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Post by madpatty on Oct 26, 2020 3:09:55 GMT -5
Hi Jeff.
I am not sure. It’s a normal production turbine shaft for HX82 turbocharger.
Guess would be high carbon steel of some grade which can be induction hardened where brass journal bearings run and then ground to final size.
Regards. Patty
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Post by racket on Oct 26, 2020 3:15:05 GMT -5
Hi Patty This is how my 12/118 NGV looks imgbb.com/Cnc2m6X , still shiny "chrome" after lotsa starts Cheers John
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Post by madpatty on Oct 26, 2020 3:28:39 GMT -5
Hi Racket. I don’t have much pictures of the inner flametube. But here are all the pictures of various angles that I have that may be helpful. Regards. Patty
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Post by madpatty on Oct 26, 2020 5:34:33 GMT -5
Hi Guys. Another question that came to mind after I made my own full complement bearings is- How many bearing balls should be used for making a normal bearing to full complement? Should it be the maximum number of balls you can fit? In my normal 6003 bearing, they by default come with a 10 x 3/16” balls and you van fit maximum of 17 balls. But 17 balls ‘feel’ sorta tight. Though bearing rotates freely but it seems there will be lot of inter-ball rubbing. Here is 1 bearing that I test made with full complement of ceramic balls- Thanks. Patty
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Post by finiteparts on Oct 26, 2020 6:03:06 GMT -5
Patty,
The scallop on the Holset wheel is very large. How does the blade length match the recess behind the wheel? I am wondering if there is a higher amount of exhaust gas getting behind the wheel as compared to John's design.
Maybe if this is the case we can come up with a heat shield that you could add into the recess.
Good luck, Chris
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Post by finiteparts on Oct 26, 2020 6:52:58 GMT -5
If you have a picture of the turbine wheel installed so we can see the backface gap and how the bolting recess aligns to the aft hub of the turbine, that would help us alot.
- Chris
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Post by madpatty on Oct 26, 2020 7:02:05 GMT -5
If you have a picture of the turbine wheel installed so we can see the backface gap and how the bolting recess aligns to the aft hub of the turbine, that would help us alot. - Chris Hi Chris. I hope this drawing will answer your question. Thanks Patty
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ripp
Veteran Member
I'm sorry, I don't speak english, so I torment you (and myself) with a translation program,Sorry
Joined: January 2013
Posts: 230
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Post by ripp on Oct 26, 2020 9:04:29 GMT -5
Hi Patty, you should perhaps install a new spacer, so the cooling air is forced through the front ball bearing and cools the front and rear bearings. Alfred Kittelberger introduced this type of cooling air flow to his turbines in 1999. is it possible that the hot gases flow backwards through the shaft tunnel and that the lubrication cannot work because it is being blown in the wrong direction? Cheers Ralph translate.google.at
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Post by madpatty on Oct 26, 2020 10:42:33 GMT -5
Hi Ralph. I think I already have that kind of spacer in ghis design. It’s just not show in the drawing. below pictures are from old design but is carried forward exactly in my redesign. Thanks. Patty
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Post by racket on Oct 26, 2020 16:07:34 GMT -5
Hi Patty Thanks for the extra pics, especially this one ibb.co/QrpKHcG .........does it look familiar to my 10/98 jetandturbineowners.proboards.com/attachment/download/26 You need an air deflector at the diffuser outlet to split the flow and radial vanes to eliminate/prevent swirl after the air is deflected, you aren't getting sufficient air going down the back of the diffuser wall to "pressurise" your bearing air bleed holes, and to supply air along the shaft tunnel OD to "pressurise" your bleed air holes across the NGV , resulting in too much hot gas at the turb bearing. My personal thoughts are that radial inflow turbine wheeled engines need a deflector whereas axial wheeled ones don't due to the radial position of the flametube outlet , radial turb has it at the outer diameter whereas the axial wheel at the inner radius . Just my 2c worth :-) Cheers John
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Post by wannabebuilderuk on Oct 26, 2020 16:25:39 GMT -5
I have absolutely no idea on half the stuff in this thread but man do I enjoy reading it all and how everyone works together perfectly to help solve the problem. Glad I'm part of this community!
Also racket that 10/98 picture hurts to look at, can't imagine how annoyed you felt when you realised it failed..
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Post by racket on Oct 26, 2020 16:48:52 GMT -5
Hi Ben
Thats what the Group is all about :-)
LOL......I don't know if I felt annoyed , more resignation to the fact that development work doesn't always go smoothly , it can be frustrating at times but theres satisfaction when the issues are solved , as was the case with the 10/98 , simply adding the air deflectors cured the problem , it forced air into the centre of the engine rather than it only going along the outside of the flametube .
Patty changed the original diffuser design , this then created a new set of circumstances with regards airflow , to overcome them we need to make other changes to the engines original design .
We'll get it sorted eventually
Cheers John
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Post by racket on Oct 26, 2020 18:59:06 GMT -5
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Post by finiteparts on Oct 26, 2020 19:36:53 GMT -5
Hi Patty, I think you may have a few issues with the turbine bearing region. First, it looks to me (as best as I can estimated from the few pictures) that your bolting pocket that you have machined in there is exposed to the hot gas flow. This is not good since any "cooling" jets that you try to introduce will be totally insufficient to fill the pocket. Usually, you try to have the jets introduced behind the backface of the turbine wheel, with the idea that the cooling gas will try to purge the space behind the turbine wheel and not allow hot gas to get ingested behind the wheel. Here is my attempt to see how the bottom of the scallop between turbine blades matches up with the bolting pocket...I know they are not in the same direction and there is a bit of perspective error, but I think it scales pretty close. If this is correct, then your hot gas flow has direct line of sight to the pocket and hot gas will just get churned up in there. The cooling jets that you have in there will actually act to pull hot gas into the pocket by driving local vorticity. If this is an accurate representation of the geometry that you have in your engine, you need to do something to fill this pocket. And here is an attempt to draw in what I am thinking. The second major issue that I can see is that you have a giant, easy conduction path straight to the outer race of the bearing. The flange on the center tube acts like a giant fin to pull heat from the very solid and thick NGV plate. The bolts themselves are bathed in hot gas on the one side and then they conduct that heat straight to the center tube flange, right above the bearing. Turbochargers have heatshields as a means to control the ability of the hot gas path thermal energy from heating up the aft bearing, which would coke up without it. Ball bearings can coke up too and this varnish begins to act as an insulative layer, impeding the bearings ability to shed the built up thermal energy into the oil. I hope this makes clear why I was asking about the scallop and the turbine picture. If this is the case, then we can start to think about ways to thermally isolate the turbine bearing. Have you seen any oil staining on the NGV plate or any other signs to lead you to believe that the total loss oil system is discharging properly out the aft end? Also, be careful reading into the heat stains on the front diffuser structure...you melted a bearing there and the thermal staining could be due to that only. Good luck, Chris
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Post by madpatty on Oct 26, 2020 21:14:03 GMT -5
Hi Patty Thanks for the extra pics, especially this one ibb.co/QrpKHcG .........does it look familiar to my 10/98 jetandturbineowners.proboards.com/attachment/download/26 You need an air deflector at the diffuser outlet to split the flow and radial vanes to eliminate/prevent swirl after the air is deflected, you aren't getting sufficient air going down the back of the diffuser wall to "pressurise" your bearing air bleed holes, and to supply air along the shaft tunnel OD to "pressurise" your bleed air holes across the NGV , resulting in too much hot gas at the turb bearing. My personal thoughts are that radial inflow turbine wheeled engines need a deflector whereas axial wheeled ones don't due to the radial position of the flametube outlet , radial turb has it at the outer diameter whereas the axial wheel at the inner radius . Just my 2c worth :-) Cheers John Hi Racket. Interesting observation. Those pics indeed look similar. I will try to come with some similar looking air deflectors towards inner flame-tube. Regards.
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