mitch
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Joined: August 2014
Posts: 285
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Post by mitch on Dec 21, 2014 0:34:33 GMT -5
Question for anyone reading this thread, where does one find couplings for Hago nozzles? I found that mine are threaded to a compression fitting thread, and I have been using them with 3/8 compression fittings and copper tube. This works, but not very well.
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Post by finiteparts on Dec 21, 2014 14:34:23 GMT -5
Mitch,
I would measure the threads and buy a tap. I did that for my bypass style nozzle because the brass adapter was $70! The tap was around $8...Their (Danfoss Hugo) website says that it is a 9/16" x 24 UNEF thread, but I would check with a thread gauge. Plus, if you get a tap, you can make it out of something other than brass.
I hope that helps,
Chris
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mitch
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Post by mitch on Dec 21, 2014 17:49:23 GMT -5
finiteparts, yeah that helps! In the mean time, I think I found a solution. I found a 3/8 female compression x 3/8 female compression "swivel adapter" that should work. It uses rubber gasket type things in the base of the adapter that are removable. I fear they will melt, so I got some 1/4" lock washers that fit in almost perfectly, that should work in place of the rubber gaskets.
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mitch
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Posts: 285
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Post by mitch on Dec 22, 2014 14:10:15 GMT -5
Starting to drill the holes in the flame tube Evap tube for comparison/ to show where the primary holes will line up in relation to the branches
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mitch
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Post by mitch on Jan 5, 2015 19:46:05 GMT -5
The new combustion chamber is almost completed, just a few welds away from finishing! Had to include a pic of the exhaust flange welded to the combustion chamber... welds aren't bad! Size comparison of the chamber next to a 4 cylinder fuel rail, with some pumpkins growing in the background
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mitch
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Joined: August 2014
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Post by mitch on Jan 10, 2015 19:03:37 GMT -5
I tried to run the engine today, which was difficult since it was about 5 Fahrenheit outside today. I wasn't able to get the engine to self sustain, as it was too cold for my propane tank to put out decent pressure and the battery for my liquid fuel pump was dead. I was happy with how easily it started up, the old chamber used to be touchy to try to start, but the new one starts pretty easily. Hopefully I will be able to do a run on kerosene tomorrow, letting the fuel pump battery charge tonight and I am heating up the propane in the house.
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Post by racket on Jan 10, 2015 20:43:11 GMT -5
Hi Mitch
It might pay to heat the whole engine and oil tank prior to starting , throw a cover over the engine and use an electric blower heater to blow hot air under the cover , with a warm engine and oil it'll spoolup much easier .
Cheers John
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mitch
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Post by mitch on Jan 11, 2015 1:33:42 GMT -5
racket, I have the engine sitting in a room in my shed that is heated with a wood stove, and is around 55 degrees. I used a blow torch today to gently heat the oil tank and the hard oil lines to help heat up the oil, which seemed to work decently. That is a good suggestion though! I was able to get a decent charge on the fuel pump battery by heating it up near the blower on the wood stove, so that problem should be fixed. I'll get a video of the engine running and have it up hopefully by tomorrow night.
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Post by racket on Jan 11, 2015 2:56:37 GMT -5
Hi Mitch
All the best with the test run :-)
Cheers John
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mitch
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Post by mitch on Jan 11, 2015 15:48:31 GMT -5
The test runs were interesting...
I'll have videos up later, I basically had 2 cases of runaway turbojet!!! First one, an intake elbow blew off at over 20lbs of "boost". The second run, there was a massive pooling of kerosene in the combustion chamber, which led to a scary situation, no idea how much "boost" it made, or egt, but I know that EGT was skyrocketing because of the fact that the burning fuel completely bypassed the flame tube. The turbojet almost jumped off of the stand it was on because of the thrust it was making. I had cut fuel and spark/ignition when I noticed the flames coming out of the turbine housing and the smoke coming from the chamber, but it kept on spooling!!! As you might be able to see in the video, I hit the deck at this point... I ran and hid behind a car parked near me until it had burned out all of the excess fuel built up. My theory is two things: first, I did not let the evap system heat up enough, resulting in pooling of fuel. Second, I am using a nozzle that flows far too much, which is overwhelming the already cold evap system, resulting in pooling of fuel again. To combat this, I will switch my 15 gph nozzle for a 4 gph nozzle, and allow more time for the combustion chamber to heat up to allow for proper vaporization of fuel.
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Post by racket on Jan 11, 2015 16:31:42 GMT -5
Hi Mitch
LOL.............a "character building experience" ;-)
We should always have a drain cock in the lowest part of the combustor which can be opened prior to spoolup to drain any accumulated fuel , it need not be very big , a 1/4" bore is plenty .
Yep , a 4 GPH nozzle should be adequate at this early stage of development .
Cheers John
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Post by finiteparts on Jan 11, 2015 16:46:46 GMT -5
Hi Mitch,
Another thing to consider is that those pressure atomized nozzle are designed to "seal" on the flat face just past the threads. A common reason for leakage on home oil burners is a nick or a piece of dirt stuck between the two sealing faces, which does not allow the nozzle and housing facesto fully contact and seal. The threads are not gonna hold back the fuel pressure unless they are tapered threads that jam together forming a "seal" (like NPT threads). If you are using a swivel compression fitting you might have two leakage areas. One, where the fuel nozzle sealing surface might not be tight and the second could be the swivel part of the connection. The rubber ring was for sealing and a split washer will not really form a seal. You might want to test the nozzle outside of the combustor to see if it is leaking and thus causing continuous fuel spillage in the combustor.
Take comfort in that same thing happened to Whittle and team in an early engine test.
Good luck!
~ Chris
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mitch
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Post by mitch on Jan 11, 2015 17:09:59 GMT -5
racket and finiteparts, those are both really good suggestions. After examining my video, I found that I do have a large amount of kerosene leaking from the rear of the chamber before runaway occurred, so the leaking fitting might be the problem. Here is one of the videos: www.youtube.com/watch?v=S7Y25Om3Jks&feature=youtu.beWhile it was scary... I gotta say that power that thing made was incredible! never heard such a loud whistle in my life!
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Post by racket on Jan 11, 2015 18:36:11 GMT -5
Hi Mitch
An interesting video :-)
Without a jet nozzle you won't need as much fuel as when one is installed ...............your turbo probably flows around 1 lb/sec of air so ~1 lb/min of fuel when a jet nozzle is installed and running at higher temps at max rpm , without the jet nozzle maybe only 0.75 lbs/min of fuel or 45 lbs/hr or ~6.5 GPH , now a lot of fuel nozzles are calibrated at 100psi pressure drop across them , but at say 40 psi P2 you'll only have ~60 psi of drop so the nozzle will only be flowing at ~75% of its rated flow if the delivery pressure is 100 psi , if your delivery pressure is less than 100psi then there'll be an even bigger variation from the stamped flow rate on the nozzle.
Have you got any info on your fuel pressures ?
Cheers John
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mitch
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Post by mitch on Jan 11, 2015 22:28:40 GMT -5
racket, I see what you are saying. In the run you just saw, the fuel pressure never got above 20 psi. I have a pump capable of 100 psi, which means I can safely run it at pressures much lower than 100 psi. In the video I uploaded a few months ago, with the engine at idle around 5-8 lbs of "boost", I had a steady fuel pressure of about 10-15 psi.
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