Toni
Member
Joined: December 2020
Posts: 26
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Post by Toni on Dec 2, 2020 10:21:46 GMT -5
Hi everyone
I´m Toni from Finland and I have HX 60 jet engine, it run whit diesel and works nice but now I need to build afterburner, any advice for that?
I appreciate all help.
Best regards Toni
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merlin
Junior Member
Joined: November 2020
Posts: 54
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Post by merlin on Dec 3, 2020 17:40:16 GMT -5
Hi toni, welcome on the forum As far as i'm aware of jet engines that have afterburners use cool air from the first compressor/fan to cool the walls of the afterburner. Without it, your afterburner wint last long.
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Post by racket on Dec 3, 2020 17:57:03 GMT -5
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Post by Richard OConnell on Dec 4, 2020 1:21:24 GMT -5
Welcome aboard Tony! A lot of commercial diagrams of afterburners are quite complex to replicate for the things we do. Often times, we just put a few spray bars in the tailpipe, sometimes with what is called a 'flame holder' in between to create an area of low velocity airflow to make it easier to keep the afterburner lit. Lighting the afterburner can also be a bit tricky. A lot of DIYer's do a 'hot streak', or basically squirting a VERY brief puff of fuel just before the turbine. That fuel ignites and is carried into the tailpipe where it mixes with the atomized fuel from the spray bars, igniting the afterburner. If you consider this method, be very careful. Hot streaking isnt particularly great for a turbine and if a solenoid hangs open and you keep spraying fuel, you can almost guarantee your turbine is going to vaporize. You'll want a timing mechanism that keeps the hot streak solenoid open for like a quarter second and shuts it until you activate it again. If you're looking for some reading material, check this out: authors.library.caltech.edu/21303/1/251_Zukoski_EE_1978.pdfGood luck!
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Post by racket on Dec 4, 2020 2:55:37 GMT -5
Hi Richard
Nice document , LOL....a bit of "light" reading material ;-)
Cheers John
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slittlewing
Senior Member
Joined: November 2017
Posts: 458
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Post by slittlewing on Dec 4, 2020 14:02:57 GMT -5
Welcome to the forum Toni. If you look at the picture on the last post on page 2 (racket link above), those dimensions I used are for a 63mm inducer. That afterburner is based on dimensions well proven and worked out by Richard staveley (jetric on this forum). The afterburner works by making a big step change in diameter, making a big turbulent toroid of air that anchors the flame and stops it blowing out. The other option is to use “flame holder” I.e. blockage but I have no experience with this.
You will also find details of fuel ring, which is 8mm OD 6mm ID stainless tube with 8x 1mm holes, fed by an 044 fuel pump. I used a 1.3mm restrictor before the fuel ring to make the pump more “controllable” for my electronic setup but you could use mechanical bypass instead. Ignition is from a normal spark plug with the gap opened out
Cheers
Scott
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Toni
Member
Joined: December 2020
Posts: 26
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Post by Toni on Dec 6, 2020 6:55:43 GMT -5
Thank you very much all this information, what kind of fuel you use in afterburners, oxygen, diesel, or what?
Best regards Toni
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Post by wannabebuilderuk on Dec 6, 2020 9:24:01 GMT -5
Toni, the afterburner works on the principle of burning extra fuel to increase the thrust so you'd use a secondary fuel pump (standard car efi pump is good enough for the high flow rate required) to push more of the diesel/kerosene/whatever is your main fuel to get the extra thrust.
Ben
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Toni
Member
Joined: December 2020
Posts: 26
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Post by Toni on Dec 6, 2020 9:29:03 GMT -5
Thank you Ben, if I spray diesel to afterburn chamber, does it flame whit out ignition?
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Post by wannabebuilderuk on Dec 6, 2020 11:58:23 GMT -5
Most likely no unless your flametube is incorrect and the combustion is still happening past the turbine wheel (if that was the case you'd see flame constantly and your wheel would be glowing red/in a melted puddle). The effect of smoke generation you see in these jet trucks is as far as I know done by spraying the fuel in against the hot metal of the afterburner but not igniting it so it is vaporised into a large smoke cloud. As soon as you hit the ignition it will ignite and produce extra thrust instead of smoke. The simplest way for an afterburner is to use a secondary igniter to spark when the fuel is flowing or a hot streak which is where you inject fuel just before the turbine wheel in the base of the flametube for no more than a second or it'll potentially melt the wheel. You can see what I mean in this video youtu.be/c53yDbsFcNI
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Toni
Member
Joined: December 2020
Posts: 26
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Post by Toni on Dec 6, 2020 12:45:42 GMT -5
Now I have 230V oil heater ignition system, where I can buy 12V ignition system?
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Post by wannabebuilderuk on Dec 6, 2020 13:51:31 GMT -5
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Toni
Member
Joined: December 2020
Posts: 26
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Post by Toni on Dec 6, 2020 14:19:04 GMT -5
Thank you very much.
Now I have 3,5 + 3 gal nozzles and 1,3 bar boost, what you think how big nozzles are maximum for my HX60?
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Post by wannabebuilderuk on Dec 6, 2020 15:28:05 GMT -5
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Toni
Member
Joined: December 2020
Posts: 26
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Post by Toni on Dec 7, 2020 2:27:26 GMT -5
In that case max consume is 12,5 gph and whit afterburn even 50 gph, is that all 37,5 gph going to afterburner or can I spray more to flametube when I use afterburner, example 20 to flametube and rest 30 to afterburner?
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