Lockwood-H pulsejet with variations will it work?

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Joris
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Lockwood-H pulsejet with variations will it work?

Post by Joris » Thu Jan 21, 2016 11:28 am

I'm planning on building a pulse jet in the near future, for the design i used the 1967 lockwood patent, using all the proportions in this patent i came up with the following sizes. Because i can't make a inwards tapering cone bend i instead decided to end the inward tapering cone before the bend and i also made the exhaust and inlet end at the same height. I would appreciate it if someone would take a look and guess whether or not they think it'll work, mostly whether the non inward tapering bend will work with the pipe in between the combustion chamber and the bend.

Also the diameter of the bend is the diameter from the middle of the tube to the middle of the opposite tube.

The proportions (all gotten from the lockwood patent, Combustion chamber has a 45º angle on both sides)
O means towards the exhaust
I means towards the inlet
L means length
M means average diameter
NozzleM=4,15"
CombustionM=11"
ExhaustM=3,825"
ExhaustO/ExhaustI=1,55
ExhaustL=28*ExhaustM
CombustionO/CombustionI=1,0625
CombustionL=CombustionM*1,45
NozzleO/NozzleI=1,083
NozzleL=NozzleM*3,85
CombustionI/NozzleO=2,46
ComustionO/ExhaustI=3,66

i do not own the rights to this picture i took it from the valveless pulsejets 1,5 pdf i got from this site, as said i got the dimensions from a patent in 1967 which i believe has expired. The patent has been included the file's called pulsejet proporties forgot to change the title. I've included the excel file i made for the size calculations if required i can easily change all the proportions, it also includes the circles and degrees i'm planning on using to make the cones.


Update 1:
Whilst looking around to see if my answer was in some other section i found a patent in the pulsejet designs section, this design comes pretty close to my design apart from my tailpipe being quite allot longer about 34 inches and the diameter of my combustion chamber was quite allot bigger a difference of 4,28 inches on the tailpipe side. I noticed that the angles on both sides of the combustion chamber towards the tailpipe and towards the nozzle aren't 45º where as my design is based on a 45º angle.

To fix the length of the tailpipe i could i it isn't functioning take out the piece between the combustion chamber and the bend which is part of the tailpipe. I've included the other design from the forum.


Update 2:
After tweeking my design to match up with the design i posted in my previous reply i'm quite sure i've got one working now with a few slight differences, for one i'm still using a 45º angle the combustion chamber and both the exhaust and the intake. and as i've already got a 180º bend i've tweeked so the total exhaust length comes up to the 72,7 inches long. Also i used my own program to calculate it all so both ends come up to the same point (intake and exhaust). The almost unreadable number specifying the intake end of the combustion chamber was when i google image searched it 6,5 inches according to one Swedish forum if someone knows whether or not that's true please do tell me.


(I thought it might get noticed as a separate thread i frist posted them in the i am new and i need help section)
Attachments
Lockwood designs.JPG
update 1
Pulse jet dimensions.jpg
also first upload
Sizes pdf.pdf
first upload
(54.49 KiB) Downloaded 74 times
Last edited by Joris on Thu Jan 21, 2016 11:46 am, edited 1 time in total.

Joris
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Re: Lockwood-H pulsejet with variations will it work?

Post by Joris » Thu Jan 21, 2016 11:44 am

tl;dr: i've got two designs the second of which varies very slightly from the design from the pulsejet plans section.

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Re: Lockwood-H pulsejet with variations will it work?

Post by Joris » Sat Jan 30, 2016 8:45 pm

I built it, tomorrow is test day i'll be posting the video here. It's not perfectly round and the welds aren't great but it should be good enough to get working i think.
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Jet engine.png

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Re: Lockwood-H pulsejet with variations will it work?

Post by Mike Everman » Sun Jan 31, 2016 4:24 pm

Looks great. Don't forget your intake flare.
It's been quiet about your questions about whether your altered design will work. No one really can say. This size engine is pretty forgiving of dimensions if you get fuel feed right. Things like the CC taper can be eliminated for sure; sorry, I should have mentioned that, but again, we hesitate to say for sure something will or won't work because our rules of thumb and simplistic acoustic models just don't cut it.
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Re: Lockwood-H pulsejet with variations will it work?

Post by Joris » Sun Jan 31, 2016 8:06 pm

I got it functioning for several seconds before it blew itself out i actually thought it was the amount of fuel i pumped in it but if that's the case i'm gonna make myself a intake flare tomorrow, my fuel system isn't that pretty so i'll weld on an intake cone to help. What angle/length do you recommend using for a jet with this design?

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Re: Lockwood-H pulsejet with variations will it work?

Post by Joris » Mon Feb 01, 2016 8:43 am

Will do, almost didn't spot your response as you changed my message, i'll try and test it again this afternoon

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Re: Lockwood-H pulsejet with variations will it work?

Post by metiz » Mon Feb 01, 2016 1:02 pm

Shit sorry, pressed the wrong button. Fixed it. For achival purposes:

don't weld a cone, just flare the intake
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Re: Lockwood-H pulsejet with variations will it work?

Post by Joris » Mon Feb 01, 2016 3:18 pm

Do you think this'll work? One of my welds tore a little so i didn't want to push it further, it's easy to fix now but it might not be if i bend it further.
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Re: Lockwood-H pulsejet with variations will it work?

Post by Mike Everman » Mon Feb 01, 2016 6:11 pm

Yes, that should be just fine.
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Re: Lockwood-H pulsejet with variations will it work?

Post by Joris » Mon Feb 01, 2016 7:23 pm

Awesome! I'll test it as soon as possible the wind was terrible today and i like my hair the way it is.

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Re: Lockwood-H pulsejet with variations will it work?

Post by Joris » Tue Feb 02, 2016 5:04 pm

I've been trying to start it but it hasn't been succesfull, i got it starting several times for a few seconds without air again, but it wouldn't sustain. As the file was too large to upload: https://youtu.be/9HH0bCj-x4w

I think the issues might be partly due to the positioning and the way i did the fuel injection. I used a single 22mm diameter tube with 20 3mm holes drilled through it, when i looked inside of the engine i saw that not the entire combustion chamber was actually being used, i did not tilt the gas supply whilst testing when i wanted to i was already out of gas.

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Re: Lockwood-H pulsejet with variations will it work?

Post by Joris » Tue Feb 02, 2016 6:14 pm

Update, Got it working on full power with more gas, it still didn't sustain though. The force was great enough to blow back my leafblower.

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Re: Lockwood-H pulsejet with variations will it work?

Post by Joris » Tue Feb 02, 2016 9:48 pm

Update again, I got it running for a bit 10-15 sec but it stopped i think this was due to being out of gas not completely sure.
I think i'm gonna have to get even more gas tomorrow, probably fill up my big tank.

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Re: Lockwood-H pulsejet with variations will it work?

Post by Joris » Wed Feb 03, 2016 1:54 pm

By doubling the gas input and an extra leafblower (replaced mine with one that varied in strength) I GOT IT STARTED. It works perfect now, i couldn't run it for too long because of my neighbours (did it in my backyard).

Vid: https://www.youtube.com/watch?v=2gkdweAOs00

Thanks to you Mike and Metiz, Thanks A TON! :D

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Re: Lockwood-H pulsejet with variations will it work?

Post by metiz » Wed Feb 03, 2016 4:20 pm

Good job!
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