merlin
Junior Member
Joined: November 2020
Posts: 54
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Post by merlin on Nov 16, 2020 17:13:51 GMT -5
Hi Merlin A couple of corrections , the exhaust temps were in line with the design , not because of the NGV material , it'll easily cope with a temperature that the turbine wheel won't cope with . As for SFC being "high" , how did you come to that conclusion ?? Cheers John Hi Racket,
I'm no turbine expert but from the homework i did, a turbine engine efficiency is directly correlated to the temperature at the turbine wheel.
Making his NGV hallow would make it sustain a much higher temp as well as make it lighter, just some design optimisation (from my homework  ) i don't know what material the turbine wheel is made of, i was guessing inconel? Maybe?
Those were just my 2 cents 
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Post by racket on Nov 16, 2020 18:17:30 GMT -5
Hi Merlin
Our turbine wheels are OK for ~900C -1173K - 1650F as a TIT , sorta normal IC engine max exhaust manifold temperature .
High turbine temperatures also need high expansion ratios for the benefits to be fully exploited , we don't have high expansion ratios :-( so 900C is a reasonable temp to use .
Andys engine was designed for TITs of ~900C , with jetpipe TOTs of ~940K - 670C - 1240F static temp , not total temp which will be ~40C higher , but only once a suitable sized jet nozzle was fitted , or when a larger A/B nozzle fitted and the afterburner at full burn rate , at other times his TOTs will be considerably lower due to the lack of backpressure and the increased pressure ratio across the turbine stage requiring less temperature to produce the compressors power requirements.
The TJ100 is a very nice engine but a SFC of 1.138 , not that fantastic , 50 US GPH ouch!!! for 292 lbs of thrust , 140 HP piston engine and prop would give that thrust and at a quarter the fuel burn rate
And the cost of ~$US60,000 for the TJ100 kinda makes it expensive as well
What figures did you use to determine Andys engines SFC ??
I might be able to explain what caused the confusion, you need to understand that this engine is in the very early stages of development , unlike the TJ100 which has had a lot of development done on it and probably 1,000 times more money spent on it
Cheers
John
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Post by wannabebuilderuk on Nov 17, 2020 2:07:36 GMT -5
John did andy delete his account?
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Post by racket on Nov 17, 2020 2:54:43 GMT -5
Don't know , I'm only an ordinary Member
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Post by wannabebuilderuk on Nov 17, 2020 3:58:15 GMT -5
Now says "deleted" for anything he says, I'll message him on his fb page
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merlin
Junior Member
Joined: November 2020
Posts: 54
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Post by merlin on Nov 17, 2020 15:50:39 GMT -5
Hi Merlin Our turbine wheels are OK for ~900C -1173K - 1650F as a TIT , sorta normal IC engine max exhaust manifold temperature . High turbine temperatures also need high expansion ratios for the benefits to be fully exploited , we don't have high expansion ratios :-( so 900C is a reasonable temp to use . Andys engine was designed for TITs of ~900C , with jetpipe TOTs of ~940K - 670C - 1240F static temp , not total temp which will be ~40C higher , but only once a suitable sized jet nozzle was fitted , or when a larger A/B nozzle fitted and the afterburner at full burn rate , at other times his TOTs will be considerably lower due to the lack of backpressure and the increased pressure ratio across the turbine stage requiring less temperature to produce the compressors power requirements. The TJ100 is a very nice engine but a SFC of 1.138 , not that fantastic , 50 US GPH ouch!!! for 292 lbs of thrust , 140 HP piston engine and prop would give that thrust and at a quarter the fuel burn rate And the cost of ~$US60,000 for the TJ100 kinda makes it expensive as well What figures did you use to determine Andys engines SFC ?? I might be able to explain what caused the confusion, you need to understand that this engine is in the very early stages of development , unlike the TJ100 which has had a lot of development done on it and probably 1,000 times more money spent on it Cheers John Thanks Racket,
I think he said somwhere in the thread that his turbine drinks 4 liters per minutes. i'm not criticizing his work, i wish i could do the same its an awsome turbine.
Anyway, are guys using fluid simulation to help with the design or old school pen and papper math?
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Post by racket on Nov 17, 2020 16:01:53 GMT -5
LOL....pencil and paper for me :-)
If the engine flows 3 lbs/sec - 180 lbs/min of air , T2 of ~200C , TIT of 900C so a 700C rise which will need ~3.5 lbs/min of fuel (theoretically) or ~2 lpm .................the afterburner will require ~4 lpm for a total of ~6 LPM
Cheers
John
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merlin
Junior Member
Joined: November 2020
Posts: 54
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Post by merlin on Nov 18, 2020 10:01:23 GMT -5
LOL....pencil and paper for me :-) If the engine flows 3 lbs/sec - 180 lbs/min of air , T2 of ~200C , TIT of 900C so a 700C rise which will need ~3.5 lbs/min of fuel (theoretically) or ~2 lpm .................the afterburner will require ~4 lpm for a total of ~6 LPM Cheers John
Has anyone tryed double compressor for higher compression ratio?
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Post by racket on Nov 18, 2020 15:29:39 GMT -5
It can be done , but the benefits are more applicable to a freepowered engine supplying shaft power than a thrust engine , theres an extra expansion stage with a freepower , NGV then wheel , vs a single expansion with a pure jet nozzle where you end up with a very high efflux velocity with a lot of kinetic energy , but the thrust doesn't increase at the same pace as the energy required to produce it , it doesn't take much energy to get 1,000 ft/sec but it does to make 2,000
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Post by Richard OConnell on Nov 25, 2020 11:51:26 GMT -5
Now says "deleted" for anything he says, I'll message him on his fb page Not seeing anything in the admin logs where an administrator deleted the account, so he must have done it himself. This is honestly the first time I've seen someone delete their own account in the 10 years this board has been up. |
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merlin
Junior Member
Joined: November 2020
Posts: 54
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Post by merlin on Nov 27, 2020 11:22:11 GMT -5
Sad that op is gone, i hope he's alright.
I wonder how many hp his engine make
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Post by racket on Nov 27, 2020 17:52:09 GMT -5
With the right freepower turbine/transmission downstream , 200HP should be achievable
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merlin
Junior Member
Joined: November 2020
Posts: 54
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Post by merlin on Nov 27, 2020 18:37:39 GMT -5
With the right freepower turbine/transmission downstream , 200HP should be achievable Nice |
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Post by andym on Dec 19, 2020 2:31:48 GMT -5
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merlin
Junior Member
Joined: November 2020
Posts: 54
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Post by merlin on Jan 6, 2021 12:20:15 GMT -5
Can this be converted into a turbofan or is the power not enought to drive a geared fan?
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