Turbocharger inlet

[kilrbee]

Presently have a turbo that is run off the right side of the map, NE side of the map to be precise. It runs into very low efficiency numbers, and the boatload of heat it is crating is problemeatic. GT40 compressor, with inlet temps of 220F, higher elevations, trying to push 50 lb/min, at 25-29 psig discharge. Temps up to 600 F at discharge. I am planning to evaporate up to 15 gpm using the disturbance potential of the compressor to obtain quasi-isothermal compression. I believe I will reduce discharge temps at least 150 degrees.

I am looking at designing a waternozzle mount, 30mm in front of the compressor. Are there any likely concerns for inducing surge? Anyone with experience with resonance failure of such a device? I have modeled it with 3 radial ribs that appear like an airfoil, center mounted nozzle.

Any feedback appreciated.

 

[turbomotor]

Hello Kilrbee,

Anything upstream of the compressor can be a problem in that an aerodynamic wake may excite blade vibration, leading to blade high cycle fatigue. Also, unvaporized water droplets impinging on the leading edge of the wheel can cause severe erosion.

Two suggestions:
1. Make sure the angular location of the 3 radial ribs is asymmetric so that you don't set up a perfectly sync'd 3 times per rev excitation.
2. Harden the wheel with a very thin electroless nickel plate or Type III hard anodize.

 

[kilrbee]

very useful, thanks. I would not have thought of symetry. Id there anything I should consider in the aero shape of the fins?

http://www.thedieselgarage.com/forums/showpost.php?p=415394&postcount=82

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[wgknestrick]

Sounds like a sequential twin turbo setup?

Couldn't you fit a small IC to cool the charge before the turbo inlet? Reducing the inlet temp will give great results in efficency.

 

[kilrbee]

I can see where you would think that, but no, a single charger. With such a lousy hot air intake that up to 240 F has been logged in the intake.

The reality is that a simple CAI will be the cure. But I am going a step beyond that.

 

[JimCasey]

The purpose of a turbocharger is to compress more OXYGEN into the combustion chamber. If you evaporate a lot of water into the air downstream of the turbo, you displace a lot of the potential air that could go into the combustion chambers...and steam does not support combustion. You would get energy scavenging, and some power from the intake stroke, and the steam would likely act as an antiknock agent and also reduce NOx in the exhaust.

For the same amount of water, I would rashly venture an opinion that you would get more power with a water-cooled intercooler. The direct water injection Might show up as a benefit to fuel economy as long as you only measure miles per gallons of fuel and not miles per total gallons of liquids consumed.

 

[kilrbee]

A big part of the objective, is to take an inefficient charger operating off the right side, and real it in.

Inasmuch, there are much more benefits than just cooling charge. Lower drive pressure=lower egt, higher comp efficiency=more MAF...etc.

I realize that water has a small displacement affect. But if the MAF goes up while turbo rpm comes down, and less charge heat is a benefit, then the objective is covered, which is to reduce induction source overheating of the radiator.

 

[XXXLR8R]

Normally, I would disagree with Jim Casey on the injected-water evaporation rate causing a significant decrease in the number of oxygen molecules transpiring the intake tract, but in this case - 15GPM water injection???

Sounds more like a sump-pump! Bet you'd hydro the cylinders and window the block...

Si Vis Pacem Para Bellum

 

[kilrbee]

That is a typo. sb 15-20 gph.

 

[ivymike]

Sounds more like a sump-pump! Bet you'd hydro the cylinders and window the block...

you might be surprised... I certainly was... Using a clear pvc inlet tube, I've personally seen several liters of accumulated liquid water from the charge cooler flow suddenly into the intake of a running diesel with no ill effect (aside from a few seconds of rough running and lots of steam out the exhaust). Since I was standing next to the running engine, I fully expected that my last meal would be a piston.

 

[wgknestrick]

You have 2 problems with your setup according to the info provided.

1. (as mentioned above) You need a CAI to reduce the inlet temps down closer to ambient. 200F is too hot to begin with and is really hurting power. This alone might bring you into "the zone" for little $ and effort invested. Low hanging fruit.

2. You are asking too much out of your turbo and need a larger one, matched to your needs. This is the ultimate source of the problem and the item that needs "fixed". A GT42R would probably suit you better, but they certainly aren't free or cheap.

Water/Methanol injection will not be a silver bullet to your problems, but can add a good deal of anti det to your fuel system and gain some HP. It can compensate for some of your setup's shortcomings, but will not "solve" them.

 

[kilrbee]

What is low hanging fruit?

 

[wgknestrick]

A farming expression meaning "A decent return for little effort". Low hanging fruit is much easier to pick compared to the ones at the top of the tree.

 

[kilrbee]

Thanks, I finally looked it up. I guess as an engineer, I fall into the classic "no common sense" stereotype.

To address your statement, I don't think it is the case. I just determined that the intake has a 5 psi total pressure drop, and that the hot side plumbing is 2-4 psi, depending on IAT. Subtracting 5 from the denominator probably speaks for itself. In determining the PR at 6000 ft. 36/(14.7-2-5)=4.6

 

[ivanheow]

gt40 at 50 lbs should be ok by the maps shouldnt it ?

 

[kilrbee]

Not if the cold side losses are 5 psi. PR goes off the map.

 

[ivanheow]

good point bee , i wonder if the chaps looked at the holset turboes .they tend to go high in the pr ,and big ones off plant machinery may be cheap eg an hx 55 or 50. barring that a cooler on the inlet air seems to bring it all back down on the pr side .