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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. |
#2
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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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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 |
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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 |
#5
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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
__________________
Richard L aquamist technical support |
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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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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 |
#8
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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 |
#9
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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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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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