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Post by azwood on Jun 24, 2018 5:25:21 GMT -5
Looks like ill need to turn up a new turbine outer section and make the ngv but apart from that im pretty comfortable with the rest of the job
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Post by Johansson on Jun 24, 2018 7:47:30 GMT -5
Those bolts between the NGV vanes is a really stupid design.
Edit: I see now that they are just in front of a vane, they should be grinded down a bit to improve flow though.
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Post by azwood on Jun 25, 2018 9:09:31 GMT -5
Those bolts between the NGV vanes is a really stupid design. Edit: I see now that they are just in front of a vane, they should be grinded down a bit to improve flow though.Yes its an odd way to do it id prefer no bolts cant see why you would need to ever take it apart so why not weld it all
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Post by Johansson on Jun 25, 2018 12:07:18 GMT -5
He will actually have to take it apart since you canĀ“t remove the turbine wheel with the cover in place.
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Post by racket on Jun 25, 2018 17:39:19 GMT -5
Yeh , not the best way of doing things , those NGV vanes don't even have a taper on them .............I don't remember much data being produced on how it performed, it might have ended up just being a nice looking engineering exercise .
My suggestion would be for you to build with a "sore thumb" combustor and simply stick it out the side , the engine will be a lot shorter and you'll be certain it'll work , once you start playing around with modifications you're into R&D territory where years can easily go by without a working engine being produced, a basic turbo looks a simple unit , but once we start making our own engines it soon become apparent that theres been a lot more thought put into the turbo design to make it a "simple unit" .
Cheers John
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Post by azwood on Jun 25, 2018 23:04:08 GMT -5
Yeh , not the best way of doing things , those NGV vanes don't even have a taper on them .............I don't remember much data being produced on how it performed, it might have ended up just being a nice looking engineering exercise . My suggestion would be for you to build with a "sore thumb" combustor and simply stick it out the side , the engine will be a lot shorter and you'll be certain it'll work , once you start playing around with modifications you're into R&D territory where years can easily go by without a working engine being produced, a basic turbo looks a simple unit , but once we start making our own engines it soon become apparent that theres been a lot more thought put into the turbo design to make it a "simple unit" . Cheers John I agree with you it would be a lot faster to make the sore thumb design im happy to do that but just want to make it as short as possible guess i just need to get cracking on a new flame tube.if i make the outer can 300mm round and the ft say 250mm round how short do you think the ft could be
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Post by racket on Jun 26, 2018 1:45:36 GMT -5
The problem you have with a large diameter is that it needs to have multiple fuel injection points so as to "segmentalise" the cross sectional area , otherwise the length can't be shortened much .
My 12/118 engine flametube is roughly 250 mm dia within a 300 mm can , but I have 18 injectors to produce 18 "segments " , now segments really need to have a length/diameter ratio of ~2 :1 as a minimum if we want to minimise problems, for a 250 mm dia FT you'd be needing a minimum of 8 injection points to cover the cross section , so even with that amount your main body length would need to be ~250 mm long
With a fat sore thumb flametube the funnel connecting it to the scroll inlet needs to be of a reasonable length and probably ends up as a large percentage of the overall length of the flametube , as is the flametube of the GT6041 engine , it was only ~ 175 mm dia .
For a very short flametube you're probably better to go maybe just a tad larger in diameter than at present maybe 6" dia , fit 6 vapouriser tubes to get combustion started right up at the top of the flamtube ,and have the main dilution holes right before the gases enter the scroll housing , basically have the main FT body as just the Primary zone , the Secondary air entering just before the funnel starts.
Just how well such a flametube will work ............I haven't the faintest idea ........you're getting into R&D territory.
Cheers John
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Post by azwood on Jun 26, 2018 4:31:16 GMT -5
Guess i will try it and see how it goes it seems like the only option
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Post by racket on Jun 26, 2018 4:42:04 GMT -5
Yep, sometimes we need to just make things and see how they turn out , the main cylindrical body of that short flametube need only be 6 inches long X 6 inch dia , secondary holes at the very bottom , the funnel need only be ~3 inches long , you might need to check how you can fit all the Tertiary hole area into it as close to the mounting flange as possible , you may need 2 rows
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Post by azwood on Jun 26, 2018 4:43:50 GMT -5
Yep ill see how it goes its worth a shot Yep, sometimes we need to just make things and see how they turn out , the main cylindrical body of that short flametube need only be 6 inches long X 6 inch dia , secondary holes at the very bottom , the funnel need only be ~3 inches long , you might need to check how you can fit all the Tertiary hole area into it as close to the mounting flange as possible , you may need 2 rows
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Post by azwood on Jun 27, 2018 1:50:56 GMT -5
Ill draw something up and put up a pic see what you guys think
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Post by azwood on Jun 27, 2018 5:35:10 GMT -5
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Post by azwood on Jun 27, 2018 5:38:01 GMT -5
Ahh and yes i relly need to sand blast and powder coat that frame badly
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Post by azwood on Jun 29, 2018 4:37:00 GMT -5
If got a 2kg gas bottle that ill use for the domed ends its 200mm od think ill try a ft around 170mm and say 200mm for the main body before the cone so if i can make the can 350mm long total i think it will fit
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Post by azwood on Jun 30, 2018 0:22:26 GMT -5
The only real problem i see with the new ft is i will need to tip it on its side to fit this means a 90 degree bend at the turbine flange not perfect from a friction point but not much i can do also any excess fuel thats unburnt will sit in the can but ill add a drain point i guess
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