Author Topic: Bringing the beast back to life (repair of a GR180 turbine)  (Read 4061 times)

Offline Bjorn_B

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Bringing the beast back to life (repair of a GR180 turbine)
« on: September 24, 2017, 03:11:46 PM »
Built a jet engine a few years back (GR180) and after a "mishap" it has been in parts (FOD damage to the compressor wheel)

A friend challenged me to bring it back to life, I have got two weeks... Need to run it for a demo on 6'th of October..

I need a new compressor and a new turbine wheel, new bearings.

A start was made on machining the turbine wheel blank, a hole must be drilled straight and to an exact dimension so first a jig is made to hold it in the lathe

20170924_121002 by Bjorn Bursell, on Flickr

Checking for size
20170924_121015 by Bjorn Bursell, on Flickr

Drilling holes for the clamp ring bolts
20170924_123432 by Bjorn Bursell, on Flickr

Tapping (M6)
20170924_124312 by Bjorn Bursell, on Flickr

Ready for a really difficult job, drilling inconel is not easy!
20170924_132027 by Bjorn Bursell, on Flickr

I have found a D-bit tool ground from cobalt tool steel is the easiest way of doing this. I will do some boring work and perhaps internal grinding to bring it to size in next post. This is all for now..
20170924_143035 by Bjorn Bursell, on Flickr

Online crueby

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #1 on: September 24, 2017, 03:24:26 PM »
Quite an impressive part - was the turbine wheel a casting from a master, or cast from a 3D printed mold?

 :popcorn:

Offline Bjorn_B

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #2 on: September 24, 2017, 03:29:37 PM »
I did not do the casting, it is from Jetmax (http://www.jetmax.ch/en/turbine_wheels.htm) I also got the inlet guide vane from there.

Offline Bjorn_B

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #3 on: September 25, 2017, 07:02:43 PM »
Continued work on the turbine wheel today

Hole was in the end bored to size with a small carbide boring bar (lots of resharpening with a small diamond lap)
20170925_175856 by Bjorn Bursell, on Flickr

Checking for size, getting close
20170925_184543 by Bjorn Bursell, on Flickr

Facing of the front side
20170925_192041 by Bjorn Bursell, on Flickr

Turned around and facing of the other side
20170925_192640 by Bjorn Bursell, on Flickr

Old and new
20170925_192754 by Bjorn Bursell, on Flickr

On shaft
20170925_192935 by Bjorn Bursell, on Flickr

Next up, compressor wheel machining.

Offline Admiral_dk

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #4 on: September 25, 2017, 09:13:15 PM »
Sorry Bjorn but I can't see what is wrong with the old one in the picture - can you enlighten me please ?

I'm sure that balancing the compressor and turbine wheels are a extremely important considering how fast they spin - do this require special tool to do that dynamically or can you get away with static balancing on these small diameters ?

Best wishes

Per

Offline Bjorn_B

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #5 on: September 25, 2017, 09:22:59 PM »
Damage was mostly to the compressor but I have ground away most of my balancing margin on the turbine wheel. Not much further balancing work is possible and the blade tips have struck the NGV. So it is a bit of an unknown right now and I'd better be safe then sorry with this.

Dynamical balancing is more or less a must. I'll come to that process later :popcorn:

Online crueby

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #6 on: September 25, 2017, 09:46:56 PM »
Very interesting to watch this one, well outside my knowledge range, neat stuff.


 :popcorn:

Offline Plani

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #7 on: September 26, 2017, 10:12:50 AM »
That's very interesting work you are doing here  :popcorn: I'll be following too and hope the best you make the deadline.

Offline Bjorn_B

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #8 on: September 26, 2017, 06:51:27 PM »
Thanks all!

Today compressor modification, this is a Schwitzer S200 series? wheel that needs a lot of work, it needs to be shortened at both ends as well as the whole backside needs to be re-machined. The diameter will also be taken down from about 80mm to 74mm.

First a fixture to be made, axle driven between centres, M6 thread at the end and 7mm main diameter to fit the compressor wheel
20170926_184416 by Bjorn Bursell, on Flickr

Time to start..
20170926_190736 by Bjorn Bursell, on Flickr

After rough machining the backside, the tip diameter is adjusted
20170926_192246 by Bjorn Bursell, on Flickr

Remaining boss is adjusted to diameter
20170926_193124 by Bjorn Bursell, on Flickr

Another, clamp type fixture is needed for further machining, it still needs shortening of both bosses (old and new)
20170926_193414 by Bjorn Bursell, on Flickr

Old and new
20170926_193422 by Bjorn Bursell, on Flickr

Perhaps tomorrow..
« Last Edit: September 26, 2017, 06:54:45 PM by Bjorn_B »

Online MJM460

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #9 on: September 27, 2017, 07:43:33 AM »
Hi Bjorn, great to see those 3-D impellers on such a small machine.  No tricks missed in the search for performance.

I am another following along your amazing project.

MJM460
The more I learn, the more I find that I still have to learn!

Offline Bjorn_B

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #10 on: September 27, 2017, 04:21:56 PM »
Thanks for your comments! Input/feedback is always nice

The compressor wheel is actually from a ordinary turbo compressor (can/could be bought as a spare part)  In this turbine it needs "some" modification, diameter is reduced to lower pressure ratio down somewhat I guess (keeps combustion/exhaust temps down a bit as it would overload the turbine wheel otherwise).

A bit of a golden rule is to have somewhat matched diameters of turbine wheel and compressor wheel in these contraptions.

Length of the complete rotating assembly also needs to be as short as possible to keep critical rpm higher than max rpm. So it needs to be machined both ends as well.

I'll finish the compressor wheel tonight if I can find my old fixture.  :thinking:

/B
« Last Edit: September 27, 2017, 04:26:07 PM by Bjorn_B »

Offline Bjorn_B

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #11 on: September 27, 2017, 07:07:06 PM »
Ok, a bit more done today

This is the compressor getting it's snout cut short
20170927_183357 by Bjorn Bursell, on Flickr

Done!
20170927_183750 by Bjorn Bursell, on Flickr

Bored out the alu "backplate" to accept the compressor wheel turned nose in
20170927_185805 by Bjorn Bursell, on Flickr

Then a backwards turning job (carefully)
20170927_191740 by Bjorn Bursell, on Flickr

Done
20170927_191852 by Bjorn Bursell, on Flickr

Now, this thing needs to be balanced..
20170927_193031 by Bjorn Bursell, on Flickr

Offline Bjorn_B

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #12 on: September 30, 2017, 05:25:14 PM »
Just a quick post today, printed a new balancing rig and got the computer with program working. It's been a few years since I did this so it took a while (runs windows XP, says something about the timespan here).

20170930_160815 by Bjorn Bursell, on Flickr

20170930_162540 by Bjorn Bursell, on Flickr

It is all set up for work now, but I'll have to get some modelling clay first. It is used to ge a imbalance reference/test weight and then used to get an idea of where to grind. See if I can find any tomorrow..


Offline Plani

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #13 on: September 30, 2017, 10:14:27 PM »
Looking good, Bjorn  :ThumbsUp: :ThumbsUp: :ThumbsUp:

Would you please share some more details about the balancing process and the equipment you're using for this? This is very interesting stuff.

Thanks
Plani

Offline Bjorn_B

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Re: Bringing the beast back to life (repair of a GR180 turbine)
« Reply #14 on: October 18, 2017, 07:50:48 PM »
Sadly, I did not make my deadline. Messed up one of the bearings instead  :wallbang:, these are not the cheapest thing on earth so I had no additional spares. This project is on hold for now and I'm back working on the GHT geared and retracting topslide instead...