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Post by racket on Mar 26, 2014 16:59:11 GMT -5
Hi Miuge Have you looked at RC Dons project www.rcdon.com/html/gr-5_turboshaft_engine_project.html , a simple welded up axial fan . I also used a homemade axial fan for my turboprop PJ engine , it "survived?" 20,000 rpm with temperatures of >900 C www.youtube.com/watch?v=uqMn0A2aUdo . A simple ~150mm axial wheel running at ~15,000 rpm and using inexpensive karting sprockets ( no gearbox) with sealed ball bearings on the shaft would produce ~80% of potential horsepower , this will be better than using the undersized S300 with only 60% of the flow but at 4 times the rpm , rpms that require precision and sophistication to work/survive. A S500 shaft would be OK , just some duct work to make , your welding skills look pretty good so it shouldn't be a major problem . Cheers John
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miuge
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Post by miuge on Apr 2, 2014 15:58:06 GMT -5
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Post by racket on Apr 2, 2014 20:03:19 GMT -5
Hi Miuge
A 90 mm exducer will be more than adequate to flow your gases :-)
Cheers John
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miuge
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Post by miuge on Apr 3, 2014 2:41:07 GMT -5
Hi John,
Just wondering what would be turbine's rpm for maximum output. I looked compressor- and turbine maps for similar Garrett models and end up to something below 30,000rpm. Since we got a 12" rear wheel, we need a greater reduction ratio than sprockets only would allow. My previous calculations show that 1400rpm at rear wheel equals 120kph. Maybe we could use karting chain in first stage reduction and then add a heavier chain for the final ratio..
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Post by racket on Apr 3, 2014 3:28:43 GMT -5
Hi Miuge
As you'll be able to flow your full mass flow from the gas producer there'll be less requirement to force the rpm to maximum to achieve reasonable horsepower outputs .
A freepower turbine can produce 80% of potential power at 50% of its rpm .
Good quality racing kart chain can cope with 20,000 rpm , with an ~8 :1 overall ratio for the sprockets it'd only need a normal sort of heavier chain sprocket ratio to achieve your speeds .
Cheers John
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Post by Johansson on Apr 5, 2014 0:06:36 GMT -5
As I wrote in the PM, try to keep the revs down since the wheel has seen some rubbing and probably a fair bit of high temps during the engine failure that wrecked it, and two short (couple of mm´s) hairline cracks can be seen between two of the blades on the inducer at the thin edge going radially inwards.
I don´t think it is a problem as long as you don´t stress it overly much, but you should be aware of it.
Cheers! /Anders
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miuge
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Post by miuge on Apr 5, 2014 2:07:11 GMT -5
Yep, revs will be low compared to what it spins normally, absolute maximum of 20,000rpm at topspeed which is about 25% of intact wheel's max rpm.. Also it won't never suffer such temperatures neither. Yesterday I tried welding 3mm aluminium with my cheap chinese TIG, I've only tried a few times AC welding, results: i187.photobucket.com/albums/x281/mice325/IMG_3198_zpse6694758.jpgAluminium fuel tank would be nice :-P
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metiz
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Post by metiz on Apr 5, 2014 7:56:31 GMT -5
Not bad at all! Looks like there might be some thungsten inclusions inside the 2nd pic weld. Try keeping the tip clear of the puddle
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miuge
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Post by miuge on Apr 15, 2014 4:29:55 GMT -5
Hi metiz, Thanks, I'll try to improve my skills cause I've got a lot of aluminium works on the way with my car project. Tip clearance seems to be crucial part of succesful welding result
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miuge
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Post by miuge on Apr 19, 2014 16:11:09 GMT -5
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Post by Johansson on Apr 19, 2014 22:34:17 GMT -5
Great to see that it arrived in one piece, have fun with it!
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miuge
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Post by miuge on Apr 20, 2014 8:02:12 GMT -5
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miuge
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Post by miuge on Apr 27, 2014 7:09:14 GMT -5
Turbine chra done, I made a short movie of manufacturing: vimeo.com/93057278Next week we'll make the rest and I'll edit movie part2
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Post by Johansson on Apr 27, 2014 12:40:34 GMT -5
Nice video! You seem to have access to a fine workshop. I am looking forward to the part where you manufacture the snail housing, might snatch an idea or two from you for the boat engine build.
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miuge
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Post by miuge on Apr 30, 2014 3:42:51 GMT -5
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