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Post by racket on Jan 10, 2022 2:00:12 GMT -5
Hi Guys Thought it was time to have a look at the A/B mounting , so had a play today She's kinda long at ~5 feet - 1500mm Cheers John
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praendy2203
Veteran Member
Joined: August 2020
Posts: 181
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Post by praendy2203 on Jan 10, 2022 11:59:23 GMT -5
Hi John,
thats a good heater for your current weather😉
Looks impressive👍 Waiting for the first roarrchchchch...
Andy
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Post by andym on Jan 11, 2022 11:11:12 GMT -5
Hi Guys Thought it was time to have a look at the A/B mounting , so had a play today She's kinda long at ~5 feet - 1500mm Cheers John Going to make some noise .... looking forward
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Post by smithy1 on Jan 12, 2022 15:27:34 GMT -5
Hi Guys Thought it was time to have a look at the A/B mounting , so had a play today She's kinda long at ~5 feet - 1500mm Cheers John Only 5ft..?? Ppppffftttt....You can do better than that mate..! Dump type A/B too, very nice. What fuel supply/pump setup are you thinking..?? Am running twin Bosch 044's on mine, no need for a lot of pressure, just volume. Smithy.
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Post by racket on Jan 12, 2022 15:41:22 GMT -5
Hi Smithy
Yep , I'll be running the same twin pumps , I'm starting off with a dozen 1.1mm dia injection holes for the fuel .
Currently trying to workout a suitable mounting method for the A/B , at present its a slide on fit over the engines exhaust stub , but thats creating problems because of axial expansion issues , so will turn up a V band flange so that I can secure the A/B to the stub , at the back end of the A/B I'll make a "flexible" mount to cope with the expansions.
The weather has been been too hot and humid for me to get much work done , I've been hiding inside by the aircon :-)
Cheers John
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Post by racket on Jan 14, 2022 21:49:22 GMT -5
Hi Guys Have done more work on the A/B with the A/B resting in a cradle at the rear with a spring loading The A/B seems to clear the trailer mounted thrust structure , so all looking good , just need to get the front end sorted. With the A/B removed I'll get the gas producer ready for a test run this week if all goes well :-) Cheers John
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Post by racket on Jan 22, 2022 17:57:29 GMT -5
Hi Guys Still waiting for the weather to improve so decided to add a "rough" 118mm jetnozzle onto the engine , I scaled up from the 108 mm one I used on the 12/118 engine, using the turb wheel exducer flow areas which are the limiting factor. Not much of a reduction between exducer diameter and nozzle, 127 to 118 mm ~9mm , the 12/118 was from 112 to 108mm , only 4 mm , I'm hopeful it'll be OK Cheers John
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Post by racket on Jan 26, 2022 0:07:56 GMT -5
Hi Guys Today I finally felt up to doing a test run with the 118mm jet nozzle and twin 044 pumps on the outside and injector mods inside . Results ...............bugger all difference to last run :-( Will do more autopsy viewing of the vids just to be certain , but I feel I'm gunna have to change things inside, the fuel just isn't burning at higher power settings , nothing wrong with the flametube as it works fine at lower powers with nice even temps exiting the wheel I was running 85 psi fuel pressure but still couldn't get up to higher P2s , with another 15 psi of P2 I'd be needing >120 psi of fuel pressure , not doable . Vids youtu.be/2v1Sa0RhfoMyoutu.be/0BhsnInvqhUCheers John
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praendy2203
Veteran Member
Joined: August 2020
Posts: 181
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Post by praendy2203 on Jan 26, 2022 2:26:11 GMT -5
Hi John,
I still think, there is a combustion problem.
The jump from 1,5 to 2 Bar P2 shows more than 100°C Egt. Then from 2 - 2,2 Bar P2 almost another 100°C Egt.
Than more fuel pressure you add, than more the flame gets pushed to the ngv side.
Dont know, how to solve this problem.
You spent already some time in the fuel system.
Maybe cover some holes in the front wall. This may prevent, pushing the flame to the aft section.
At least use the vaporizer system🤔
Andy
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Post by racket on Jan 26, 2022 2:59:55 GMT -5
Hi Andy
Yep , theres certainly a problem :-(
I removed the jetnozzle and there appears to be a "hot streak" witness mark along the top , ... strange .
The two thermocouples were pretty much in lockstep as power was increased , but when the power was reduced , one side was a lot hotter than the other ,......strange again .
Gotta have a look inside .
Most likely I'll redo the entire flametube to the design of the 12/118 engine , 1/2" OD X 0.025" wall thickness vapourisers with square springs inside discharging onto aircaps with the primary air flowing out of the sides of the caps.
The current flametube might never be made to work if the combustion is delayed in a very short length of combustor , it sends the loading too high in the remainder.
Hopefully alls OK inside , the rotor is still spinning smoothly and even though the temps were high , the "colour" inside the jetpipe wasn't that "bright" , just a dull red for the wheel which on a cloudy overcast day was easy to see.
Will post pics of any "abberations" ;-)
Cheers John
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Post by wannabebuilderuk on Jan 26, 2022 4:08:30 GMT -5
Don't beat yourself up about it John, it's still impressive how far you've come to be able to make something like this in such a short time to such high quality!
Ben
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Post by racket on Jan 26, 2022 4:47:32 GMT -5
Thanks Ben , she'll get there eventually , still early days :-)
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jetric
Veteran Member
Joined: December 2014
Posts: 141
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Post by jetric on Jan 26, 2022 12:47:29 GMT -5
Hi John, Are you trying to increase fuel flow or pressure with your twin fuel pumps. If you are trying to increase flow then you will need the pumps plumbed up in parallel such as your set up at the minute, If you are Tring to increase the pressure then you will have to plumb them up in series. With the pumps in series you should be able to reach 160psi easily, this is all to do with the internal pressure relief valve inside the pumps. If you do plumb the pumps in series I would recommend wiring them up in series as well as this will automatically make the pumps share the pressure load of the fuel but you will have to run the pumps at 24volt and also electrically insulate each pump from each other as the pump casings are connected to the negative terminal i.e. Plastic or rubber pipe between the pumps and insulate the pump body's from there mounts. With regards to your combustion problems it looks like a lack of oxygen in your primary zone preventing the fuel from burning until it reaches the secondary zone this is evedent from your high levels of soot deposits in the primary. The one thing that has been bugging me was when you where having soot deposits on the outside of your front plate of your flame tube, just food for thought do you think that the air exiting your defuser is creating a low pressure zone at the outside of the front face of the flame tube preventing air from entering through your primary zone holes thus creating the over rich retarded burning primary zone. Richard S. Hi Guys Today I finally felt up to doing a test run with the 118mm jet nozzle and twin 044 pumps on the outside and injector mods inside . Results ...............bugger all difference to last run :-( Will do more autopsy viewing of the vids just to be certain , but I feel I'm gunna have to change things inside, the fuel just isn't burning at higher power settings , nothing wrong with the flametube as it works fine at lower powers with nice even temps exiting the wheel I was running 85 psi fuel pressure but still couldn't get up to higher P2s , with another 15 psi of P2 I'd be needing >120 psi of fuel pressure , not doable . Vids youtu.be/2v1Sa0RhfoMyoutu.be/0BhsnInvqhUCheers John
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Post by racket on Jan 26, 2022 22:24:36 GMT -5
Hi Richard I've been trying to increase flow by adding the extra pump , the single 044 simply couldn't supply sufficient at the pressure required so I felt that adding the second pump would mean twice the potential flow at that 80+psi , but somehow this isn't happening . An insitu flow test with the single pump at 40psi delivery pressure , flowed 3,000ml/min - 5lbs/min through the injectors , which with my ~80 psi fuel pressure when the engine was running with 36 psi P2 during my 3/12/21 test would have meant maybe 3200 ml/m - 5.4 lbs/min of fuel going in. The soot problem seems more pronounced after yesterdays test with soot now depositing past the Secondary holes , 30% of total hole area is for Primary and 20% for Secondary , so plenty of air available I also found 4 injectors not doing their job , these small bore 21G injectors are just so fragile , I'm really not happy with what I've found , might be time to cut my loses and go to vapourisers with large injectors and modest fuel pressures that a single 044 pump can cope with Thankfully everything else in the engine is OK Cheers John
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Post by racket on Jan 27, 2022 16:55:56 GMT -5
Hi Guys I've been having a good look at the gauges video www.youtube.com/watch?v=0BhsnInvqhU after having a good long chat to Andy M where he noticed some interesting sequences . When the video is at 1.40 minutes not long after spoolup the P2 g/g is bouncing wildly at a couple/second . At 3.30 min after reducing power from max the P2 g/g is "steady" at the same P2 as post spoolup . Now Andy and I both feel this is probably because of the fuel hitting hot metal after the high power run and vapourising producing "steady" combustion . At 4.15 min this happens again , but with subsequent "cooling" the bouncing starts to reappear by 4.30 5.20 and 5.30 again . Thankfully this has eased my mind that it was a compressor issue , surge , rotating stall etc etc , and its probably just combustion . More viewing required :-) Cheers John
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