Building JetOne Gas producer for ultralight turboprop engine

[elmo0104]

So what is conclusion guys? There is no way to support good lubrication without the pump? How those "snorkles" tubes works John?I mean are you happy about results?

[racket]

Hi Peter

High speed rolling element bearings need either a good supply of lubricant for lubricating and cooling, I use ~1 litre/minute to each bearing , or an oil mist system where the airflow does the cooling and the small amount of oil the lubrication.

From what I gather from your explanation of your system , you only want a small quantity of oil and no airflow , this won't work as theres a lot of heat buildup which needs to be removed otherwise the bearings will fail .

The RC micro engines use oil mist , actually a fuel and oil mix from the fuel supply and a large amount of air which is a total loss system , this does work but its imperative to get it "right" otherwise you'll end up wrecking your rotating assembly when the bearings fail ..............believe me ,its not a nice sound to hear :-(

You also need to take into account the various rotor vibration modes when using a turbocharger rotor which is designed to run in a thick film of oil to control those vibrations , "hard" rolling bearings ideally need some sort of "flexibility" built into their mountings , I used bronze cups with O'rings on their OD , the cups provided the required endfloat in the system as well as preload from the spring/s forcing the cups apart.

Simply grinding down a turbo shaft and adding a couple of ball races will most likely produce an unhappy outcome unless there is a lot more thought put into the process.

My personal preference, after a lot of headaches with "balls" , is now for using standard turbo brass bushes , balls can be made to work , but you need to do the research

Cheers
John

[elmo0104]

I will probably use the jurnal bearings in my next project. I can see benefits of them just now, not before. My idea for lubrication system actually include air as cooling and small amount of oil mist. That is why I want to have drains. I want to force the air and oil mist in to the shaft tunel and then do not burn it at the turbine wheel but collect it in to the drains and then put it back in to the oil container. Separate the oil from the air on the fine steel mesh. Leave the air in to the compressor inlet. I'm not sure that this will work but I'll try probably.

John you mention about the orings in the shaft tunel to damp vibrations. I was wondering wat they are for at 4.50' in this movie. Now I know. Will they do the job? Now I have "slip" fit for bearings, I can bore the shaft tunel to lose fit and add orings like in the movie below.

www.youtube.com/watch?v=oYpG0HDcFsA

[racket]

Hi Peter

The amount of oil that is actually needed for lubricating the bearings is extremely small due to the very light loads , but the cooling requires a lot of air .

Total loss oiling has been used on large commercial aero jet engines in the past .

I feel you are trying to over complicate the process with attempting to "recycle" the small amount of lubricant .

You can't feed the recycled air back into the compressor as it will still have some oil in it and will end up contaminating the comp wheel surfaces to which dust and dirt will adhere and reduce comp efficiency .

If you want more info on micro type engine lubrication checkout the GTBA www.gtba.co.uk/

Cheers
John

[elmo0104]

Now I see. You are right recycling air is no needed. Air can be vented to the outside of engine. For lubrication only add a smal amount of oil to that air before it comes to shaft tunel. I'm waiting for ordered literature about jets.

Cheers
Peter

[jetjeff]

Hi Peter,


If you are still undecided on how to provide lubrication to your bearings, you may want to contact Horace Tl Ho at jet beetle at this email address; ; [e-mail] He may provide advice to you, he will help amateurs like us.

John knows WAY more about turbines, than me, but it wouldn't hurt to get a third opinion.

Jeff

[racket]

Hi Peter

Oil mist lube is used in industry for high speed tools , it might pay to do some research

Cheers
John

[elmo0104]

Hi there.

I'm still waiting for literature. Any one help with clearence value? I want to bore shaft tunel and make grooves(or one groove) for oring to fit bearing on it for dump vibrations. My Outer bearing diameter is 28mm. 8mm of depth. What size of grooves and orings should I use? Will the VITON orings be OK?

Cheers
Peter