Injecting prior to turbo comp' impellers

[masterp2]

Those are good concerns Joe.

If injection pre-turbo is implimented with moderation, I don't think you will have any problem. Freezeup more of a concern for many. I have been thinking along the lines of a temperature switch post-IC that would inhibit pre-turbo spray if not hot enough.

You really should play around with atomization, though. You need a very fine mist, more like fog. The biggest danger is impingement on the blades from larger particles. Maybe try fog nozzles under the highest pressure you can get, at least 100 psi. Multiple nozzle array vs single large one.

I am going to be trying some of this as our weather warms up.

[doctorfrag]

Thanks, hopefully I'll get a chance to chat with Richard as he really knows his stuff

I need to get a mist rather than droplets as you say. Gelf got some moderate results, it is hard to know whether that was just due to more WI, not specifically pre-turbo. Also I think the pre-turbo will only work if you are out of your efficiency island with your turbo, in other words the turbo is too small



Here you can see, on the right vertical line ,that at 6500 rpm, even at 1.2bar I am actually off the map :shock: :wink: , although I normally will only run 1bar or so at the redline. I am mapped to 1.3bar, so really my turbo is only efficient between 3000 and 4500 rpm, so if I can shift the island to the right I will be pleased

Joe

[masterp2]

Can you post a better image?

Present day feeling is that the effect of misting will move it to the right as you say. Usefull for all temps and speeds however, apparently most helpful at increasing compressor efficiency, so more of the work performed is applied to compression, less to heat loss: hence higher comp ratio (boost). Add a little fuel (meth), lower charge temps, all = power increase.

[doctorfrag]

this is for a T3 '50' trim, as I can't get a compressor map for my turbo.

Mine is a T25/28 hybrid, the standard turbo on fiat coupe 20vt, and using a larger compressor wheel '60' trim, has a T25 inlet.

I'm going to try a 0.3mm jet preimpellar to see if this makes a good difference.

do you have any further thoughts?

regards

Joe

[masterp2]

It is my opinion that a nozzle that is oriented with the air stream is much more effective, than a nozzle pointed at the opposite wall of a conduit. Keeping water from recombining into larget drops and facilitating evaporation, rather than pooling so much, as evident in videos. A nozzle with a narrow angle of spray, vs a wide angle. 2 smaller nozzles, perhaps back to back, one pointing into the wind, one pointed leeward (with the wind). A simple plumbing T could do it. Just need some way to keep the fitting aligned, concentric with the conduit.

If you do something like this, i am very interested in your results. Just remember that you need heated air to hold the water, so be sure pre-turbo misting cannot occur till relatively high boost. The lower the boost cut-in, the more likely it is you will have condensation in the IC. And this will occur at higher speeds where the IC is most efficient. In reality, since misting is only a short duration event, I don't see any real need to be concerned about condensation, since even if there is some, it will quickly evaporate (within seconds) in a heat soaked IC. The atomization challenge is the big hurdle.

There is another article on this board about swirl flash atomization you might find interesting.

[doctorfrag]

Thankyou Michael, for you points. :smile:

I have a short induction route pre-turbo with a metal pipe and could run a jet into there, or jets.
My current jet comes on at 1 bar boost, and I would probably keep the same there, you have reassurred me about the condensation, as it would only come on when the boost is on, in test we recorded post turbo temperature of 135degC, so I don't think much water would hang around in the intercooler for long.

I will speak to richard about the atomisation, I run at 1.3 bar midrange which drops to around 1-1.1 bar at the redline, fitting a bigger downpipe will help the turbine efficiency, but this science has got me thinking about improving the efficiency, I amy even see more boost?, but as said befoer ned to get the water atomized.

regards

Joe

[masterp2]

1.3 bar pump pressure? Doesn't the aquamist go higher?

the following increase atomization effectiveness (smaller particle size):

higher pressure
lower viscosity (warmer fluid)
lower surface tension (analagous to lower viscosity but using surfactant)
smaller nozzle flow capacity


ideally 500-800 psi and fog nozzles would get you all the "fog" you need, but the practical limit to pressure, hoses and fittings is a limitation. Where this may not be so important in post IC misting, your effectiveness will be measured in your ability to achieve the smallest micron size possible, for the pre-turbo application. Some think it is only important in order to keep blade damage at bay. Not so. With only milliseconds of interaction during compression, it happens so fast that so much of the water cannot evaporate, because even a 50 micron droplet takes time. And the turboine efficiency will depend on the amount evaporating during compression. There is no help to turbine efficiency if water is evaporating after the heat has been produced, and the particle is downstream. Hence the repetition on stressing atomization.

I believe aquamist did not design for pre-turbo. While I have no numbers on aquamist nozzles, I doubt they are set up to "fog" under low pressure. Some nozzles are better than others though. Perhaps someone can host a particle distribution chart on aquamist, I have not seen one. Bete makes a PJ nozzle that is a impingement fog nozzle. I will be experimenting with them under 100-200 psi. I have some charted data on those. If interested in researching further, get aquainted with Sauder Mean Average particle size. You may find that even at 100 psi, 50-60 micron is a common SMA. Fog is considered 20 or less. So it's not an easy challenge. But you can play around. Maybe a little soap will make a big difference. Do an easy experiment. Get a narrow funnel and a quantity of water. Add a drop of DW detergent, see how much faster the water flows thru.

just some thoughts. Post your results. Looking forward to it.

[doctorfrag]

thanks Michael,

I meant 1.3 bar turbine pressure.

Yes, from what I've read Atomisation is the key, it is no point having larger drops, as you may as well have the nozzle downstream then.

I am running the Aquamist race pump, will keep you informed

regards

Joe

[janis]

I've got all the stuff at home to start pre-turbo injection, but I'm still not sure about a few things.

So I've got a few questions (and forgive me please if the answers are to be found in this thread already, although I read it completely, I might have missed something):

1) Is it wise to inject methanol into the turbo (80W/20M)? Isn't the stuff too aggresive for the poor turbo?

2) I got a suggestion (from Richard, thx) to inject pre airfilter. But I have a few reservations:
2a) Will my MAF survive?
2b) My airfilter is a Cold Air Intake, foam with oil. Will the methanol ruin the foam? Or will the water stay in the filter until it forms puddles and ruin both my MAF and the turbo?

Thanks,

Jains

[PuntoRex]

I suspect the air filter would gather the droplets into much bigger ones. The droplet sizes are supposedly bigger then the meshes of filter, thus physical contacts should happen & slow the droplets down....

And no matter how the droplets change, the MAF would certainly be affected by the water, especially hot wire type. It's hard to predict the changes to sensor reading & it's reliability.