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  #1  
Old 27-04-2016, 12:53 AM
jondee86 jondee86 is offline
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Question Nozzle spray angle...

I am looking at possible injector locations and would like to set the nozzles
so that there is no projection into the airflow, and have the tip of the
nozzle recessed 2-3 mm as per this drawing...



So if someone can advise me the injector spray cone included angle, I can
look at how this setup can be achieved on 1.6-2.0 mm wall alloy tube.

Also, I have seen some data that suggests recessing the tip promotes
better vapourisation, and I would appreciate any input indicating that this
is a worthwhile exercise.

Cheers... jondee86

PS: I do recall seeing a post that mentioned the cone angle was 80 deg,
but I have been unable to locate that again.
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Old 27-04-2016, 04:37 AM
jondee86 jondee86 is offline
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Smile Re: Nozzle spray angle and nozzle placement...

Ha... found a post that mentioned a spray cone angle of 80 deg so I guess
that answers part of my question. And while I am on the subject of nozzles
there is also the question of preferred placement for best performance.

I am putting a Sprintex S5-210 onto a 16V 4AGE engine and this pic shows
the intake and discharge ducting I will be using...



The Intake is on the right, and comprises a cast manifold with some 2-1/2"
alloy tubing. The throttle attaches to the open end of the tube. Proposal
is for one small nozzle pre-charger.

The discharge is on the left and comprises a cast manifold plus 2-1/2" alloy
tubing with three 90 deg bends. The small transition will connect the last
bend to a stock 4AGZE inlet manifold. Proposal is for one small(ish) nozzle
post-charger.

The general arrangement of the assembled pieces is as per this pic...



To date my searching tends to indicate that it is OK to locate the pre-
charger nozzle close to the charger inlet, and that the post-charger nozzle
should be as far from the inlet manifold as possible. If anyone has any
suggestions based on their personal experience of what works best, please
post them up here

Cheers... jondee86
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  #3  
Old 27-04-2016, 07:21 AM
parmas parmas is offline
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Default Re: Nozzle spray angle...

Hi Jondee,

Your setup looks sweet although for my tastes there is some extra bending there which you could experience air turbulence. If the charger was on the side of the engine going into a 45degree angle to the manifold would be ideal. Although it does not mean it will not work well eventually .

Why would you make such an impact on nozzle angle ? Some setups have nozzles pointed directly to the flow coming and work well. I have mine in a 45Degree bend.

Why hiding it between too walls ? This way injection could have more probability wetting the walls instead of mixing into the air causing liquid water to form into the intake, which is bad...

I attached where would I put the nozzle location PRE/Post Charger
Attached Images
File Type: jpg Sprintex%20ducting%2002_zpsv495wfzm.jpg (107.8 KB, 17 views)
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  #4  
Old 27-04-2016, 08:35 AM
jondee86 jondee86 is offline
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Thumbs up Re: Nozzle spray angle...

Thanks for the suggestions parmas

The layout of the ducting was dictated to a large extent by the lack of
space on the intake side of the engine, and by the fact that I did not want
to get involved with building a custom intake manifold at this stage. It was
suggested that I could eliminate all but one of the 90 deg bends on the
discharge side if I entered the GZE manifold from below. While that may
have been possible, I felt that it would starve cylinders 1 and 2.

So I went with a layout that is as close as I could get to the factory angle
of entry into the top of the manifold. I have faith that the Toyota factory
engineers did some testing on the non-symetrical runner layout to make sure
that it worked reasonably well. I have also increased the throttle size to
60 dia and all tubes to 2-1/2" to try and keep flow losses down. This is my
first venture into supercharging, so I am more interested in creating an
engine that makes driving a pleasure, rather than ultimate power.

Mounting the pre-charger nozzle in the bend seems reasonable. I think that
I would mount it square to the surface of the tube to try and project the
mist as far out into the airstream as possible (penetrate the fast moving
layer of air on the outside of the bend).

The post charger nozzle where you suggest, or perhaps in the straight
tube below the small angle bend to place it out of the way of mechanical
damge. Again installed square to the tube surface.

My interest in recessing the tip of the nozzle comes from reading this page..
http://www.alcoholinjectionsystems.c...rticles_id=100



Allowing the cone to develop before exposing it to the "shearing" effect of
the airstream seems logical to me. It will still get sheared, but the droplets
will be finer and should disperse more effectively. Sound reasonable ?

Cheers... jondee86
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Old 27-04-2016, 11:29 AM
Richard L Richard L is offline
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Default Re: Nozzle spray angle...

Looking at the angle of those nozzle, it could do with every little help to improve the atomisation. Take a look of the video below:

https://www.youtube.com/watch?featur...&v=xvSNmn6A64M
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  #6  
Old 27-04-2016, 12:32 PM
jondee86 jondee86 is offline
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Lightbulb Re: Nozzle spray angle...

Oh, I don't know what type of nozzles they are... but obviously not yours
The image was photoshopped simply to show how recessing the nozzle tip
would allow the cone to expand a little more before it was "folded over" by
airflow within the tube. I assume that even your nozzles have the water
leaving the pinhole as a solid stream which very quickly expands and breaks
up into small droplets.

My interpretation of this information is that the water leaving an exposed
nozzle would be more likely to be folded back against the wall of the tube
than the same nozzle recessed a few mm below the tube surface. However,
I'm sure that you have more than likely tested this theory in the lab. And
if experimentation shows that there is no benefit from recessing the nozzle
tip, then I'll just use the standard adapter and try and get the end of the
nozzle flush with the inner surface of the tube.

Cheers... jondee86
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  #7  
Old 27-04-2016, 05:26 PM
parmas parmas is offline
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Default Re: Nozzle spray angle...

That's why I like to put an injector in the middle of an elbow of 45degree since putting it just into a straight pipe could lead to wetting walls/inefficient dissipation.

Although I would be interested if someone prove scientifically what works best
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Old 28-04-2016, 12:55 AM
jondee86 jondee86 is offline
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Question Re: Nozzle spray angle...

Personally, I am inclined to think that placing the nozzle in the tube just
before the inside of a bend would result in the best mixing.



Using this simulation as a reference, and assuming that the spray is swept
away and remains quite close to the nozzle side wall, the spray would then
be turned around the inside radius of the bend where flow separation and
turbulance occurs. This should promote better dispersion and mixing of the
air and water.

However, this remains just a theory without any valid indication of exactly
how the spray penetrates the airstream once it leaves the nozzle.

Cheers... jondee86
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  #9  
Old 28-04-2016, 08:01 AM
jondee86 jondee86 is offline
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Post Re: Nozzle spray angle...

Been doing some searching but so far have not been able to find anything
of much use. However I did find this...



It shows, as might be expected, that larger droplets penetrate further into
the airstream. Smaller droplets are the first to be swept away. This leads me
to believe that placing the nozzle either on the inside of a bend or immediately
after a bend, would be advantageous. The larger droplets would then be
projected towards the higher velocity air on the outside of the bend, which
would help break them up and prevent/reduce any impingement on the
farside wall.

Cheers... jondee86
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  #10  
Old 28-04-2016, 10:16 AM
rotrex rotrex is offline
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Default Re: Nozzle spray angle...

Flow velocity is the fastest on the inside of a bend.
Droplets do not like to take bends. They will hit the wall and wet it.

This is the reason fuel injectors are spraying straight into the inlet port.
They are not mounted before any bends. In the old days of throttle body injection the manifolds were first designed for wet flow and they were heavily heated to let that wet fuel film on the intake plenum wall evaporate.

Water evaporates about 10x slower than methanol and much much slower than gasoline.
If you want water meth as droplets in the cylinder and not as a stream along the wall you have two choices.
Either have the nozzles in the straightest section before the inlet ports of the engine or mount the nozzle as far away from the engine as possible. In the latter case there is more time to evaporate, even if streaming along the wall. In the first case, the highest percentage of droplets will make it into the cylinder.

Calculate the g-forces in a bend of your radius at WOT and max flow. You will find numbers of 1000G and more. These are typical numbers found in vortex water separators to remove water droplets from natural gas.

In the end all loss of fluid can be compensated by injecting more or use of a higher percentage of methanol. It evaporates on the wall as well as in the air.

IMHO inject as suggest by parmas straight into the SC and then in the straight section leading into the intake plenum. Your center cylinders will receive more spray than the outer ones as the drops have to take more bends. Little you can do about it except going for a direct port set-up.

Last edited by rotrex; 28-04-2016 at 10:19 AM.
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