think of a fail safe system, so if there were a failure the throttle would stick close, not open...thats the one thing im not sure about how to do. maybe a double redundant pressure system could do this, like what goes on inside a break master cylinder... i'll post when i have a better idea |
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Why do you think that this would eliminate turbulance? Any Change in pressure will generate a certain amount of turbulance in the Air Stream, and the shape required is continuously variable. Also you need to keep in mind that the pressure differential of the air through the Throttle plate at WOT is almost nil. The Plenum is running at near ambient pressure so the flow through the Throttle plate has little or no impact on the performance of the engine. Much Greater impacts occur in the intake runners. |
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In general the biggest issues with turbulace take place at partial or 0 throttle, when there is a very large pressure differential across the gap. |
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Keep in mind also that a certian amount of turbulance is required to properly mix the Fuel and air(this is why improperly done Porting and Polishing can seriously impare an engines perfomrance.) |
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I am also wondering about throttle response on a system like this. I would guess that it would be very slow compared to most mechanical systems. |
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tip of the hat to what you said about the responce time on my idea, that could be a disadvantage if it couldent be sufficiently minimized during actual implimentation. although pnumatic fluid is a non-compressable fluid, so i reckon the "esophagus" would be as quick as your actuators...after all, F1 engnes use pnumatic actuators to achieve previously unimaginable linear speed from their valves (20,000RPM). i stand by the idea that this system would eliminate turbulance...at least almost all of it, but i didnt fully take into consideration what you said about the NEED for turbulance. i will have to re-think my ideas concerning this. i will model this goemetry in SolidWorks and post a picture online so you know excactly the shape i mean...(think of a woman with an "hour glass" figure that has the ability to shrink her mid-section to the diamater of a pin) does anyone know where i can get a trial version of COSMOSflow? for doing finite fluid analysis on SolidWorks parts??? |
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about $100 to a cash strapped senior mech eng at the nearest university should do for the COSMOS modelling. |
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As to "although pnumatic <SP> fluid is a non-compressable <SP> fluid"... um, by definition, pneumatics is the use of gasses at differing pressures to do work. Gasses are compressible. I think you're thinking of Hydraulic fluids, which, whilst compressible, are only really compressible in a dynamic sense, and generally don't change volume in a hydraulic system. Pneumatics do work by being compressible. |
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I'd seriously advise against attempting CFD (Computational Fluid Dynamics) without the associated computational mechanics or at least engineering degree (which you may have, and if so, my apologies for the assumption). You possibly do not appreciate just how complex such operations are. Without the right tutelage, I’d estimate your chances of producing realistic results are roughly zero. The real problem is that with CFD, as with FEA (Finite Element Analysis), it’s pathetically easy to produce results, but very very very difficult to get correct ones. |
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</end rant/>
The basic concept is, however, quite good. Although, I’d hazard a guess that this device, if it had the same response time as a normal throttle body, wouldn’t actually do anything, except change the throttle-response curve. You wouldn’t actually GET any more power out of this, because at full throttle, you’d get the same airflow. And at partial throttle, you’d get less; it’s only the response curve you’re changing. AFAIK all the polishing is for maximum airflow at open throttle. But then again, what would I know? I’m only looking at this in terms of the airflow. |
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yes you're right, i did mean hydraulic. also, you are correct in pointing out that i am a bad speller, which i realize.
i will have my mechanical engineering degree from the university of michigan in 8 classes. i have taken a few fluids classes, but i have 2 more to take for my degree. and there are ways other than mathematics or FEA to tell if something flows better than something else. |
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Gets my vote for not being made of metal --- its nasty stuff... [bring back wood]! |
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If you reduce turbulence through the carburettor in "throttle wide open" position, you may gain in flow rate and in power. There's no point in reducing turbulence in partial throttle positions, as it's the reduction in flow rate that gives you control of the engine's output.
Your idea might reduce "wide open" losses, but the greatest advantage might be simplifying or doing away with the idle and off-idle circuits - because in idle, you'd still be producing sufficient velocity through the reduced-section venturi to draw the fuel. |
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auricom_mech, I think you could take a look at venturi flowmeters, which are used as instrumentation. They are very well known, and I think that all sorts of models are available.
There isn't much difference to what you are thinking. See link for starter. |
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thanks for the links guys.
jhomrighaus:
i do like that pinch valve idea...maybe i started off my idea by making it too complicated. it looks like those pinch valves, slightly reconfigured, would work just as well, if not better in an auto.
Ling:
yeah ive seen thoes delta P velocity meters before but i had forgotten all about them! thanks for the reminder. maybe i can make one myself...a home made one might not be too good at telling the net flow, but it would probably be good enough at seeing improvements or declines in flow...(what's the term for that? accurate, but not precise?) |
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