Definition of the "venturi" system

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Other
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by Other » 19/04/07, 05:50

Hello
A venturi is something simple to achieve, still it must be done in the right size,

We take the example of a venturi in the intake of a diesel engine with a reactor which is powered by a small water carburetor, this is my case and that of most of the assemblies at ZAC

If the venturi cole is small it makes a significant suction at low speed and too great a water consumption.
If the venturi neck is too big, it only sucks at high speed and too little water consumption.
we know that a venturi its suction is not linear when we pass a lot of air its suction increases rapidly, this is why all the carburetors which work according to the principle of the venturi have an automatic system to deplete running at full power ..
Normally when the venturi neck is well chosen in a panton the water consumption is adjusted for usual regimes
in my case from 90kmh to 120kmh, if I drive at 130 and 140 the reactor cools down it passes too much water, if I roll at 90 it is hotter, at 80 kmh it starts to cool a little because the engine generates less of heat on the reactor.
So a venturi acts as automatic only on a range which is sufficiently released for our uses

It is enough to measure the reactor output to understand well.
for use at all speeds, you must control the water flow, or operate with a carburetor that has an emulsion well.

With a bubbler the problem is the same as with a simple carburetor it is the suction in front of the reactor which determines the quantity of humid air which passes in the reactor.
We have to wait until the reactor is hot to pass water and avoid cooling it so that it becomes liquid on the rod.

Andre
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RolCopter
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by RolCopter » 19/04/07, 17:08

Bonjour à tous

It is true that it is not complicated the mechanics of fluids lol : Mrgreen:

http://fr.wikipedia.org/wiki/Th%C3%A9or%C3%A8me_de_Bernoulli

All you have to do is take into account the density of the fluids, their speeds, their temperatures, their densities and the characteristics of the pipes in which they circulate.

And as a bonus it works in both directions, at work we use venturis to suck the edge cuts on the thermoformers (packaging under food gas - food packaging).
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zac
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by zac » 19/04/07, 20:37

RolCopter wrote:Bonjour à tous

It is true that it is not complicated the mechanics of fluids lol : Mrgreen:


You know, I haven't been in school, so a venturia bicone I do it at random and I test. it works so much the better it doesn't work I make another one.

if I have the space 30/100 of conicity in entry and 7/100 in exit it is generally not bad.

if there is no room we see : Lol: : Lol: : Lol:

@+
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by Other » 19/04/07, 21:40

Bonjour à tous

It is true that it is not complicated the mechanics of fluids lol


If it was so simple why did the carburetors use atrifices to have an acceptable mixture at high revs?
the well of emulsion has for role particularly to make the automaticity and also bubbles.
certaint make a secondary entry when the venturi pulls too much
What I mean the portion (linear) or rather usable with a primary carburetor. is quite narrow.

To make a venturi it is a trifle, but to have a constant flow whatever the air which passes by the collar with a simple nozzle this is not tpa srealist it has an adjustable nozzle in a way to decrease the flow at high speed, c is why a reactor that works well at 100kmh with the same settings has too much water at 150kmh
despite the fact that the reactor receives more heat.
it is not completely self-regulating,
with a well calculated school diameter, it can have worked well on a wider range of speeds.

You can calculate as you want it must also take into account the heat of the reactor which does not always follow the air flow especially when you go up a slope, or a slight descent, the downstream diesel a lot of air but little gasiol = little heat, the amount of water must be controlled ...
and when we are dealing with a tubing full of elbow pulsating inlet it is not a simple calculation of venturi as on industrial gas ovens (I worked on this for quite a long time)
you have to make several to find the right recipe

Andre

Single venturi and double venturi both the air inlet is annular (no tube in the venturi cole just a slot.
The double venturi has a greater depression.

venturi pic226.jpg


Venturi which comes from an airplane to operate the gyroscope, applicable for pantone suction

double venturi pic225.jpg
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the joint
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by the joint » 19/04/07, 22:23

I found it simpler: I prick the output of the reactor under the carburetor like that no need for a venturi !! : Cheesy: : Cheesy: : Cheesy:
Well it's true it's not very constructive as a remark ... : Mrgreen:
At the beginning I did not understand where the venturi was located in a carburetor, but in fact it is its general shape which is in venturi, incredible I had never been careful!
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RolCopter
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to take in the second degree




by RolCopter » 20/04/07, 16:37

Hello everyone

from André
If it was so simple why did the carburetors use atrifices to have an acceptable mixture at high revs?


Totally agree with you André, it was just to be taken in the second degree. My experience in terms of carburetion (venturi) I acquired it when I was little (not even major lol) by repairing mopeds, solex and then motobecane motorcycles D45, D52 etc. My favorite reads were the mechanical topics in Motorevue. To return to the carburetor and the needle wells, to modify the aspiration into the well in question, conical needles were used to increase the diameter of the emulsion in relation to the lifting of the bushel. I am not too much to use the carburettors on the G system, the density of the water is far from that of petrol and the vacuum through a reactor must be difficult to exploit.

Note: my preference is for vacuum fuel (menbrane)
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Less pollution is already a great result
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by Other » 20/04/07, 18:45

Hello
the winter car is a bubbler gele oblige, the summer car c, is a small ultra-simple carburetor all in brass house construction
easy to unclog and functional, a simple small venturi of 4 mm at the neck with a double point as a nozzle all solder with silver
no float the tank slightly under the level the suction does the rest it even sucks a height of 250mm
so I maintain a light differential with a flat tank.
my sytem approaches a GV except that I do not maintain water in sle GV the engine sucks with the carburetor what it needs, these drops of water hit the exhaust and are routed in the reactor with a certain amount of air ...
Simplicity is difficult to do, but it is the basis that every good handyman should know.
Andre
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Re: to be taken in the second degree




by zac » 20/04/07, 18:52

RolCopter wrote:Note: my preference is for vacuum fuel (menbrane)


In theory me too, but the only vacuum carburetor that is available to me are those of 2 times (chainsaw, brush cutter etc ...) They make gas pump at the same time; So for them to work properly, they need an alternating pressure depression cycle. Very difficult to obtain on a 4 stroke 4 cylinder.

that's why I use either: mob carbs or model carbs with a scooter tap (vacuum).

@+
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RolCopter
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by RolCopter » 20/04/07, 21:34

good evening everyone

from Zac
In theory too, but the only vacuum fuel available to me


I kept a nice vacuum fuel and bushel of Austin Mini
but it is a little big on the other hand the Japanese in one manufactured in quantity of the smallest for motorcycles, I do not know if you can find some on your island.
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RolCopter
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An effective venturi is still very bulky.




by RolCopter » 06/05/07, 23:25

good evening everyone

An effective venturi is still very bulky.

http://www.ozone.ch/gasandwater/mazzei/3090.htm

But hey my next pantone mount I would do it on a truck lol.
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