Lockwood Pulse Jet won't sustain

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saurav
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Lockwood Pulse Jet won't sustain

Post by saurav » Sun Apr 28, 2013 8:22 am

I have built the bruce simpson 55lb lockwood pulse jet of dimensions given in the pdf file below. Now the problem is very much explained by watching the video below.
1.We are using a 10lb propane tank with no pressure reducing part.
2. Fuel injector is an array of 4x1.8mm holes of 3 in a ray. fuel is injected radially
3. Fuel injector is placed just at the beginning of combustion chamber.

The farthest we could get was a very deep and loud rumble out of it with the air from blower on.

The propane tank was in upright position in the video.

When I tilt the propane tank, the rumble gets louder and intense.

During whole of this phase, the fuel valves were open completely

Please, suggest me something I need to get this engine working as quick as possible... :?: :?

John Hasler
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Re: Lockwood Pulse Jet won't sustain

Post by John Hasler » Sun Apr 28, 2013 5:39 pm

I see no pdf or video. In any case, you probably need to turn the propane tank upside down and feed the engine liquid propane. If you have one of the "new, improved" tanks with the built-in regulator you're out of luck.

Chook
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Re: Lockwood Pulse Jet won't sustain

Post by Chook » Sun Apr 28, 2013 11:47 pm

Hi mine was a bit hard to start, untill I understood what was needed to get it to fire consistantly.

viewtopic.php?f=3&t=6577

I'm using a radial injector with 12 x 1mm holes around it. It is positioned in the centre of the transition cone. The holes face 15 degrees to the rear.

When starting I turn the gas (vapour) on and make sure its lit and billowing out the exhaust in a nice red/orange flame. (this doesn't need much gas to happen) Then pass (Don't hold it there)the leaf blower past the intake to shock it and get it resonating/combusting. The gas can then be increased once it's warmed up for 10 seconds or so. If it's still to cool it will quit when more gas is added.
Mine runs at 262 Hz (fires at 262 times a second)

Hope this helps, Chook

saurav
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Re: Lockwood Pulse Jet won't sustain

Post by saurav » Mon Apr 29, 2013 3:54 am

Sorry for the late video upload, I didn't know the upload size was limited to 2mb only.... its uploaded now

also wanted to add, whenever blue colored flames are generated, the rumble gets deeper and louder....

Will be uploading the image of injector today only....

thanks for the replies.... :)
Attachments
Sequence 01.mp4
(1.69 MiB) Downloaded 192 times
Last edited by saurav on Mon Apr 29, 2013 5:12 am, edited 1 time in total.

saurav
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Re: Lockwood Pulse Jet won't sustain

Post by saurav » Mon Apr 29, 2013 5:10 am

here are the detailed views of the arrangement....
Attachments
injector labelled.jpg
details of the injector
injector flow.jpg
simulation of the fuel flow using water
location of fuel injector.jpg
approximate injector location
gas regulator.jpg
unreduced pressure gas regulator is basically used as a turn on and off
fuel line.jpg
fuel line arrangement
engine.JPG
overview of the engine

saurav
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Re: Lockwood Pulse Jet won't sustain

Post by saurav » Mon Apr 29, 2013 7:19 am

Chook wrote:
The holes face 15 degrees to the rear.
hmm, holes angled to rear, must try it out. Probably this is why I wasn't getting flames out of exhaust when air wasn't forced

but don't you think the very small thickness of pipe won't make any difference? what thickness of pipe were you using, can you post an image or point me to it somewhere on the forums? and also please tell me the exact location of injector nozzle, because I noticed during my testing that even 1cm movement made a difference......

Chook
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Re: Lockwood Pulse Jet won't sustain

Post by Chook » Mon Apr 29, 2013 3:23 pm

I made mine like the one ¾ down the page by Dang911.
viewtopic.php?f=3&t=2885&hilit=lockwood+startup
It is mounted to 10mm (instead of 6mm)hydraulic tube and then is centred in the pipe by 3 push bike wheel spokes that are just sprung in to fit it into the centre of the pipe. The injector sits right in the centre of the transition cone to the combustion chamber. You can see the spokes here, if you click the photo to enlarge it..
055 (1024x576).jpg
My motor is made out of 1.55 mm galvanized sheet so I added 7 rings of 5mm round rod, to the top pipe to stop it sucking flat when hot. It emits a nice blue flame out the intake and a nice orange out the exhaust.
093 (1024x576).jpg
Here is the starting flame. And my mate is just about to wave the leaf blower past the inlet. (It's the bottom tube on this leaf blower that blows, the big top one only sucks, when the baffles is changed.)
021 (1024x576).jpg
Hope this helps. Chook :D

saurav
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Re: Lockwood Pulse Jet won't sustain

Post by saurav » Mon Apr 29, 2013 3:50 pm

thanks for the images,

were really helpful :)

I will surely try out the suggested injector,

but for now can you find anything wrong with the arrangement and procedure in images above?

do I always need to invert the fuel tank to start it?

by the way, watching your engine running, gives me a rush anticipating how it will work :D

Chook
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Re: Lockwood Pulse Jet won't sustain

Post by Chook » Tue Apr 30, 2013 12:42 am

Hi Saurav. No I don't invert my gas bottle to start.

I have tried it with the bottle upside down, but it won't run for more than 10 or 15 seconds before flaming out. It took me a long time to work out what was going wrong (with the bottle inverted) and in frustration, left the bottle the correct way up and after much fuel adjusting /fiddling, away it went at a low idle till it warmed up. Then full power could be added.
It’s too much liquid LPG for the injector I'm using. A huge thank you, to “John Hasler”, for sorting me out here.

I don't know enough about these things to comment on your injector and the size of the holes. That’s the real reason I'm not running mine on liquid LPG, as I don't know what jetting the injector would need for liquid.

Can someone chime in with the correct sizes, to get Saurav going here, as his motor looks fantastic.
Can't wait to see her running. :D :D

The only comment I would make on your starting video is, mine will not start, when a constant air stream is held in the intake. It needs to be waved past the intake to create a shock, or resonance to get it fired up. I would be interested to hear if this is the case to all of them.

Please persevere, as you are sooo…. close to having a great time.
The sound these motors make, is to die for!!!! :shock:

The photos were taken as part of a documentry that was being filmed by the BBC and should be shown in England later this year.
040 (1024x576).jpg
Chook

saurav
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Re: Lockwood Pulse Jet won't sustain

Post by saurav » Tue Apr 30, 2013 1:47 am

thanks chook :D

surely looking forward to watch the BBC documentary :P

Is it very important for the nozzle to be in a radial center?

saurav
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Re: Lockwood Pulse Jet won't sustain

Post by saurav » Mon May 13, 2013 2:35 am

today I tested the engine again and noticed that after attaching an extension pip to the blower and ran it sticking somewhat inside the intake and immediately noticed a very loud and deep roar whose thump I could feel on my chest.

:shock:

saurav
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Re: Lockwood Pulse Jet won't sustain

Post by saurav » Tue May 14, 2013 1:05 am

Chook wrote:Hi Saurav. No I don't invert my gas bottle to start.

Chook
hey "Chook", I tried with your fuel injector design. Again, couldn't get it past the extremely loud rumbling sound. Although I noticed that when I invert the tank, the sound it generates seems a lot like the ones in videos when theirs is about to run.

I am beginning to doubt the pressure that my little propane tank can generate is enough to start this hungry fellow.

What was the weight of the tank that you ran your pulse jet on, "Chook"?

Please reply me soon I am very impatient now to start it as I seem to be so close to start it....

Chook
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Re: Lockwood Pulse Jet won't sustain

Post by Chook » Wed May 15, 2013 12:35 pm

Hi, You must be very frustrated when you are this close!!!! :?

My LPG bottle holds 8.5 Kg of gas, but it will never empty it when running as the bottle freezes up and leaves 100mm of gas in the bottom, after each run.

I decant/fill, the bottles, so I always have a full one for every start.
Mine just won't start, with a level below 3/4 of a bottle.

After warming up, when mine is running the valve on the bottle is (always) fully on and so is the 10mm "throttle", ball valve.

Hope you have a break through shortly.

Good luck, Chook

saurav
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Re: Lockwood Pulse Jet won't sustain

Post by saurav » Wed May 15, 2013 3:24 pm

Yesterday I tried the commercial 30lb propane tank and couldn't get any improvement.

something else is missing,

should I try the swizzle stick design as shown by someone in the picture, his engine is running. Given in the forum below

viewtopic.php?f=3&t=5927

its about 3/4th the page down

here is the video of the radial fuel injector as directed by 'chook'

Can you(chook) please provide me with the images of the injector of yours and its exact location from the intake flare. They will be extremely helpful. :)

one more thing, have you ever observed that your engine doesn't run when the injector is not at the exact radial center?
actually I don't have a special arrangement to keep it at the radial center, it is just a kept in an approximate center, I am not using any bicycle spokes to keep it in the center.
Attachments
Sequence 01.mp4
(1.53 MiB) Downloaded 187 times

Chook
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Re: Lockwood Pulse Jet won't sustain

Post by Chook » Thu May 16, 2013 2:49 am

Hi I'm not at home just at the moment.

Looking at the video it seems to be over fuelled (too much gas) to start. :?:

I let the lit orange gas, plume out the exhaust for a couple of seconds and then shock the intake with the leaf blower.

You are so very close, I can't believe it hasn't continued to run.

When I'm home, I'll measure the nozzle location exactly for you.

My gas line does 3 circuits around the pipe past the combustion chamber to preheat the gas but I don't know how important this is.
P1010768 (1024x768).jpg
It would not run with the bottle inverted for more than 10 seconds or so, so ignore the bottle this way up in the photo.
I reckon if your injector is close to the centre it would be ok. I don't think it would be that critical.????
Can some one help us here please.
Chook

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