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Post by racket on Oct 31, 2012 19:55:02 GMT -5
Hi Steve
Won't the NGV expand into the "cold" case once the engine is running and take up the clearance, you might find that your sleeve will only be a stopgap measure until such times as the expansionary forces once again produce a "cold" gap .
On my engines theres a slip joint between the exducer shroud and the outer case , I leave several thou radial clearance on this when machining it up as the gap soon closes once the temps come up .
The shroud is ~5" dia , ....with a 800 deg C temp rise the stainless will expand by ~ 0.088" , whereas the outer can with say a 200 C rise will only be a quarter of that leaving ~0.066" unaccounted for , still a lot more than the clearance I leave , but the tight fit between shroud and can will transfer heat into the slipjoint and expand it away from the shroud to the point where an equilibrium is reach and a relatively airtight joint is achieved .
Could there be any other reason for the temp rise ??
Cheers John
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rythmnbls
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Post by rythmnbls on Nov 1, 2012 20:06:40 GMT -5
Hi John,
I hadn't even considered thermal expansion, I ran the numbers and you're right, the gap should close up once the NGV gets up to temp. The sleeve serves a secondary purpose of locking the rear ring of the CC in place, so I'll leave it installed.
As to why the temps have dropped is a bit of a mystery. The only other change I made was fix a leak on the suction side of the fuel pump which was allowing air bubbles in to the fuel supply. The bubbles were very small so I'm not convinced that change could have caused the temp drop, but, one never knows with these engines ;D
Regards.
Steve.
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Post by racket on Nov 1, 2012 23:45:43 GMT -5
Hi Steve
LOL............theres always lotsa options when it comes to tracking down an "off design" parameter, .......trial and error is often the only way to find it .
Cheers John
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rythmnbls
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Post by rythmnbls on Nov 13, 2012 20:41:08 GMT -5
Here's a clip of the latest run, rotor speed was about 55K RPM through most of the run. It was mentioned earlier in this thread that these engines are thirsty, this clip is proof Regards, Steve.
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Post by Richard OConnell on Nov 16, 2012 3:12:06 GMT -5
Wow, I'd say that engine has a drinking problem That start still looked a bit toasty, still having problems with the dremel?
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ripp
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I'm sorry, I don't speak english, so I torment you (and myself) with a translation program,Sorry
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Post by ripp on Sept 26, 2013 14:14:56 GMT -5
Hi Steve, I just read your thread T04E turbine-compressor great work!!! my opinion, you lose too much power at the NGV and turbine, Therefore, exhaust gas temperature is too high See the difference in the Pictures Regards Ralph. translate.google
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rythmnbls
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Post by rythmnbls on Sept 26, 2013 21:19:17 GMT -5
Hi Steve, I just read your thread T04E turbine-compressor great work!!! Thanks! Not sure how you are arriving at this conclusion, the design value for EGT was 645 degrees C, the actual measured value was 625 degrees C. There's a video clip at the photobucket site showing the running temps. Those photos look like the 66mm or 70mm NGV and turbine wheel from Jetmax, neither of which are suitable for this version of the engine. The NGV and turbine wheel in use are 75mm and the engine cycle values were calculated to match these components to the garret compressor wheel. Regards. Steve.
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ripp
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I'm sorry, I don't speak english, so I torment you (and myself) with a translation program,Sorry
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Post by ripp on Sept 27, 2013 0:49:32 GMT -5
Hi Steve, The photos show an NGV and turbine wheel with 74mm diameter of JetMax. you must contact him he has other NGV and turbine wheels which are not listed on the home page. and as for the EGT: you now have 625 degrees C without nozzle. watch this video, it is a similar turbine works colder with a 14- 16 kg thrust www.youtube.com/watch?v=7k-F6nRcPfU (2:40) www.youtube.com/watch?v=tccqPOTJgqUone of the best turbine manufacturers for me is Alfred Kittelberger runs over 11,000 U/min stable and has over 18 kg thrust www.youtube.com/watch?v=22osaWstQzYRegards. Ralph translate.google
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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
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Post by ripp on Dec 29, 2013 5:52:05 GMT -5
Hi Steve, what about the GR-180 turbine is they running?
Regards.
Ralph
translate.google.at
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rythmnbls
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Post by rythmnbls on Jan 5, 2014 12:47:40 GMT -5
Hi Steve, what about the GR-180 turbine is they running? Regards. Ralph translate.google.at Hi Ralph, The turbine is not running at the moment, I managed to damage the turbine wheel and NGV in a failed experiment with combustor flame holders. When the weather warms up I will make replacements and update this thread. Regards. Steve.
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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: 236
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Post by ripp on Jan 5, 2014 16:24:44 GMT -5
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